Claims
- 1. A composite article comprising in sequence:
- (a) a polymeric fibrous support having a large surface area, which surface has been subjected to a surface plasma treatment carried out at a frequency of 10 to 125 kiloherz with a power density in the range of 0.05 to 2.25 w/cm.sup.2 generated between two electrodes in a gas at a pressure in the range of 10 mtorr to 10 torr to provide a polar surface having binding sites thereon,
- (b) a layer of a protein immobilizer compound comprising a polymer or a silane-functional compound adhering to the resulting treated surface and capable of immobilizing enzymes, and
- (c) an enzyme bound to said layer of protein immobilzer compound.
- 2. The article according to claim 1 wherein said plasma treatment utilizes a gas selected from the group consisting of air, oxygen, carbon dioxide, argon, helium, nitrous oxide, or water vapor.
- 3. The article according to claim 1 wherein said gas is air or carbon dioxide.
- 4. The article according to claim 1 wherein said support is woven or nonwoven.
- 5. The article according to claim 1 wherein said support is polyalkylene, polyvinyl chloride, polyamide, polyvinyl alcohol, polystyrene, polyacrylsulfone, polyester, polycarbonate, polyacrylate, cellulosic, polyurethane, or combinations thereof.
- 6. The article according to claim 1 wherein said polymer is a beta-hydroxyalkyleneamine-containing polymer, and the silane-functional compound is a silane-treated polycarbodiimide polymer.
- 7. The article according to claim 6 wherein said polymer is an amine adduct of epoxidized poly-cis-1,4-butadiene, epoxidized styrene/cis-1,4-butadiene, or polyglycidyl methacrylate.
- 8. The article according to claim 7 wherein said amine is dimethylamine, diethylamine, morpholine, piperidine, or n-propylamine.
- 9. The article according to claim 1 wherein said enzyme is urease, glucose oxidase, invertase, peroxidase, catalase, papain, lipase, cellulase, dextranase, amylase, ribonuