Patent Grant
9080146
This disclosure relates to substrates and to methods for producing substrates that have utility as matrices or surfaces for producing biological materials that can be implanted in mammals.
Culturing of cells, especially endothelial cells, with the goal of growing artificial organs is an important development in implantology. One particular advantage of this technology is that implants prepared in this manner are expected to exhibit complete compatibility with the body. Because cell collections cultured ex vivo initially do not have either the shape or the mechanical stability desired for the later implants such as organs, arteries, and the like, such implants can be initially preformed on a form-building or “forming” substrate on which cells are cultured. These form-building substrates can serve as primary supporting structures or supporting substrates on which cells are cultured and developed.
Examples of form-building substrates that have been studied as possible primary supporting structures for such implant formation include polylactides, polyethylene glycols, polyurethanes, polytetrafluoroethylene (PTFE or Teflon®), and inorganic substrates, as well as more common materials such as polyurethanes, polyethylenes, and polypropylenes. Other potential materials included hydrolyzed polyacrylonitrile, hydrophilic polyethers, diacrylates, an expandable shell of epsilon-PTFE, and various hydrogels. This group of potentially applicable materials can also be supplemented by polyvinylpyrrolidone (PVP), polyvinyl alcohols (PVA), polyethylene oxide (PEO), and polyhydroxyethyl methacrylate p(HEMA). Examples of form-building substrates which are supporting structures for cell cultures have been disclosed, for example, in WO 98/56312, WO 96/00103, EP-A-0 810 845, U.S. Pat. Nos. 4,883,699, 4,911,691, 4,480,642, 4,798,876, 4,424,395, and EP-A-0 804 909, the entire disclosures of which are incorporated herein by reference.
Because the inherent properties of these materials are unique, each of these potential substrates exhibits characteristics that make them more or less useful for certain applications in the culture of artificial implants. Similarly, these materials also have certain undesirable properties, such as limited blood or tissue compatibility, difficulty in preparing or processing the material, difficulty in fabricating the supporting substrate itself excessive porosity that leads to strong cell adhesion and results in damage when separating the cultured cell material from the supporting substrate. Other materials may require the addition of plasticizers to achieve the desired properties, which can reduce compatibility with the blood and various cells and tissues.
Accordingly, there is a need to develop substrate materials that can serve as form-building or “forming” substrates, on which cells can be cultured. There is also a need to understand and develop substrate materials as matrices for producing biological materials that can be implanted in a mammal. There is also a need to be able to control the degree or extent of cellular adhesion at or on a substrate, for example within, around, and at the interfacial boundary contacting an implant.
The present disclosure relates to substrates containing a polyphosphazene with a form-building or forming surface, which are utilized as matrices for producing biological materials that can be implanted in a mammal. This disclosure also describes a process for producing such substrates, substrates containing polyphosphazene with micro-structured surfaces, and methods for regulating or “tuning” cellular adhesion at or on a substrate.
A number of difficulties can arise in the culturing of cells for implants from reaction with traditional supporting substrate materials or with their degradation products. For example, inflammatory reactions can occur in recipients due to the dissolving or absorption of some of the know substances, or because of reaction with decomposition products of some of the known substances (see: van der Gieben, Circulation, Volume 94, No. 7, 1996, which is incorporated herein by reference in its entirety). Furthermore, cracks and fractures can occur in the freshly cultured implant when the cultured implant is removed from the supporting substrate, if cultured cells bind too tightly to the supporting substrate due to its basic surface pore structure, or a pore structure that arises from dissolution of the supporting substrate. Such cracks are particularly problematic upon removal of cultured blood vessel implants from the supporting substrate, and constitute an important aspect in the production of vascular implants. Cracks, for instance, can be anchoring points for cellular and biomacromolecular attachment or serve as guiding motifs, giving rise to or triggering increased development of thrombi in recipients or patients, and for other deposits proteins, macrophages, and the like) that can become a risk for the recipients or patients after implantation.
Behavior with respect to bacteria and proteins that are deposited on the surfaces of the supporting substrate is also a factor affecting the successful culturing of implant cells, because bacteria and protein deposits can lead to significant inflammation in patients and to other problems with the growth and culture of the cells. In one aspect, for example, when an artificial substrate surface comes into contact with blood or any other biological fluids, a complex immune response is set into motion. For example, blood, urine, saliva, spinal fluids, and synovial fluids contain a wide variety of soluble proteins and other macromolecules of biological origin, which adsorb onto the introduced material to form a complex adsorbate layer. The composition and structure of this adsorbate layer largely can be determined by the varying affinities of the proteins and macromolecules towards the substrate. The subsequent cellular response is modulated through this adsorbate layer and may trigger adverse events such as the activation of the blood coagulation cascade. Associated complications may include acute or subacute thrombus formation, the initiation of inflammatory processes aided by bacterial infiltration and growth, accompanying biofilm formation, implant obstruction or occlusion through mineral encrustation, fatty deposit or calcified plaque formation, implant encapsulation or rejection, formation of myxoid tissue, scar formation, and necrosis.
Accordingly, in one aspect, this disclosure provides for a method of regulating cellular adhesion at or on a substrate, the method comprising:
In another aspect, regulating cellular adhesion at a substrate can be carried out by adjustments in the polyphosphazene micro-structure on the substrate by the selection of the substrate material itself in view of the particular polyphosphazene matrix to be fabricated on that substrate. By way of example, regulating cellular adhesion at a substrate can include such substrate material design selections as follows:
It is to be understood that tailoring the cellular adhesive behavior at a substrate or cellular response of any type on the basis of the substrate-polyphosphazene combination can be accomplished at selected domains or regions of a particular substrate, using techniques such as masking methods that are well understood by one or ordinary skill. It is also to be understood that the cellular adhesive behavior of selected domains or regions of a particular substrate can tailored by, for example, contacting selected portions of a substrate with at least one adhesion promoter to provide a treated substrate, followed by contacting the larger substrate containing treated and untreated portions with at least one polyphosphazene.
In a further aspect, regulating cellular adhesion at a substrate can be carried out by adjustments in the polyphosphazene micro-structure itself on the substrate. For example, increasing the polyphosphazene micro-structure on the substrate, and hence decreasing cellular attraction, can be effected by:
These and other aspects and embodiments are provided in more detail in the Detailed Description section of this disclosure.
The present disclosure is drawn to a system for producing implants from biological materials that allows for highly selective growth of the desired cells and to assuring essentially damage-free separation of implants made of the desired cells from the supporting substrate.
In one aspect, the system for producing implants from biological materials includes regulating the extent or degree of cellular adhesion or repulsion at a substrate that is being used to culture cells for the implant. In one aspect, for example, this disclosure provides method of regulating cellular adhesion at a substrate or to a substrate, the method comprising:
The disclosed method of regulating cellular adhesion at a substrate can be carried out by adjustments in the degree of cellular adhesion at the polyphosphazene micro-structured substrate, as compared to a known degree of cellular adhesion on a substrate prepared using a known polyphosphazene concentration in the polyphosphazene solution. For example, increasing the polyphosphazene micro-structure on the substrate as outlined above can be carried out in a variety of ways, including:
Further, the particular polyphosphazene can be used in combination with a particular biological material or biomacromolecules to tailor the micro-structure on the substrate and the cellular material produced therefrom. In this aspect, for example, a particular polyphosphazene can be used as a micro-structured masking area with known cellular modulations and modifying the substrate underneath by contacting the substrate with other solutions, such as solutions containing biomacromolecules known to have a specific affinity to the substrate material only. Alternately, this process can be carried out in a reverse fashion, that is, by using a particular polyphosphazene as a micro-structured specialized substrate and by contacting the material with solutions containing biomacromolecules with a specific affinity only for the polyphosphazene matrix.
In one aspect, the concentration of the polyphosphazene solution used to contact the substrate, whether treated or not, can be as low a concentration as desired, and can be up to about 200 mg per mL of solution if desired. Exemplary solvents for this process include various ketones, such as methyl ethyl ketone or acetone, esters such as ethyl acetate or butyl acetate, ethers such as THF, and also combinations thereof, including combinations with nonsolvents such as toluene, xylenes, and the like. In a further aspect, the concentration of the polyphosphazene solution used to contact the substrate, whether treated or not, can be up to about 150 mg per mL, up to about 125 mg per mL, up to about 100 mg per mL, up to about 75 mg per mL, up to about 50 mg per mL, up to about 35 mg per mL, to about 25 mg per mL, up to about 20 mg per mL, or up to about 15 mg per mL, up to about 10 mg per mL, up to about 5 mg per mL, up to about 2 mg per mL, up to about 1 mg per mL, or up to about 0.5 mg per mL, including any ranges or sub-ranges between these numbers. In a further aspect, solutions having a concentration derived from the inverse of the intrinsic viscosity of the polyphosphazene solutions, typically from about 0.5 to about 2.5 mg/mL, can be used.
Still a further aspect of this disclosure is a polyphosphazene micro-structured substrate having a polyphosphazene film thickness which can be up to about 1000 nm. Generally, as the polyphosphazene solution concentration is adjusted, the thickness of the resulting micro-structured surface is also adjusted, with higher concentrations providing thicker films. For example, the polyphosphazene micro-structured substrate prepared according to this disclosure can have a polyphosphazene film thickness up to about 1000 nm, up to about 750 mm, up to about 500 mm, up to about 400 mm, up to about 300 nm, up to about 200 nm, up to about 175 nm up to about 150 mm, up to about 125 nm, up to about 100 nm, up to about 75 nm, up to about 65 mm, up to about 60 nm, up to about 50 nm, up to about 40 nm, up to about 30 nm, up to about 20 nm, up to about 10 nm, up to about 5 nm, up to about 2 nm, or up to about 1 nm, including any ranges or sub-ranges between these numbers. In a further aspect, the polyphosphazene micro-structured substrate prepared according to this disclosure can have a lower limit polyphosphazene film thickness from about 1 nm, about 2 mm, about 3 n, about 4 n, or about 5 nm, up to any of the upper values disclosed. In one aspect, for the high molecular weight polyphosphazenes such as used in the Examples, polyphosphazene micro-structured substrates prepared according to this disclosure also can have a polyphosphazene film thickness from about 1 nm to about 300 nm.
When the polyphosphazene micro-structured substrate are prepared according to this disclosure, the spacing density of the void structure within the polyphosphazene micro-structured substrate can be from about 10,000 voids per 100 μm2 to 0 voids per 100 μm2, and any number between. In this aspect, for example, the spacing density of the void structure within the polyphosphazene micro-structured substrate prepared according to this disclosure can be from about 5,000-3,000 voids per 100 μm2, from about 4,000-3,000 voids per 100 μm2, from about 2,500-1,000 voids per 100 μm2, from about 2, 200-900 voids per 100 μm2, from about 1,000-600 voids per 100 μm2, from about 700-200 voids per 100 μm2, from about 500-200 voids per 100 μm2, from about 400-100 voids per 100 μm2, or from about 200-150 voids per 100 μm2, including any ranges or sub-ranges between these numbers. Moreover, any of these numbers can be combined as a range of voids per 100 μm2, for example, this disclosure is intended to include void structure spacing densities within the polyphosphazene micro-structured substrate of from about 5,000-3,000 voids per 100 μm2, to about 200-150 voids per 100 μm2, and ranges in between.
In a further aspect, when the polyphosphazene micro-structured substrate are prepared according to this disclosure, the polyphosphazene surface coverage of the polyphosphazene micro-structured substrate can be from near 0% to 100%, as surface coverage can be controlled along this continuum by the techniques disclosed herein. Particularly useful ranges include from about 25% to 100% and from 50% to 100% polyphosphazene surface coverage. In still another aspect, the polyphosphazene surface coverage of the polyphosphazene micro-structured substrate prepared according to this disclosure can be from about 50% to 100%, from about 75% to about 90%, from about 85% to about 95%, from about 90% to about 98%, from about 92% to about 97%, or from about 97% to about 97.5%, including any ranges or sub-ranges between these numbers.
In a further aspect of this disclosure, increasing the polyphosphazene micro-structure on the substrate and hence decreasing cellular adhesion and increasing cellular repulsion, can be effected by: a) increasing the polyphosphazene concentration in the polyphosphazene coating solution; b) increasing the polyphosphazene film thickness; c) decreasing the lateral spacing density of the void structure within the polyphosphazene micro-structured substrate per unit surface area; d) decreasing the average polyphosphazene-free pore size; e) increasing the substrate surface area covered by the polyphosphazene; or f) any combination thereof. Similarly, in this aspect, decreasing the polyphosphazene micro-structure on the substrate and hence increasing cellular adhesion and decreasing cellular repulsion, can be effected by: a) decreasing the polyphosphazene concentration in the polyphosphazene coating solution; b) decreasing the polyphosphazene film thickness; c) increasing the lateral spacing density of the void structure within the polyphosphazene micro-structured substrate per unit surface area; d) increasing the average polyphosphazene-free pore size; e) decreasing the substrate surface area covered by the polyphosphazene; or f) any combination thereof.
Polyphosphazenes
In one aspect, this disclosure provides the use of a substrate with a “forming” or form-building surface, that contains at least in part a polyphosphazene as a matrix for producing biological material that can be implanted in a mammal. In one aspect, for example, this disclosure provides the use of a substrate with a form-building surface, that contains at least in part a polyphosphazene having the following formula:
wherein
n is 2 to ∞; and
R1 to R6 are each selected independently from alkyl, aminoalkyl, haloalkyl, thioalkyl, thioaryl, alkoxy, haloalkoxy, aryloxy, haloaryloxy, alkylthiolate, arylthiolate, alkylsulfonyl, alkylamino, dialkylamino, heterocycloalkyl comprising one or more heteroatoms selected from nitrogen, oxygen, sulfur, phosphorus, or a combination thereof, or heteroaryl comprising one or more heteroatoms selected from nitrogen, oxygen, sulfur, phosphorus, or a combination thereof.
By indicating that n can be as large as so in formula A, it is intended to specify values of n that encompass polyphosphazene polymers that can have an average molecular weight of up to about 75 million Daltons. For example, in one aspect, n can vary from about 40 to about 100,000. In another aspect, by indicating that n can be as large as ∞ in formula I, it is intended to specify values of n can be from about 4,000 to about 50,000, from about 7,000 to about 40,000, or from about 13,000 to about 30,000. In a further aspect, the degree of polymerization (n) of the biocompatible polymer according to Formula (I) is typically in a range of about 20 to about 200,000, and generally from about 40 to about 100,000.
In another aspect of this disclosure, the polyphosphazene used to prepare the micro-structured surfaces can have a molecular weight based on the above formula, which can be a molecular weight of at least about 70,000 g/mol, a molecular weight of at least about 1,000,000 g/mol, or a molecular weight from at least about 3×106 g/mol to about 20×106 g/mol. In another aspect, the polyphosphazenes can have a molecular weight of at least about 10,000,000 g/mol.
In a further aspect of the polyphosphazene formula (I) and the definitions of R1 to R6, the pendant side groups or moieties (also termed “residues”) R1 to R6 are each independently variable and therefore can be the same or different. Further, R1 to R6 can be substituted or unsubstituted. The alkyl groups or moieties within the alkoxy, alkylsulfonyl, dialkylamino, and other alkyl-containing groups can be, for example, straight or branched chain alkyl groups having from 1 to 20 carbon atoms, typically from 1 to 12 carbon atoms, it being possible for the alkyl groups to be further substituted, for example, by at least one halogen atom, such as a fluorine atom or other functional group such as those noted for the R1 to R6 groups above. For example, by specifying alkyl groups such as propyl or butyl, it is intended to encompass any isomer of the particular alkyl group.
The alkyl groups in the alkoxy, alkylsulfonyl, dialkylamino, and any other alkyl-containing groups are, for example, straight-chain or branched-chain alkyl groups with 1 to 20 carbon atoms, wherein the alkyl groups can be, for example, substituted by at least one halogen atom, such as a fluorine atom. The 1 to 20 carbon atom, straight-chain or branched-chain description is also applicable to alkadiyl-type moieties such as aminoalkyl (amino-substituted alkyl groups) that can constitute R1 to R6.
In one aspect, examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, and butoxy groups, and the like, any of which can be substituted. For example, any alkoxy group can be substituted by one or more halogen atoms, such as fluorine atoms. One example of a suitable alkoxy group is the 2,2,2-trifluoroethoxy moiety. Thus, suitable alkoxy groups are OR groups in which R is any alkyl as defined herein. Thus, one one aspect, one or more of the alkoxy groups can contain at least one fluorine atom. Further, the alkoxy group can contain at least two fluorine atoms or the alkoxy group can contain three fluorine atoms. Certain alkoxy groups, such as iso-propyl and t-butyl, can contain six fluorine atoms. Alkoxy groups of the polymer can also be employed in combinations with other groups, including other variously substituted alkoxy groups. For example, combinations of alkoxy groups can be used, wherein one or more fluorine atoms are present on the polyphosphazene in combination with other groups or other substituent atoms.
Examples of alkylsulfonyl substituents include, but are not limited to, methylsulfonyl, ethylsulfonyl, propylsulfonyl, and butylsulfonyl groups.
Examples of dialkylamino substituents include, but are not limited to, dimethylamino, diethylamino, dipropylamino, and dibutylamino groups. Again, by specifying alkyl groups such as propyl or butyl, it is intended to encompass any isomer of the particular alkyl group.
An aryl group, for example as occurring in the aryloxy group can be, for example, a compound with one or more aromatic ring systems, in which the aryl group can be unsubstituted or substituted with one or more alkyl groups, one or more halogens, one or more alkoxy groups, one or more amino groups, or any combination thereof. Examples of aryl groups are phenyl, naphthyl, and substituted analogs thereof. In one aspect, for example, aryl groups in this disclosure can be substituted or unsubstituted and can have from 6 to about 20 carbon atoms. Accordingly, examples of aryloxy groups include, but are not limited to, phenoxy and naphthoxy groups, and substituted analogs or derivatives thereof including, for example, substituted phenoxy and naphthoxy groups.
The heterocycloalkyl group can be, for example, a ring system which contains from 3 to 10 atoms, or from 3 to 7 atoms, at least one ring atom being a nitrogen, oxygen, sulfur, phosphorus, or any combination of these heteroatoms. The hetereocycloalkyl group can be substituted, for example, by one or more alkyl, alkoxy, halide, or other substituent. Examples of heterocycloalkyl groups include, but are not limited to, imidazoline, imidazolidine, piperidinyl, piperazinyl, pyrrolidinyl, and morpholinyl groups, and substituted analogs thereof.
The heteroaryl group can be, for example, a compound having one or more aromatic ring systems, at least one ring atom being a nitrogen, an oxygen, a sulfur, a phosphorus, or any combination of these heteroatoms. The heteroaryl group can be substituted for example by one or more alkyl, alkoxy, halide, or other substituent. Examples of heteroaryl groups include, but are not limited to, imidazolyl, thiophene, furane, oxazolyl, pyrrolyl, pyridinyl, pyridinolyl, isoquinolinyl, and quinolinyl groups, and derivatives thereof, such as substituted groups.
In one aspect, this disclosure provides the use of a substrate with a “forming” or form-building surface, that contains at least in part the polyphosphazene, poly[bis(2,2,2-trifluoroethoxy)phosphazene] (also referred to further herein as poly[bis(trifluoroethoxy)-phosphazene]), or a derivative or analog thereof, as a matrix for producing biological material that can be implanted in a mammal. The polymer poly[bis(2,2,2-trifluoroethoxy)phosphazene] or derivatives thereof as disclosed herein, have chemical and biological qualities that distinguish this polymer from other know polymers in general, and from other know polyphosphazenes in particular. In a further aspect, the polyphosphazene can be derivatives of poly[bis(2,2,2-trifluoroethoxy) phosphazene], such as other alkoxide, halogenated alkoxide, or fluorinated alkoxide substituted analogs thereof.
In one aspect, the poly[bis(trifluoroethoxy)phosphazene] polymer can be made up of repeating monomers represented by formula (I), wherein R1 to R6 are all trifluoroethoxy (OCH2CF3) groups, and wherein n may vary from at least about 40 to about 100,000, as disclosed herein. Alternatively, one may use derivatives of this polymer as described herein. The term “derivatives” is meant to refer to polymers made up of monomers having the structure of formula I but where one or more of the R1 to R6 functional group(s) is replaced by a different functional group(s), such as an unsubstituted alkoxide, a halogenated alkoxide, a fluorinated alkoxide, or any combination thereof, or where one or more of the R1 to R6 is replaced by any of the other functional group(s) disclosed herein, but where the biological inertness of the polymer is not substantially altered.
In one aspect of the polyphosphazene of formula (I) illustrated above, for example, at least one of the substituents R1 to R6 can be an unsubstituted alkoxy substituent, such as methoxy (OCH3), ethoxy (OCH2CH3) or n-propoxy (OCH2CH2CH3). In another aspect, for example, at least one of the substituents R1 to R6 is an alkoxy group substituted with at least one fluorine atom. Examples of useful fluorine-substituted alkoxy groups R1 to R6 include, but are not limited to OCF3, OCH2CF3, OCH2CH2CF3, OCH2CF2CF3, OCH(CF3)2, OCCH3(CF3)2, OCH2CF2CF2CF3, OCH2(CF2)3CF3, OCH2(CF2)4CF3, OCH2(CF2)5CF3, OCH2(CF2)6CF3, OCH2(CF2)7CF3, OCH2CF2CHF2, OCH2CF2CF2CHF2, OCH2(CF2)3CHF2, OCH2(CF2)4CHF2, OCH12(CF2)5CHF2, OCH2(CF2)6CHF2, OCH2(CF2)7CHF2, and the like. Thus, while trifluoroethoxy (OCH2CF3) groups are particularly useful in some aspects, these further exemplary functional groups also may be used alone, in combination with trifluoroethoxy, or in combination with each other. In one aspect, examples of especially useful fluorinated alkoxide functional groups that may be used include, but are not limited to, 2,2,3,3,3-pentafluoropropyloxy (OCH2CF2CF3), 2,2,2,2′,2′,2′-hexafluoroisopropyloxy (OCH(CF3)2), 2,2,3,3,4,4,4-heptafluorobutyloxy (OCH2CF2CF2CF3), 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxy (OCH2(CF2)7CF3), 2,2,3,3,-tetrafluoropropyloxy (OCH2CF2CHF2), 2,2,3,3,4,4-hexafluorobutyloxy (OCH12CF2CF2CHF2), 3,3,4,4,5,5,6,6,7,7,8,8-dodecafluorooctyloxy (OCH2(CF2)7CHF2), and the like, including combinations thereof.
Further, in some aspects, 1% or less of the R1 to R6 groups may be alkenoxy groups, a feature that may assist in crosslinking to provide a more elastomeric phosphazene polymer. In this aspect, alkenoxy groups include, but are not limited to, OCH2CH═CH2, OCH2CH2CH═CH2, allylphenoxy groups, and the like, including combinations thereof. Also in formula (I) illustrated herein, the residues R1 to R6 are each independently variable and therefore can be the same or different.
Typically, at least one of the groups R1 to R6 in the polymer used is an alkoxy group, substituted with at least one fluorine atom.
Substrates
In one particular aspect of this disclosure, the biocompatible polymer according to Formula (I) is provided as a coating on the substrate to develop the forming surface. In this aspect, there is no particular limitation on the substrate used, and it can be any material, such as a plastic, a polymer or co-polymer, a rubber material, a metal, a metal alloy, a ceramic, an elastomer, an elastomeric membrane, a fabric, a polysaccharide, a glass, or any combination thereof, such as a composite. Moreover, there is no particular limitation on the shape or the size of the substrate. For example, the substrate can be in the form of an object of any desired shape, a surface, a sheet, a mesh, a tube, a tearable material, a scaffold, a perforated material, a sphere, a polyhedron, a surface with raised areas, and the like. The biocompatible coating has, for example, a thickness from about 1 nm up to about 1000 μm, from about 1 nm up to about 10 μm, and from about 1 nm up to about 1 μm. In another aspect, the substrate having a forming surface is a shaped object or molding or molded article made of the biocompatible material according to formula (I).
Adhesion Promoters
In another aspect of this disclosure, an intermediate layer that contains an adhesion promoter, a the layer, or a transitional material is placed between the surface of the substrate and the biocompatible coating that contains a polyphosphazene compound or derivative. The adhesion promoter may improve the adhesion of the coating to the surface of the substrate by coupling of the adhesion promoter to the surface of the substrate through ionic and/or covalent bonds, for example, and by further coupling of the adhesion promoter to the described polymer of formula (I) of the coating, for instance, through ionic and/or covalent bonds. In this aspect, depending on the nature of the substrate and its intended application, a substrate first may be cleaned if desired, for example, by ultrasonication or by immersing the substrate material into various liquid chemical cleaning baths, solutions, or reagents, followed by rinsing with an appropriate solvent based on the particular cleaning bath. Examples of cleaning reagents include, but are not limited to, oxidizing, acidic, or alkaline etching solutions. After several such cleaning steps, substrates then may be immersed in solutions containing a surface reactive adhesion promoter, for a time period sufficient to afford the desired mono- or multilayers of the adhesion promoter on the substrate. Typically, excess, unreacted reagents may be removed by further cleaning, which can be followed by a final drying step.
In one aspect, the adhesion promoter can comprise an acid component and an amine component. The acid component and the amine component can be situated in different substances, materials, or molecules, or within a single substance, material, or molecule. For example, the orientation of the adhesion promoter components relative to the substrate and the phosphazene polymer may be represented generally by the connectivity: substrate-acid component-amine component-polyphosphazene. In this aspect, the acid component can comprise any moiety that provides an acid functionality and can be selected from, for example, acids, esters thereof partial esters thereof, or acid halides, which form hydroxyl (OH−) groups upon hydrolysis with water. Examples of materials that provide acid components include, but are not limited to, carboxylic acids, phosphoric or phosphonic acid derivatives, sulfuric or sulfonic acid derivatives, orthosilic acid derivatives, boronic acid derivatives, titanic acid derivatives, and all other known species, compounds, compositions, mixtures, or moieties that are known to form OH− groups upon hydrolysis with water. In this aspect, the linkage with the amine (or amidine) component may be established by, for example, a typical amide linkage which results from the reaction of the acid component with the free amine and subsequent dehydration. In another aspect, the amide linkage also may be established with the elimination of halide groups instead of hydroxyl, when the acid component comprises an acid halide. While not intending to be bound by theory, the substrate-acid component linkage itself may established by ether formation or hydrogen bonding, or by any method by which the acid moiety or component may interact effectively with the substrate. In another aspect, for example, amino acids are useful as adhesion promoters and provide prototypical examples of molecules in which the acid component and the amine component are situated within a single molecule.
Further to this aspect, the adhesion promoter or spacer can contain a polar end-group, examples of which include, but are not limited to, hydroxy, carboxy, carboxyl, amino, nitro groups, and the like. Further, end groups can be selected from alkoxy, alkylsulfonyl, dialkylamino, aryloxy, heterocycloalkyl having nitrogen as a hetero atom, or heteroaryl having nitrogen as a hetero atom, any of which having up to about 20 carbon atoms, and any of which can be variously substituted, for instance by halogen atoms such as chlorine or fluorine. In this aspect, fluorine-substituted polar end groups work well. The adhesion promoter can, for example, be an amino-terminated silane or one based on aminosilane, amino-terminated alkenes, nitro-terminated alkenes and silanes, or an alkylphosphonic acid.
In one aspect, aminoalkyltrialkoxysilanes such as aminopropyltrialkoxysilanes work well as adhesion promoters when used in combination with polyphosphazenes, examples of which include compounds according to formulas II and III, illustrated here.
In formulas II and III, R7 can be selected independently from —Oalkyl), —O(alkyl) ester, or alkyl; R8 can be selected independently from —O(alkyl); R9 can be selected independently from H or alkyl; and R10 can be selected independently from H or alkyl, wherein alkyl is defined herein, and wherein at least one of R7 or R9 comprises a hydrolyzable —O(alkyl) group. Because at least one of R7 or R8 comprises a hydrolyzable group, a hydrolysis reaction can occur to form a covalent surface grafting. In formulas II and III, m can be an integer from 0 to about 20, and m is typically an integer from 2 to 12, with m being 3 being typical. Also in formulas II and III, n can be an integer from 0 to 4, with n typically being selected from 1 or 2. In one aspect, R9 and R10 can both be H, or in another aspect, R9 and R10 can both be CH3, wherein m is 3 and n is either 1 or 2. While not intending to be bound by theory, it is believed that pendant groups of the siloxane adhesion promoter that have a positive dipole or quadrupole moment, whether temporary or permanent, create a favorable interaction with the negatively polarized fluorinated pendant groups of the polyphosphazene, including fluorinated alkoxide groups such as trifluoroethoxy. For example, pendant groups such as dimethylacetamido, trimethylureido, pentafluorophenyl, quaternary amines, ternary, secondary, primary amines and alkylated amides and the like, exhibit favorable adhesion.
In another aspect of this disclosure, the adhesion promoter can be an organosilicon compound, such as an amino-terminated silane, or based on aminosilane, amino-terminated alkenes, nitro-terminated alkenes, and silanes, or an alkylphosphonic acid. Concerning the various silane-based adhesion promoters, these can include ureido- and glycidyl-terminated silanes which are especially useful for bonding of epoxy resins, thiol or acroyl termini which can be employed for bonding to vinylogous and acrylate based rubbers, or other substrates disclosed herein. For fluoroelastomers, amine and perfluoro based silanes are generally used. Other examples of silane-based adhesion promoters include N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, bis[(3-trimethoxysilyl)propyl]-ethylene diamine, and other commercially-available functional silane reagents. In one aspect, a particularly useful silane-based adhesion promoter is (3-aminopropyl)trimethoxysilane (APTMS).
In various other aspects, an exemplary compound with a pentafluorophenyl pendant group can include the following compound of formula IV, which exhibits favorable silanole end groups, and in which R7 and R8 are the same as their definition for formulas II and III.
Thus, in formula IV, R7 can be selected independently from —O(alkyl), —O(alkyl) ester, or alkyl; R8 can be selected independently from —O(alkyl); wherein alkyl is defined herein, and wherein at least one of R7 or R8 comprises a hydrolyzable —O(alkyl) group.
A comparison of the respective hydrolysis rates for the analogous —O(alkyl) series of adhesion promoters that differ only by R7 and R8, wherein R7 and R8 are selected from OMe, OEt, or OPr, reveals a decreasing hydrolysis rate as one progresses from OMe to OPr. For example, an (OMe)3-terminated silane will hydrolyze 70 times faster than an (OEt)3 endcapped silane in acidified aqueous methanol. Therefore the choice of silane end groups can be adapted to meet desired reaction times. Unless slower reaction times are desired, (OMe)3-substituted silanes are very useful and are typically used.
A further aspect of the disclosure is provided by additional silane adhesion promoters, that are suitable for a gas-phase deposition processes, examples of which are provided as formulas V and VI.
For example, in formulas V and VI, R7 can be selected from —O(alkyl) or alkyl; and R8 can be selected from H or alkyl. Adhesion promoters of formulas V and VI, are suited for both liquid phase and gas phase silane deposition methods, regardless of whether the environment is aqueous or anhydrous. Thus, in one aspect, these adhesion promoters do not need to hydrolyze before being able to react with a hydroxyl rich surface. For example, and while not intending to be bound by theory, formulas V or VI may initiate a ring-opening sequence by reacting with surface bound hydroxyl groups immediately on contact to yield the open-chain variants. Further, reactions rates of the adhesion promoters are convenient. As described herein, such surface modifications may be performed in liquid phase, using etchants, oxidizing solutions, volatile solvents and other reactive species. Moreover, this method employing the adhesion promoters affords a homogeneous and smooth deposition of the adhesion promoter, and film thicknesses also will depend on the concentration and deposition time of the adhesion promoter.
Biological Material
The term “biological material” includes, for example, eucaryotic cells, monolayer or multilayer cellular aggregations, tissues, or cell components of mammals, especially of human origin. In one aspect, the donor of the biological starting material is identical to the recipient of the implantable biological material. Examples of the biological starting material or biological material include endothelial cells of various origins (for example, from skin, foreskin, blood vessels such as the aorta, fatty tissues, eye, omentum, umbilical cord, varices, or the like), epithelial cells of various origins (for example, from the stomach, intestine, or the like), bone cells, cartilage cells, and all adherent cells or cells in which adherence is inducible, cell aggregations or tissues (for example, artificial cultured skin or similar tissue), natural tissues, proteins, sugar molecules and lipids. Artificial organs, blood vessels, bones, cartilage, myelin sheaths, and the like, can be produced by using the substrate with a forming surface, as disclosed herein.
A further aspect of the present disclosure concerns a process for producing the substrates with forming surface as defined above; wherein the application of a coating of the biocompatible polymer according to Formula (I) to the surface of a shaping body, molding (or molded article) or supporting substrate is known from the prior art.
In a further aspect, for example, the substrate with a forming surface can be produced according to the following general procedure.
(a) A solution containing at least one compound of the general Formula (I) at a concentration of 0.1%-99% is prepared, typically in a polar organic solvent. Ethyl acetate, various other ketones, acetone, THF, toluene, or xylenes, for example, can be used here as solvents. Mixtures of these solvents are also usable, or they can be supplemented by other solvents. This solution is applied to a substrate that exhibits little if any adhesion to the polymer, such as glass, silicon, various ceramics or other appropriate materials such as polymers (PDMS, Teflon, PMMA, polycarbonate or silicone). The surfaces of the substrates listed can also be chemically modified, for instance, by introducing certain functional groups (—NH2, —OH, —COOH, —COH, —COOMe, —CF3, and the like).
(b) Evaporation of the solvent can proceed without further measures; but in the best case the concentration of the solvent vapor over the substrate is controlled, as are the pressure and the temperature. At the beginning of the first phase of drying, the atmosphere over the coated substrate should be saturated with solvent vapor, with the concentration of the solvent vapor then being reduced slowly over many hours. The temperature can vary from −30° C. to +90° C. The pressure can follow a gradient from normal pressure to water aspirator vacuum (20 Torr) during the first phase of drying. After the first phase of drying, the coated substrate is further dried for a certain period at oil pump vacuum (0.1 Torr).
The substrate coated with the biocompatible polymer according to Formula (I) can then be used directly, without or after appropriate sterilization. Various coating thicknesses from about 0.1 μm to about 300 μm or even thicker, from about 0.5 μm to about 30 μm, from about 1 μm to about 10 μm, or from about 2 μm to about 7 μm can be obtained, depending on the concentration of the polymer solution and the conditions used during the first phase of drying.
Another aspect of this disclosure concerns a substrate with a micro-structured surface comprising at least partly a biocompatible polymer according to Formula (I) as defined above, with the size or magnitude of the surface structures being in the range of nanometers, micrometers, or even larger or smaller, generally in the range of 10 nm to 100 μm. In one aspect, the biocompatible polymer is present on the substrate as a coating with an externally micro-structured surface.
The structuring of the surface is not subject to any particular limitation. For instance, all structures that can be generated photolithographically, with an electron beam, with an ion beam with a laser, or by other techniques, can be produced. The microstructuring of the surface of the substrate or of the coating can also be obtained by “fusion structuring or melt structuring”, in which a thin wire is brought to the melting temperature of the biocompatible polymer and then melts the desired structure into the surface of the coating by direct contact.
Special advantages can be attained by means of this structuring with structures that affect the flow behavior of liquids particularly favorably (for example, sharkskin or lotus effect) imprinted into the surface of the coating or substrate.
Cellular Growth on Micro-Structured Surfaces
One aspect of this disclosure provides a method for the gradual adjustment or tuning of the cellular response to a polyphosphazene micro-structured substrate, from a cellular adhesion and proliferation response regime to a cellular repulsion regime. In one aspect, such a tailored response can be obtained on the basis of the selected phosphazene micro-structure size range, for example, the size, concentration, and structures of the pores of the polyphosphazene coating. These structural features of the pores can depend from, among other things, the concentrations of the polyphosphazene-containing solution used to contact the substrate. Generally, at higher polyphosphazene concentrations, the cellular repulsion regime can be accessed, as evidenced by elongated structures of the cellular motile mode. However, at lower polyphosphazene concentrations, including uncoated substrates, a cellular adhesion and proliferation response regime can be accessed, as evidenced by the reduction of cellular spreading and reduced cell motility.
Moreover, a continuum of intermediate regimes or types of cellular proliferation and growth can be accessed with the methods of this disclosure. For example, an intermediate regime of moderate cellular attraction can be obtained, from moderate attraction to moderate repulsion, which can be obtained on the basis of the decrease of spacing density of the void structure within the polyphosphazene micro-structure, and thus the effective surface coverage of the polyphosphazene micro-structure. In addition, desired cellular response can be correlated with the polyphosphazene surface coverage and the spacing density of the structural element (such as pores), both of which can be related to the polyphosphazene film thickness and adjusted or tuned by the polyphosphazene coating solution concentration. Thus, lower polyphosphazene concentrations provide lower surface coverage and lower film thickness, along with a higher spacing density of the structural element, and results in greater cellular attraction. Similarly, higher polyphosphazene concentrations provide higher surface coverage and greater film thickness, along with a lower spacing density of the structural element, all resulting in greater cellular repulsion.
Accordingly, cellular attraction to an adhesion promoter-treated surface can be obtained by Polyzene®-F surface coverage of from about 74% to about 88.5% and any range in between, a spacing density of the pore structural element of from about 2150 per 100 μm2 to about 950 per 100 μm2, and a Polyzene®-F film thickness of from 0 to about 20 nm. In contrast, cellular repulsion at an adhesion promoter-treated surface can be obtained by Polyzene®-F surface coverage of from about 97% and higher, for example from 97% to about 97.5%, a spacing density of the pore structural element of from about 200 per 100 μm2 to about 150 per 100 μm2, and a Polyzene®-F film thickness of from about 175 nm to about 290 nm. A continuum of cellular responses from moderate attraction to moderate repulsion can be obtained at intermediate values. Thus, the introduction of nanometer sized voids, for example, from about 10 nm up to about 0.5 μm-sized voids as structural elements in the polyphosphazene micro-structure, enables the cells to attach to the underlying substrate, the spacing density of which controls the cellular attachment behavior. The average pore size diameter is from about 75 nm to about 150 nm.
In a further aspect of the disclosure, for specific cell growth applications, the target substrate material, the optional adhesion promoter layer and the micro-structured polyphosphazene coating (and/or combinations and permutations thereof may specifically be chosen to create a blend or a gradient implant superstructure, which favorably combines and/or mixes the desired cellular response properties of base substrate material, adhesion promoter layer and polyphosphazene coating, in order to achieve a targeted or selective cellular response. For example a combination of cellular adhesion, cellular growth, cellular proliferation, and cellular differentiation on the newly formed implant surface may be obtained with such a blend or gradient implant superstructure. Such a combination is not limited to physical (cellular) perception only, but may also include the formation of chemically contrasted structures, that is, containing an inherent, spatially-resolved, selectivity or affinity for a variety of chemical, biological, and/or pharmaceutical agents to further enhance the desired biological and cellular response. For instance, as illustrated in Example 2, a gradual decrease of cellular adhesion and cell spreading on such a gradient structure can be obtained, where a purely cell-adhesive APTMS surface is gradually converted into a cellular-repulsive surface by applying a polyphosphazene micro-structuring technique and coating.
In another aspect of this disclosure, Table 2 of Example 2 summarizes some examples of coating and structural parameters that can be used to attain a desired cellular response on a micro-structured substrate. General information on the cellular repulsive behavior arising from thick poly[bis(2,2,2-trifluoroethoxy)phosphazene] films (typically >1 μm range) for particular cell lines, are illustrated as follows: SK-N-BE(2c) human neuroblastoma cell line (see Eric Barrett et al., Biomacromolecules 2005, May-June, 6(3), pp. 1689-97); L929 mouse fibroblasts, hepatoma cell line HepG2 (see Alexander Welle, J. Biomater. Sci. Polymer Edn. 2004, Vol. 15, No. 3, pp. 357-3700; HeLa cells, cervical cancer cell line (see Yoshi Hori et al., Artificial Organs, 26(10):868-893 (2002)); and thrombocytes, erythrocytes and E. coli (Dr. Claudia Gries, Dissertation, University of Heidelberg, 2001). Other aspects of this disclosure are provided in Cato T. Laurencin, et al., Journal of Biomedical Materials Research, Vol. 27, 963-973 (1993). Each of these references is incorporated herein by reference in their entireties.
The present disclosure is further supported and illustrated by the following examples, which are not to be construed in any way as imposing limitations upon the scope thereof. On the contrary, it is to be clearly understood that resort can be had to various other aspects, embodiments, modifications, and equivalents thereof which, after reading the description herein, can suggest themselves to one of ordinary skill in the art without departing from the spirit of the present disclosure or the scope of the appended claims.
Unless indicated otherwise, temperature is reported in degrees Centigrade and pressure is at or near atmospheric. An example of the preparation of a polyphosphazene of this disclosure is provided with the synthesis of poly[bis(trifluoroethoxy)phosphazene] (PzF) polymer, which may be prepared according to U.S. Patent Application Publication No. 2003/0157142, the entirety of which is hereby incorporated by reference. Other disclosures of phosphazene syntheses are provided in S. V. Vinogradova, D. R. Tur, and V. A. Vasnev, Russian Chemical Reviews, vol. 67(6), 515-534 (1998) (translated from Uspekhi Khimii vol 67(6), 573-594 (1998)), which is incorporated by reference in its entirety. Accordingly, any polyphosphazene encompassed in this disclosure and having R1 through R6 as defined herein, can be prepared according to the of phosphazene synthesis methods disclosed in, for example, the Vinogradova et al. publication. In additional, the synthetic procedures by which the polyphosphazenes employed in this disclosure can be made also are disclosed in Allcock, Harry R., “Poly(organophosphazenes)-Unusual New High Polymers,” Angew. Chem. Int. Ed. Engl. 16, 147-156 (1977); and in Allcock, Harry R., “Chemistry and Applications of Polyphosphazenes,” Wiley-Interscience (2002) (ISBN-10: 0471443719; ISBN-13: 978-0471443711); both of which are incorporated herein by reference in their entireties.
Also unless indicated otherwise, when a range of any type is disclosed or claimed, for example a range of molecular weights, layer thicknesses, concentrations, temperatures, and the like, it is intended to disclose or claim individually each possible number that such a range could reasonably encompass, including any sub-ranges encompassed therein. For example, when the Applicants disclose or claim a chemical moiety having a certain number of atoms, for example carbon atoms, Applicants' intent is to disclose or claim individually every possible number that such a range could encompass, consistent with the disclosure herein. Thus, by the disclosure that an alkyl substituent or group can have from 1 to 20 carbon atoms, Applicants intent is to recite that the alkyl group have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms. In another example, by the disclosure that the particular spacing density of a structural element can be from 200 to 150 voids/100 μm2, Applicants include within this disclosure the recitation that the particular spacing density of a structural element can be approximately 200 voids/100 μm2, approximately 190 voids/100 μm2, approximately 180 voids/100 μm2, approximately 170 voids/100 μm2, approximately 160 voids/100 μm2, and/or approximately 150 voids/100 μm2, including any range or sub-range encompassed therein. Accordingly, Applicants reserve the right to proviso out or exclude any individual members of such a group, including any sub-ranges or combinations of sub-ranges within the group, that can be claimed according to a range or in any similar manner, if for any reason Applicants choose to claim less than the full measure of the disclosure, for example, to account for a reference that Applicants are unaware of at the time of the filing of the application.
All publications, patents, and documents mentioned in the disclosure are, in relevant part, incorporated herein by reference in their entireties, for the purpose of describing and disclosing, for example, the constructs and methodologies that are described in the publications, which might be used in connection with the presently described process and apparatus. The publications discussed above and throughout the text are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention. Should the usage or terminology used in any reference that is incorporated by reference conflict with the usage or terminology used in this disclosure, the usage and terminology of this disclosure controls. The Abstract of the disclosure is provided herewith to satisfy the requirements of 37 C.F.R. §1.72 and the purpose stated in 37 C.F.R. §1.72(b) “to enable the United States Patent and Trademark Office and the public generally to determine quickly from a cursory inspection the nature and gist of the technical disclosure.” The Abstract is not intended to be used to construe the scope of the appended claims or to limit the scope of the subject matter disclosed herein. Any use of the past tense to describe an example otherwise indicated as constructive or prophetic is not intended to reflect that the constructive or prophetic example has actually been carried out.
The following Examples provide, among other things, experimental evidence for the measurable effect of polyphosphazene surface structure dimensions on cell proliferation and growth. Examples are provided for the preparation of micro-structured polyphosphazene coatings, and for cell proliferation and growth on target surfaces prepared according this disclosure. Examples will also show that, within the spatial range, aspect ratio, and size or magnitude (lateral and height dimensions) of the polyphosphazene micro-structures, the cellular response can be gradually turned from a cellular adhesion and proliferation regime to one of cellular repulsion, the targeted cellular response of which will be depending on the designed and selected phosphazene micro-structure size range.
Sample glass substrates having the dimensions 20 mm×20 mm×0.1 mm were pre-cleaned with Caro's acid [(H2SO4 (96%): H2O2 (30%) in a 3:1 (v/v) ratio)] for a period of 30 minutes, rinsed with copious amounts of ultrapure water, and dried under a stream of Argon to afford chemically clean substrate surfaces.
The cleaned glass substrates from Example 1a were used in this procedure. The protocol of Stenger et al. (D. A. Stenger, J. H. Georger, C. S. Dulcey, J. J. Hickman, A. S. Rudolph, T. B. Nielsen, S. M. McCort, and J. M. Calvert, J. Am. Chem. Soc. vol. 114, 8435-8442, (1992)) was used for the deposition of an adhesion promoter, as is described for aminopropyltrimethoxysilane [APTMS, (MeO)3SiCH2CH2CH2NH2]. A stock “silanization” solution of 500 mL of 95% methanol and 5% ultrapure water (v:v) was acidified by adding 29 μL of glacial acetic acid, which aids in the hydrolysis of the silane. Once the APTMS solution was prepared, 1 part per volume of the 3-aminopropyltrimethoxysilane was added to 99 parts per volume of this APTMS solution.
Previously cleaned glass substrates were immersed in this solution and maintained or “incubated” for a period of 2 h. After incubation, samples were subjected to ultrasonication in absolute methanol for 10 min, removed and rinsed with pure methanol, and blown dry under a Stream of argon. The resulting aminopropylsiloxane multilayers were cured or crosslinked by drying in an oven for 1 h at 105° C., then allowed to cool to ambient temperature. After cooling, samples were stored under argon until further used.
The APTMS-coated glass slides prepared according to Example 1b were spin-coated with poly[bis(2,2,2-trifluoroethoxy)phosphazene] (Polyzene®-F) having a molecular weight of about 14.7×106 g/mol, which corresponds to a degree of polymerization based on formula I of n=60,500. This sample of poly[bis(2,2,2-trifiluoroethoxy)phosphazene] was characterized by 1H NMR, 13C NMR, 31P NMR, Infrared (IR) spectroscopy, viscosimetry, and GPC analysis. Spin-coating was carried out using Polyzene®-F solutions ranging in concentration of about 0.5-20 mg/mL in methylisobutylketone, at a speed of about 3000 rpm for a period of 60 seconds. This coating procedure provided Polyzene®-F coatings ranging in thickness from about 1 nm up to about 0.5 μm, and having a decreasing gradient of a heterogeneous substrate-film open-cell porous micro-structure. Coatings ranging in thickness from about 1 nm up to about 0.5 μm can be prepared using this technique by adjusting variables such as spin rate and time, Polyzene®-F solution concentration, and the like, as understood by one of ordinary skill in the art. Poly[bis(2,2,2-trifluoroethoxy)phosphazene] (Polyzene®-F) is described in formula I, in which each of R1 through R6 is 2,2,2-trifluoroethoxy (—OCH2CF3). As understood by one of ordinary skill, the molecular weight of about 13×106 g/mol used for this Polyzene®-F coating can be an indicator of the film thickness that can be achieved in this coating process.
The micro-structured polyphosphazene coatings prepared according to Example 1c were characterized to study the effect of surface micro-structure and film dimensions on cell attachment, proliferation, and growth. Accordingly, films were characterized by Atomic Force Microscopy (AFM) and Optical Ellipsometry, to obtain correlating data for film thickness and film micro-structure morphology, as follows.
According to the data presented in
The Polyzene®-F micro-structured films prepared according to Example 1C were further evaluated with AFM and Optical Ellipsometry to assess the film thickness range and refractive index. These data are presented in Table 1.
Error values of the AFM measurements presented in Table 1 were based on the root-mean-square roughness of the Polyzene®-F films. As illustrated, the different techniques used to measure thickness yielded comparable results. In addition, the ellipsometric measurements showed a clear increment in the refractive index as the film thickness increased.
These numeric findings supplement the micro-structure morphology information obtained with AFM. Surface morphologies obtained in Example 1c indicated a varying degree of porosity in the polymer films. As the refractive index reaches a value of n=1.39 (at ≧20/mg/mL Polyzene®-F concentration), the polymer film is becoming free of voids beyond this regime. Hence, the measured refractive index can be interpreted as the effective sum of the respective refractive indices of bulk Polyzene®-F polymer (n=1.39) and pure air (n=1). This information shows that the pores are open cell structures void of phosphazene polymer, exposing the APTMS substrate underneath. Therefore, the higher the concentration of the polymer in the spin-coating solution, the closer the index of refraction of the coating to that of the polymer itself is observed.
A pore size analysis also was conducted to further investigate the relative pore count and percentage of surface coverage obtained with the polyphosphazene micro-structuring technique of Example 1c.
Accordingly, the following conclusions can be drawn from the information illustrated in
A) Within the boundaries of Example 1c, the polyphosphazene film thickness dimensions ranged from 0 nm to about 0.3 μm (300 nm). This range works well for the targeted tailoring of cellular adhesion to the micro-structured substrate, and can be achieved by altering the concentration of the Polyzene®-F spin-coating solution. The film deposition technique employed in Example 1c allows for the formation of even higher film thicknesses, for example up to about 10 μm or even up to 100 μm or greater, if higher polymer concentrations and other parameters are used. The film deposition technique employed in Example 1c also allows for tailoring the film thickness as desired with a substantial measure of control. Although there is no theoretical limit as to the upper boundary for film thickness, particularly desirable ranges are typically up to about 1 μm for the techniques described in this disclosure. Thus, the effective film thickness range that provides for modulation of cellular response by this structuring technique can be obtained according to this disclosure. The lateral film dimensions of the film are not limited by the deposition technique and the lateral substrate dimensions can easily exceed the centimeter range. Any suitable coating technique for the soluble polymer, as known to one of ordinary skill can be employed to coat a wide variety of substrates of varying sizes.
B) The open-cell porous polyphosphazene micro-structures created by using the micro-structuring technique of Example 1c afforded a lateral spacing density of from 0 pores up to about 2500 pores per 100 μm2 surface area, having a pore size range of from 0 nm to about 0.5 μm in diameter. The average pore size range is typically in the range from about 75 to about 150 nm in diameter. The effective surface area covered by the polyphosphazene micro-structure, within the parameters described in Example 1c, ranged from approximately 74% to about 100% effective surface area covered.
Examples 1a and 1b of the present disclosure can be repeated using a variety of substrates. For example, a range of substrates may be employed according to this disclosure, including but not limited to, any plastic or polymeric material, any metal or metal alloys, or any ceramic material. Crystalline or non-crystalline substrate materials can be employed as well.
Example 1b of the present disclosure also can be repeated using a variety of adhesion promoters. For example, a range of adhesion promoters with a polar end group may be employed, examples of which include but are not limited to hydroxy, carboxy, carboxyl, amino, or nitro end groups. Further, end groups can be selected from alkoxy, alkylsulfonyl, dialkylamino, aryloxy, heterocycloalkyl having nitrogen as a hetero atom, or heteroaryl having nitrogen as a hetero atom, any of which having up to about 20 carbon atoms, and any of which can be variously substituted, for instance by halogen atoms, including fluorine. The adhesion promoter can, for example, be an amino-terminated silane or one based on aminosilane, amino-terminated alkenes, nitro-terminated alkenes and silanes, or an alkylphosphonic acid.
In a further aspect, Example 1 can be carried out using APTMS-coated glass slides prepared according to Example 1b, which can be spin-coated with poly[bis(2,2,2-trifluoro-ethoxy)phosphazene] (Polyzene®-F) having a molecular weight ranging from about 12×106 g/mol to about 18×106 g/mol.
Example 2 demonstrates how that, within the lateral and height dimension ranges of the polyphosphazene micro-structures tailored and prepared according to Example 1, the cellular response to a polyphosphazene-micro-structured substrate can be gradually adjusted or tuned from a cellular adhesion and proliferation response regime to a cellular repulsion regime, in which the targeted cellular response depends upon the desired phosphazene micro-structure size range.
This example relates to fibroblast cellular adhesion studies on Polyzene®-F coated substrates. Fibroblast cellular adhesion, proliferation and spreading were studied in an in vitro cell culture experiment on the surfaces prepared according to Example 1, in which it was observed that the fibroblast cells exhibited a concentration-dependent adhesion behavior. For a Polyzene®-F spin-coating solution concentration range of from 0 mg/mL to about 2 mg/mL Polyzene®-F, no concernible difference between coated and uncoated APTMS glass reference substrates was observed. Thus, as illustrated in
The data from these figures illustrates that the threshold for the transition or change of cellular adhesion and proliferation behavior occurred between about 4 mg/mL and about 6 mg/mL Polyzene®-F, which corresponds to a Polyzene®-F film thickness of 20-65 nm. Below this threshold, cellular adhesion and proliferation behavior resembles that of the APTMS substrate, and fibroblast cells were found to spread.
An intermediate regime of moderate attraction was observed from about 65 nm up to about 175 nm, followed by an intermediate regime of moderate repulsion from about 175 nm to about 290 nm, which is related to the decrease of spacing density of the void structure within the polyphosphazene micro-structure, and thus the effective surface coverage thereof. As illustrated in the data in Table 2, the complete range of Polyzene®-F surface coverage is from about 74% to about 100% surface coverage, as shown in
Above this threshold, the Polyzene®-F micro-structure is devoid of pores or voids and the Polyzene®-F film is clearly cell-repulsive, as shown in Table 2, and
These cellular adhesion and repulsion studies and how cellular adhesion and repulsion can be modulated, can be summarized in the data provided in Table 2, which summarizes data from the figures provided herein. For example, the surface coverage and the desired cellular response are extrapolated from
The introduction of nanometer sized voids, for example, from about 10 nm up to about 0.5 μm-sized voids as structural elements in the polyphosphazene micro-structure, enables the cells to attach to the underlying substrate, the spacing density of which controls the cellular attachment behavior. The average pore size diameter is from about 75 nm to about 150 nm.
Full cellular repulsion is observed on completely closed, spherulitic domain structures substantially devoid of pores. In this case, the lateral domain size of the spherulites is in the about 10 μm to about 100 μm range.
On the basis of these data, it is concluded that the number of attached cells and their morphology depended on the coating concentration initially used for the preparation of the coated samples, and thus was directly related to the Polyzene®-F film thickness and micro-structure morphology, that is, the surface area covered by Polyzene®-F and the lateral spacing density of the pores.
Example 3 illustrates the effect of adhering a biologically active biomacromolecule with a specific selectivity towards Polyzene®-F to an otherwise cell-repulsive polyphosphazene micro-structure, to completely revert the cellular attachment and spreading behavior.
Polyzene®-F coated substrates prepared according to Example 1 were pre-treated with a 50 μg/mL fibronectin (FN) solution to afford selective adsorption of the biologically active macromolecule. A cell seeding experiment analogous to that of Example 2 was repeated. The results of this study are illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 101 00 961 | Jan 2001 | DE | national |
This application is a continuation-in-part of U.S. patent application Ser. No. 10/250,985, of which is now U.S. Pat. No. 8,007,821 which is a 35 U.S.C. §371 National Stage filing application of PCT Application No. PCT/EP02/00230, filed Jan. 11, 2002, which claims priority to German patent No. DE 101 00 961.5, filed Jan. 11, 2001, the entire disclosures of which are incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3949073 | Daniels et al. | Apr 1976 | A |
| 4107288 | Oppenheim et al. | Aug 1978 | A |
| 4124705 | Rothman et al. | Nov 1978 | A |
| 4166800 | Fong | Sep 1979 | A |
| 4311736 | Leong | Jan 1982 | A |
| 4318947 | Joung | Mar 1982 | A |
| 4341844 | Leong | Jul 1982 | A |
| 4373217 | Draenert | Feb 1983 | A |
| 4424208 | Wallace et al. | Jan 1984 | A |
| 4424395 | Strom | Jan 1984 | A |
| 4440750 | Glowacki et al. | Apr 1984 | A |
| 4451647 | Allcock et al. | May 1984 | A |
| 4452916 | Boschetti | Jun 1984 | A |
| 4480642 | Stoy et al. | Nov 1984 | A |
| 4507123 | Yoshida | Mar 1985 | A |
| 4535485 | Ashman et al. | Aug 1985 | A |
| 4537916 | Bruschtein et al. | Aug 1985 | A |
| 4547390 | Ashman et al. | Oct 1985 | A |
| 4557764 | Chu | Dec 1985 | A |
| 4565580 | Miyata et al. | Jan 1986 | A |
| 4579880 | Ohashi | Apr 1986 | A |
| 4582640 | Smestad et al. | Apr 1986 | A |
| 4592755 | Penton et al. | Jun 1986 | A |
| 4595713 | St. John | Jun 1986 | A |
| 4677173 | Holle et al. | Jun 1987 | A |
| 4698373 | Tateosian et al. | Oct 1987 | A |
| 4728570 | Ashman et al. | Mar 1988 | A |
| 4798876 | Gould et al. | Jan 1989 | A |
| 4803075 | Wallace et al. | Feb 1989 | A |
| 4837285 | Berg et al. | Jun 1989 | A |
| 4849285 | Dillon | Jul 1989 | A |
| 4851046 | Low et al. | Jul 1989 | A |
| 4880622 | Allcock et al. | Nov 1989 | A |
| 4883699 | Aniuk et al. | Nov 1989 | A |
| 4902511 | Kronman | Feb 1990 | A |
| 4911691 | Aniuk et al. | Mar 1990 | A |
| 4912141 | Kronman | Mar 1990 | A |
| 4975280 | Schacht et al. | Dec 1990 | A |
| 4999188 | Solodovnik et al. | Mar 1991 | A |
| 5007940 | Berg | Apr 1991 | A |
| 5019400 | Gombotz et al. | May 1991 | A |
| 5077049 | Dunn et al. | Dec 1991 | A |
| 5116387 | Berg | May 1992 | A |
| 5137875 | Tsunenaga et al. | Aug 1992 | A |
| 5142008 | Holle et al. | Aug 1992 | A |
| 5143724 | Leshchiner et al. | Sep 1992 | A |
| 5158573 | Berg | Oct 1992 | A |
| 5162430 | Rhee et al. | Nov 1992 | A |
| 5204382 | Wallace et al. | Apr 1993 | A |
| 5238569 | Soria et al. | Aug 1993 | A |
| 5258028 | Ersek et al. | Nov 1993 | A |
| 5278201 | Dunn et al. | Jan 1994 | A |
| 5278202 | Dunn et al. | Jan 1994 | A |
| 5292802 | Rhee et al. | Mar 1994 | A |
| 5294446 | Schlameus et al. | Mar 1994 | A |
| 5304595 | Rhee et al. | Apr 1994 | A |
| 5306500 | Rhee et al. | Apr 1994 | A |
| 5308701 | Cohen et al. | May 1994 | A |
| 5324775 | Rhee et al. | Jun 1994 | A |
| 5342557 | Kennedy | Aug 1994 | A |
| 5344452 | Lemperle | Sep 1994 | A |
| 5352715 | Wallace et al. | Oct 1994 | A |
| 5368859 | Dunn et al. | Nov 1994 | A |
| 5395620 | Huc et al. | Mar 1995 | A |
| 5397352 | Burres | Mar 1995 | A |
| 5399351 | Leshchiner et al. | Mar 1995 | A |
| 5413791 | Rhee et al. | May 1995 | A |
| 5428024 | Chu et al. | Jun 1995 | A |
| 5439446 | Barry | Aug 1995 | A |
| 5446091 | Rhee et al. | Aug 1995 | A |
| 5451406 | Lawin et al. | Sep 1995 | A |
| 5456693 | Conston et al. | Oct 1995 | A |
| 5476666 | Rhee et al. | Dec 1995 | A |
| 5487390 | Cohen et al. | Jan 1996 | A |
| 5487897 | Polson et al. | Jan 1996 | A |
| 5494673 | Andrianov et al. | Feb 1996 | A |
| 5494682 | Cohen et al. | Feb 1996 | A |
| 5500161 | Andrianov et al. | Mar 1996 | A |
| 5510418 | Rhee et al. | Apr 1996 | A |
| 5516532 | Atala et al. | May 1996 | A |
| 5529777 | Andrianov et al. | Jun 1996 | A |
| 5548060 | Allcock et al. | Aug 1996 | A |
| 5552159 | Mueller et al. | Sep 1996 | A |
| 5562099 | Cohen et al. | Oct 1996 | A |
| 5562909 | Allcock et al. | Oct 1996 | A |
| 5571182 | Ersek et al. | Nov 1996 | A |
| 5599852 | Scopelianos et al. | Feb 1997 | A |
| 5605696 | Eury et al. | Feb 1997 | A |
| 5624685 | Takahashi et al. | Apr 1997 | A |
| 5633001 | Ågerup | May 1997 | A |
| 5634946 | Slepian | Jun 1997 | A |
| 5635215 | Boschetti et al. | Jun 1997 | A |
| 5639796 | Lee | Jun 1997 | A |
| 5648100 | Boschetti et al. | Jul 1997 | A |
| 5681873 | Norton et al. | Oct 1997 | A |
| 5686425 | Lee | Nov 1997 | A |
| 5707597 | Andrianov et al. | Jan 1998 | A |
| 5716981 | Hunter et al. | Feb 1998 | A |
| 5728752 | Scopelianos et al. | Mar 1998 | A |
| 5733562 | Lee | Mar 1998 | A |
| 5752974 | Rhee et al. | May 1998 | A |
| 5763399 | Lee | Jun 1998 | A |
| 5776193 | Kwan et al. | Jul 1998 | A |
| 5788979 | Alt et al. | Aug 1998 | A |
| 5792478 | Lawin et al. | Aug 1998 | A |
| 5814704 | Andrianov et al. | Sep 1998 | A |
| 5824333 | Scopelianos et al. | Oct 1998 | A |
| 5840290 | Hench et al. | Nov 1998 | A |
| 5840819 | Biensan | Nov 1998 | A |
| 5843172 | Yang et al. | Dec 1998 | A |
| 5855895 | Andrianov et al. | Jan 1999 | A |
| 5873904 | Ragheb et al. | Feb 1999 | A |
| 5886026 | Hunter et al. | Mar 1999 | A |
| 5914388 | Allcock | Jun 1999 | A |
| 5922025 | Hubbard | Jul 1999 | A |
| 5955143 | Wheatley et al. | Sep 1999 | A |
| 5962427 | Goldstein et al. | Oct 1999 | A |
| 5980972 | Ding | Nov 1999 | A |
| 5997301 | Linden | Dec 1999 | A |
| 6007573 | Wallace et al. | Dec 1999 | A |
| 6015563 | Andrianov et al. | Jan 2000 | A |
| 6063061 | Wallace et al. | May 2000 | A |
| 6066325 | Wallace et al. | May 2000 | A |
| 6071530 | Polson et al. | Jun 2000 | A |
| 6077916 | Laurencin | Jun 2000 | A |
| 6083262 | Caravel | Jul 2000 | A |
| 6165489 | Berg et al. | Dec 2000 | A |
| 6190684 | Hench et al. | Feb 2001 | B1 |
| 6203788 | Blaschuk et al. | Mar 2001 | B1 |
| 6207171 | Payne et al. | Mar 2001 | B1 |
| 6210715 | Starling et al. | Apr 2001 | B1 |
| 6214331 | Vanderhoff et al. | Apr 2001 | B1 |
| 6235061 | Laurencin et al. | May 2001 | B1 |
| 6254634 | Anderson | Jul 2001 | B1 |
| 6261323 | Neto | Jul 2001 | B1 |
| 6261325 | de la Mettrie et al. | Jul 2001 | B1 |
| 6261573 | Loebelenz et al. | Jul 2001 | B1 |
| 6270748 | Annan et al. | Aug 2001 | B1 |
| 6273913 | Wright et al. | Aug 2001 | B1 |
| 6277392 | Klein | Aug 2001 | B1 |
| 6281015 | Mooney et al. | Aug 2001 | B1 |
| 6284284 | Naughton | Sep 2001 | B1 |
| 6290981 | Keefer et al. | Sep 2001 | B1 |
| 6309420 | Preissman | Oct 2001 | B1 |
| 6319984 | Song et al. | Nov 2001 | B1 |
| 6335028 | Vogel et al. | Jan 2002 | B1 |
| 6335383 | Scopelianos et al. | Jan 2002 | B1 |
| 6346110 | Wu | Feb 2002 | B2 |
| 6365187 | Mathiowitz et al. | Apr 2002 | B2 |
| 6383500 | Wooley et al. | May 2002 | B1 |
| 6391343 | Yen | May 2002 | B1 |
| 6423332 | Huxel et al. | Jul 2002 | B1 |
| 6423343 | Lee et al. | Jul 2002 | B1 |
| 6431174 | Knudson et al. | Aug 2002 | B1 |
| 6432128 | Wallace et al. | Aug 2002 | B1 |
| 6432437 | Hubbard | Aug 2002 | B1 |
| 6436424 | Vogel | Aug 2002 | B1 |
| 6458387 | Scott et al. | Oct 2002 | B1 |
| 6458889 | Trollsas et al. | Oct 2002 | B1 |
| 6485514 | Wrenn, Jr. | Nov 2002 | B1 |
| 6491903 | Forster et al. | Dec 2002 | B1 |
| 6503556 | Harish et al. | Jan 2003 | B2 |
| 6506411 | Hunter et al. | Jan 2003 | B2 |
| 6530878 | Silverman et al. | Mar 2003 | B2 |
| 6531152 | Lerner et al. | Mar 2003 | B1 |
| 6537574 | Hubbard | Mar 2003 | B1 |
| 6544503 | Vanderhoff et al. | Apr 2003 | B1 |
| 6546936 | Knudson et al. | Apr 2003 | B2 |
| 6555123 | Williams et al. | Apr 2003 | B2 |
| 6558612 | Hubbard | May 2003 | B1 |
| 6569195 | Yang et al. | May 2003 | B2 |
| 6585994 | Williams et al. | Jul 2003 | B2 |
| 6620185 | Harvie et al. | Sep 2003 | B1 |
| 6652575 | Wang | Nov 2003 | B2 |
| 6652873 | Deaver et al. | Nov 2003 | B2 |
| 6660301 | Vogel et al. | Dec 2003 | B1 |
| 6662805 | Frondoza et al. | Dec 2003 | B2 |
| 6666892 | Hiles et al. | Dec 2003 | B2 |
| 6669719 | Wallace et al. | Dec 2003 | B2 |
| 6676971 | Goupil et al. | Jan 2004 | B2 |
| 6680046 | Boschetti | Jan 2004 | B1 |
| 6682760 | Noff et al. | Jan 2004 | B2 |
| 6689823 | Bellare et al. | Feb 2004 | B1 |
| 6699471 | Radice et al. | Mar 2004 | B2 |
| 6713646 | Zhang et al. | Mar 2004 | B2 |
| 6767637 | Park et al. | Jul 2004 | B2 |
| 6790456 | Vogel et al. | Sep 2004 | B2 |
| 6858634 | Asrar et al. | Feb 2005 | B2 |
| 6866860 | Nathan | Mar 2005 | B2 |
| 6869445 | Johnson | Mar 2005 | B1 |
| 6872799 | Nathan | Mar 2005 | B2 |
| 6884905 | Zhang et al. | Apr 2005 | B2 |
| 6916910 | Wolfinbarger, Jr. | Jul 2005 | B2 |
| 6933326 | Griffey et al. | Aug 2005 | B1 |
| 6936271 | Oliver et al. | Aug 2005 | B1 |
| 6949251 | Dalal et al. | Sep 2005 | B2 |
| 6962979 | Rhee | Nov 2005 | B1 |
| 6967234 | Nathan | Nov 2005 | B2 |
| 7004977 | Ashman | Feb 2006 | B2 |
| 7012126 | Matsuda et al. | Mar 2006 | B2 |
| 7025980 | Williams et al. | Apr 2006 | B1 |
| 7025990 | Sawhney | Apr 2006 | B2 |
| 7026374 | Nathan et al. | Apr 2006 | B2 |
| 7053134 | Baldwin et al. | May 2006 | B2 |
| 7053209 | Gibson et al. | May 2006 | B1 |
| 7056277 | Silverman et al. | Jun 2006 | B2 |
| 7057019 | Pathak | Jun 2006 | B2 |
| 7060287 | Hubbard et al. | Jun 2006 | B1 |
| 7060298 | Vogel et al. | Jun 2006 | B2 |
| 7077144 | Knudson et al. | Jul 2006 | B2 |
| 7094369 | Buiser et al. | Aug 2006 | B2 |
| 7129209 | Rhee | Oct 2006 | B2 |
| 7131997 | Bourne et al. | Nov 2006 | B2 |
| 7135593 | Zhang et al. | Nov 2006 | B2 |
| 7144414 | Harvie et al. | Dec 2006 | B2 |
| 7157080 | Radice et al. | Jan 2007 | B2 |
| 7160931 | Cheng et al. | Jan 2007 | B2 |
| 7192984 | Berg et al. | Mar 2007 | B2 |
| 7244270 | Lesh | Jul 2007 | B2 |
| 7249601 | Silverman et al. | Jul 2007 | B2 |
| 7265199 | Grunze | Sep 2007 | B2 |
| 7288319 | Baldwin et al. | Oct 2007 | B2 |
| 7303756 | Bodmeier | Dec 2007 | B1 |
| 7314636 | Caseres et al. | Jan 2008 | B2 |
| 7326172 | Miller | Feb 2008 | B2 |
| 7338657 | Vogel et al. | Mar 2008 | B2 |
| 7922764 | Gordy et al. | Apr 2011 | B2 |
| 8007821 | Grunze | Aug 2011 | B2 |
| 20010014717 | Hossainy et al. | Aug 2001 | A1 |
| 20010027340 | Wright et al. | Oct 2001 | A1 |
| 20010029351 | Falotico et al. | Oct 2001 | A1 |
| 20020005206 | Faletico et al. | Jan 2002 | A1 |
| 20020016637 | Anton | Feb 2002 | A1 |
| 20020051730 | Bodnar et al. | May 2002 | A1 |
| 20020068089 | Vogel et al. | Jun 2002 | A1 |
| 20020094440 | Llanos et al. | Jul 2002 | A1 |
| 20020111590 | Davila et al. | Aug 2002 | A1 |
| 20020119202 | Hunter et al. | Aug 2002 | A1 |
| 20020133183 | Lentz et al. | Sep 2002 | A1 |
| 20020143386 | Davila et al. | Oct 2002 | A1 |
| 20020151466 | Hubbard et al. | Oct 2002 | A1 |
| 20020165608 | Llanos et al. | Nov 2002 | A1 |
| 20020197326 | Vogel et al. | Dec 2002 | A1 |
| 20030004568 | Ken et al. | Jan 2003 | A1 |
| 20030060877 | Falotico et al. | Mar 2003 | A1 |
| 20030065345 | Weadock | Apr 2003 | A1 |
| 20030065377 | Davila et al. | Apr 2003 | A1 |
| 20030099683 | Grunze | May 2003 | A1 |
| 20030140930 | Knudson et al. | Jul 2003 | A1 |
| 20030149490 | Ashman | Aug 2003 | A1 |
| 20030153806 | Miller | Aug 2003 | A1 |
| 20030153983 | Miller et al. | Aug 2003 | A1 |
| 20030153985 | Lee | Aug 2003 | A1 |
| 20030157142 | Nagel et al. | Aug 2003 | A1 |
| 20030171646 | Pratt et al. | Sep 2003 | A1 |
| 20030215519 | Schwartz et al. | Nov 2003 | A1 |
| 20040014936 | Grunze et al. | Jan 2004 | A1 |
| 20040020497 | Knudson et al. | Feb 2004 | A1 |
| 20040028676 | Klein et al. | Feb 2004 | A1 |
| 20040047892 | Desrosiers et al. | Mar 2004 | A1 |
| 20040091425 | Boschetti | May 2004 | A1 |
| 20040096514 | Vogel et al. | May 2004 | A1 |
| 20040096969 | Grunze | May 2004 | A1 |
| 20040117033 | Frondoza et al. | Jun 2004 | A1 |
| 20040142465 | Radice et al. | Jul 2004 | A1 |
| 20040185021 | Hubbard | Sep 2004 | A1 |
| 20040187878 | Knudson et al. | Sep 2004 | A1 |
| 20040210230 | Furlow | Oct 2004 | A1 |
| 20040241203 | Shakesheff et al. | Dec 2004 | A1 |
| 20050025708 | Vogel et al. | Feb 2005 | A1 |
| 20050037047 | Song | Feb 2005 | A1 |
| 20050136093 | Denk | Jun 2005 | A1 |
| 20050165203 | Kohn et al. | Jul 2005 | A1 |
| 20050208095 | Hunter et al. | Sep 2005 | A1 |
| 20050209629 | Kerr et al. | Sep 2005 | A1 |
| 20050234210 | Andrianov et al. | Oct 2005 | A1 |
| 20060008529 | Meyerhoff et al. | Jan 2006 | A1 |
| 20060067883 | Krom et al. | Mar 2006 | A1 |
| 20060088476 | Harder et al. | Apr 2006 | A1 |
| 20060147895 | Purdum | Jul 2006 | A1 |
| 20060201673 | Welton et al. | Sep 2006 | A1 |
| 20060240064 | Hunter et al. | Oct 2006 | A9 |
| 20060246109 | Hossainy et al. | Nov 2006 | A1 |
| 20060251582 | Reb | Nov 2006 | A1 |
| 20060251697 | Li | Nov 2006 | A1 |
| 20070003503 | Sabetsky | Jan 2007 | A1 |
| 20070003584 | Anderson | Jan 2007 | A1 |
| 20070077544 | Lemperle et al. | Apr 2007 | A1 |
| 20070100449 | O'Neil et al. | May 2007 | A1 |
| 20070191964 | Preissman | Aug 2007 | A1 |
| 20070240725 | McKay | Oct 2007 | A1 |
| 20070292429 | Brady et al. | Dec 2007 | A1 |
| 20080003256 | Martens et al. | Jan 2008 | A1 |
| 20080015498 | Lesh | Jan 2008 | A1 |
| 20080058954 | Trieu | Mar 2008 | A1 |
| 20080095816 | Gordy et al. | Apr 2008 | A1 |
| 20080102029 | Fritz et al. | May 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| 1252253 | Apr 1989 | CA |
| 19613048 | Oct 1996 | DE |
| 19613048 | Oct 1996 | DE |
| 19744135 | Mar 1999 | DE |
| 10019982 | Oct 2001 | DE |
| 10100961 | Aug 2002 | DE |
| 0150699 | Aug 1985 | EP |
| 0286709 | Oct 1988 | EP |
| 0706376 | Jun 1997 | EP |
| 0804909 | Nov 1997 | EP |
| 0970711 | Jan 2000 | EP |
| 1112094 | Jul 2001 | EP |
| 1179353 | Feb 2002 | EP |
| 1337285 | Aug 2003 | EP |
| 1426075 | Jun 2004 | EP |
| 0970711 | Oct 2004 | EP |
| 1488817 | Dec 2004 | EP |
| 58079915 | May 1983 | JP |
| 62086024 | Apr 1987 | JP |
| 4337328 | Nov 1992 | JP |
| 7082279 | Mar 1995 | JP |
| WO 8809664 | Dec 1988 | WO |
| WO 9321858 | Nov 1993 | WO |
| WO 9502628 | Jan 1995 | WO |
| WO 9528150 | Oct 1995 | WO |
| WO 9528966 | Nov 1995 | WO |
| WO 9600103 | Jan 1996 | WO |
| WO 9604015 | Feb 1996 | WO |
| WO 9625176 | Aug 1996 | WO |
| WO 9625897 | Aug 1996 | WO |
| WO 9629059 | Sep 1996 | WO |
| WO 9800531 | Jan 1998 | WO |
| WO 9831734 | Jul 1998 | WO |
| WO 9843618 | Oct 1998 | WO |
| WO 9852605 | Nov 1998 | WO |
| WO 9856312 | Dec 1998 | WO |
| WO 9909088 | Feb 1999 | WO |
| WO 9916416 | Apr 1999 | WO |
| WO 9916477 | Apr 1999 | WO |
| WO 9916477 | Apr 1999 | WO |
| WO 9942147 | Aug 1999 | WO |
| WO 9952356 | Oct 1999 | WO |
| WO 0032238 | Jun 2000 | WO |
| WO 0056254 | Sep 2000 | WO |
| WO 0061204 | Oct 2000 | WO |
| WO 0136008 | May 2001 | WO |
| WO 0136008 | May 2001 | WO |
| WO 0145763 | Jun 2001 | WO |
| WO 0149340 | Jul 2001 | WO |
| WO 0170296 | Sep 2001 | WO |
| WO 0172281 | Oct 2001 | WO |
| WO 0180919 | Nov 2001 | WO |
| WO 0180919 | Nov 2001 | WO |
| WO 0180919 | Nov 2001 | WO |
| WO 0187368 | Nov 2001 | WO |
| WO 0187372 | Nov 2001 | WO |
| WO 0213882 | Feb 2002 | WO |
| WO 0224247 | Mar 2002 | WO |
| WO 02064666 | Aug 2002 | WO |
| WO 02064666 | Aug 2002 | WO |
| WO 02077073 | Oct 2002 | WO |
| WO 03015719 | Feb 2003 | WO |
| WO 2004004795 | Jan 2004 | WO |
| WO 2004011055 | Feb 2004 | WO |
| WO 2004048432 | Jun 2004 | WO |
| WO 2004060283 | Jul 2004 | WO |
| WO 2006046155 | May 2006 | WO |
| WO 2007056316 | May 2007 | WO |
| Entry |
|---|
| Allcock, Harry R., “Poly(organophosphazenes-Unusual New High Polymers,” Angew. Chem. Int. Ed. Engl. 16, 147-156 (1977). |
| Caliceti, Paolo, et al., “Polyphosphazene microspheres for insulin delivery,” International Journal of Pharmaceutics, 211 (2000) 57-65. |
| International Search Report and Written Opinion (PCT/US2007/082659, International Searching Authority, 2007. |
| Kumbar, Sangamesh G., et al., In Vitro and In Vivo Characterization of Biodegradable Poly(organophosphazenes) for Biomedical Applications, Journal of Inorganic and Organometallic Polymers and Materials, vol. 16, No. 4, Dec. 2006, pp. 365-385. |
| Acta Polymerica 30 (1979), pp. 245-248. |
| Acta Polymerica 36 (1985), pp. 627-631. |
| Acta Polymerica 37 (1986) No. 4:203-208. |
| Allcock, Harry, R., et al., “Antibacterial activity and mutagenicity studies of water-soluble phosphazene high polymers,” Biomaterials, vol. 13. No. 2, pp. 857-862 (1992), Butterworth-Heinemann Ltd., USA. |
| Allcock, H., “Phosphazene high polymers with bioactive substitutent groups: prospective anesthetic aminophosphazenes,” Macromolecules, 15(3):689-693 (1982). |
| Ambrosio, et al., “Novel Polyphosphazene-Hydroxyapatite Composites as Biomaterials,” IEE Engineering in Medicine and Biology Magazine, Sep./Oct. 2003, pp. 18-26. |
| Barrett, Eric W., “Patterning Poly(organophosphazenes) for Selective Cell Adhesion Applications,” Biomacromolecules, (2005), 6, 1689-1697. |
| Barrett, Eric W., “Polyphosphazenes for Biomedical Devices and Other Applications,” Ph.D. Thesis in Chemistry, Pennsylvania State University, Dec. 2005. |
| Chaikof, Elliott L., “The Development Prosthetic Heart Valves—Lessons in Form and Function,” Oct. 4, 2007, vol. 357:1368-1371, No. 14. |
| Champion, J., et al., “Particle shape: A new design parameter for micro- and nanoscale drug delivery carriers,” Journal of Controlled Release, 121 (2007) 3-9. |
| Chaubal, M., et al., “Polyphosphates and other phosphorus-containing polymers for drug delivery applications,” Critical Reviews™ in Therapeutic Drug Carrier Systems, 20(4):295-315 (2003). |
| Cohen, Smadar, et al., “Design of Synthetic Polymeric Structurs for Cell Transplantation and Tissue Engineering,” Clinical Materials, vol. 13, 3-10 (1993), Elsevier Science Publishers Ltd., England. |
| Contreras, Miguel Angel, et al., “Temperature coefficients of peptides dissolved in hexafluoroisopropanol monitor distortions of helices,” Letters in Peptide Science, 4 (1979) 29-39. |
| Cui, et al., “Preparation of Controlled Releasing Acrylic Polymer Microspheres of Acebutolol Hydrochloride and Those Powder Coated Microspheres with Sodium Alginate in a Polymeric Spherical Crystallization System,” Che. Phar. Bull., (1990), vol. 44, No. 4, pp. 837-842. |
| De Jaeger, Roger, et al., “Poly(organophosphazene)s and Related Compounds: Synthesis, Properties and Applications,” Prog. Polym. Sci., vol. 23, 179-276 (1998), Pergamon Press, Great Britain. |
| De Scheerder, Ivan K., et al., “Angiopeptin Loaded Stents Inhibit the Neointimal Reaction Induced by Polymer Coated Stents Implanted in Porcine Coronary Arteries,” Abstract 772-6, pp. 286A, JACC (Feb. 1995). (Abstract). |
| El-Amin, et al., “The Biocompatibility of Biodegradable Glycine Containing Polyphosphazenes: A Comparative Study in Bone,” Journal of Inorganic and Organometallic Polymers and Materials, 2006, vol. 16, No. 4, pp. 387-396. |
| Gast, Klaus, et al., “Fluoroalcohol-induced structural changes of proetins: some aspects of cosolvent-protein interactins,” Eur Biophys J (2001) 20: 273-283. |
| Goedemoed, J., et al., “Development of implantable antitumor devices based on polyphosphazenes,” Die Makromolekulare Chemie, 19:341-365 (1988). |
| Grunze, Michael, et al., 32P-labeled polyphosphazenes, 1999, Chemical Abstracts, vol. 130, No. 20: 272061. |
| Guigley, Kevin S., “Hydrogen Bonded Polymer Blends,” Ph.D. Thesis in Materials Science and Engineering, Pennsylvania State Univerfsity, Dec. 2001. |
| Hansen, Charles M., “Hansen Solubility Parameter—A User's Handbook,” 2000 by CRC Press LLC. |
| Henry, R., et al., “Topical lidocaine-prilocaine spray for the treatment of premature ejaculation,” International Journal of Impotence Research, 15(4):277-281 (2003). |
| Honarkar, Hengameh, et al., “Applications of inorganic Polymeric Materials, III: Polyphosphazenes,” Monatshefte fur Chemie 138, 923-933 (2007). |
| Hori, Yoshio, et al., “Functional Analysis of the Tissue-Engineered Stomach Wall,” Artificial Organs, 2002, 26 (10):868-893, Blackwell Publishing, Inc., International Society for Artificial Organs. |
| Huang, Yangmin, et al., “Long-term biocompatability evaluation of a novel polymer-coated sent in a porcine coronary stent model,” Therapy and prevention, 2003, Coronary Artery Disease, vol. 14, No. 5, 401-408. |
| Ibim, Sobrasua M., et al., “Controlled Macromolecule Release from Poly(phosphazene) Matrices,” Journal of Controlled Release, vol. 40, 31-39 (Jun. 1996), Elsevier Science B.V. |
| International Search Report and Written Opinion (PCT/US2007/082426), International Searching Authority, 2007. |
| International Search Report and Written Opinion (PCT/US2007/082430), International Searching Authority, 2007. |
| International Search Report and Written Opinion (PCT/US2007/082651), International Searching Authority, 2007. |
| International Search Report and Written Opinion (PCT/US2007/082672), International Searching Authority, 2007. |
| International Search Report and Written Opinion (PCT/US2007/083199), International Searching Authority, 2007. |
| International Search Report and Written Opinion (PCT/US2007/083209), International Searching Authority, 2007. |
| International Search Report and Written Opinion (PCT/US2007/083043), International Searching Authority, 2007. |
| International Search Report and Written Opinion (PCT/US2007/083216), International Searching Authority, 2007. |
| Jayakrishnan, et al., “Hydrogel microspheres from crosslinked poly(methyl methacrylate): synthesis and biocompatibility studies,” Bull. Mater. Sci., Mar. 1989, vol. 12, No. 1, pp. 17-25. |
| Kajiwara, M., “The Study of the Cultivaton of Chinese Hamster Ovary and Bows Cell Lines,” Phosphorus, Sulfur, and Silicon, vol. 76, pp. 163-166 (1993), Gordon and Breach Science Publishes S.A., USA. |
| Kingshott, P., “Surfaces that Resist Bioadhesion,” Current Opinion in Solid State and Materials Science, vol. 4, 403-412 (1999), Pergamon. |
| Kumar, Yogesh, et al., “Influence of Fluoro. Chloro and Alkyl Alcohols on the Folding Pathway of Human Serum Alubmin,” J. Biochem, (2005), 138, 335-341. |
| Kumar, Yogesh, et al., “Molten-globule like partially folded states of human serum albumin induced by fluoro and alkyl alcohols at low pH,” Archives of Biochemistry and Biophysics, 426 (2004) 3-10. |
| Laurencin, Cato T., et al., “use of polyphosphazenes for skeletal tissue regeneratin,” J. Biomedical Maerials Research, vol. 27, No. 7, pp. 963-973 (1993), John Wiley & Sons, Inc., USA. |
| Laurencin, C. et al., “Controlled release using a new bioerodible polyphosphazene matrix system,” Journal of Biomedical Materials Research, 21:1231-1246 (1987). |
| Lemmouchi, Y., et al., “Biodegradable Polyphosphazenes for Drug Delivery,” Macromolecular Symposia, vol. 123, 103-112 (Sep. 1997) Wiley VCH, Weinheim, Germany. |
| Lopez, Gabriel P., et al., “Glow Discharge Plasma Deposition of Tetraethylene Glycol Dimethyl Ether for Fouling-Resistant Biomaterial Surfaces,” J. of Biomedical Materials Research, vol. 26, 415-439 (1992), John Wiley & Sons, Inc., USA. |
| Macromolecules 1987, vol. 20, pp. 782-789. |
| Maher, Andrew Elessar, “Synthesis and Characterization of Mixed-Substitutent Poly(Organophosphazenes),” Ph.D. Thesis in Chemistry, Pennsylvania State University, May 2004. |
| “Making Better Magnetic Nanoparticles,” Physorg.com, Science:Physics: Tech:nano:news; Source: National Cancer Institute, Dec. 18, 2006. |
| Mark, James E., et al., “Polyphosphazenes”, Inorganic Polymers, 1992, pp. 61-139, XP000866367, pp. 95-117. |
| McCaffrey, R.R. et al., “Synthesis, Casting, and Diffusion Testing of Poly[bis(tri-fluoroethoxy)phosphazene] Membranes,” J. of Membrane Science, vol. 28, 47-67 (1986), Elsevier Science Publishers B.V., Netherlands. |
| Mrowietz, C., et al., “Haemocompatibility of polymer-coatd stainless steel stents as compared to uncoated stents,” Clinical Hemorheology and Microcirculation, 32 (2005) 89-103. |
| Nielsen, Gunmar D., et al., “Sensory irritation mechanisms investigated from model compounds: trifluoroethanol, hexafluoroisopropanol and methyl hexafluoroisopropyl ether,” 1996, Arch Toxicol, 70:319-328. |
| Phadke, et al. ,“Embolization of Cranial/Spinal Tumors and Vascular Malformations with Hydrogel microspheres,” Acta Radiologica, 2002, vol. 43, pp. 15-20. |
| Ph. Potin & R. DeJaeger, “Review: Polyphosphazenes: Synthesis, Structures, Properties, Applications,” European Polymer Journal, vol. 27, 341-348 (1991), Pergamon Press, Great Britain. |
| Rao, et al., “Hydrolysed Microspheres From Cross-Linked Polymethyl Methacrylate (Hydrogel)”, J. Neuroradiol, 1991, vol. 18, pp. 61-69. |
| Reichert, W. M., et al., “Polyphosphazenes: Effect of molecular motions on thrombogenesis,” Journal of Biomedical Materials Rsearch, (1982), vol. 16, 301-312. |
| Richter, Goetz M., et al., “A New Polymer Concept for Coating of Vascular Stents using PTFEP (poly(bis(trifluoroethoxy)phosphazene) to Reduce Thrombogenicity and Late In-Stent Stenosis,” Investigative Radiology, Apr. 2005, vol. 40, No. 4, 210-218. |
| Roccatano, Danilo, et al., “Effect of hexafluoroisopropanol alcohol on the structure of melittin: A molecular dynamics simulation study,” Protein Science, 2005, 14:2582-2589. |
| Rothemund, Sven, et al., “Temperature coefficients of amide proton NMR resonance frequencies in trifluoroethanol: A monitor of intramolecular hydrogen bonds in helical peptides?” Journal of Biomecular NMR, 8 (1996) 93-97. |
| Rupp, Frank, et al., “Initials Biofilm Formations by Dynamic Protein Interactions at Surface-Modified Titanium Implants,” BIOmaterialien, Apr. 2003. |
| Steely, Lee Brent, “Hydrophobic and Hydrophilic Conrol in Polyphosphazene Materials,” Ph.D. Thesis in Chemistry, Pennsylvania State University, Aug. 2007. |
| Thanoo, et al., “Preparation of Hydrogel Beads from Crosslinked Poly(Methyl Methacrylate) Microspheres by Alkaline Hydrolysis,” J. Appl. P. Sci., vol. 39, pp. 1153-1161 (1990) (abstract only). |
| Veronese, Francesco M., et al., “Polyphosphazene Membranes and Microspheres in Periodontal Diseases and Implant Surgery,” Biomaterials, vol. 20, 91-98 (1999), Elsevier, USA. |
| Vinogradova, S.V., et al., “Open-chain Poly(organophosphazenes). Synthesis and Properties,” Russian Chemical Reviews, vol. 67, 515-534 (1998), Russian Academy of Sciences and Turpion Ltd. |
| Waksman, R., “Vasvular Brachytherapy: Applications in the Era of Drug-Eluting Stents,” reviews in Cardiovascular Medicine, vol. 3, S23-S30 (2002), Medreviews, LLC, USA. |
| Welle, A., et al., “Plasma Protein Adsorption and Platelet Adhesion on Poly[bis(trifluoroethoxy)phosphazene] and reference material surfaces,” appeared in J. Colloid Intef. Sci., 197, 263-274, (1998). |
| Welle, A., et al., “Polyphosphazenes as antithrombotic coatings for prostetic heart elves,” Presented at 19th Annual Meeting of the Adhesion Society, Myrtle Beach, SC, 4 pages (Feb. 1996). |
| Welle, Alexander, et al., “Blood Compatibility of Poly[bis(trifluoroethoxy)phosphazene],” Institute of Applied Physical Chemistry, JAMP, vol. 4, 6-10, (2000), University of Heidelberg, Germany. |
| Welle, Alexander, “Competitive plasma protein adsorption on modified polymer surfaces monitored by quartz crystal microbalance technique,” J. Biomater. Sci. Polymer Edn. (2004) vol. 15, No. 3, pp. 357-370. |
| Welna, Daniel Thomas, “Design, Synthesis, and Characterization of Polymeric Materials for uses in Energy Storage Applications,” Ph.D. Thesis in Chemistry, Pennsylvania State University, Aug. 2006. |
| Yao, Shenggen, et al., “Peptide self-association in aqueous trifluoroethanol monitored by pulsed field gradient NMR diffusion measurements,” Journal of Biomolecular NMR, 16:109-111, 2000. |
| Zeifang, Felix, et al., “Improved osseointegration of PTFEP-coated titanium implants,” Med Sci Monit, 2008; 14(2): BR35-40, PMID: 18227757. |
| Zeifang, Felix, et al., “Method of non-destructive mechanical testing of new surface coatings for prostheses,” Biomed Tech 2006; 51:3-7. |
| Number | Date | Country | |
|---|---|---|---|
| 20090117637 A1 | May 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10250985 | US | |
| Child | 12237928 | US |
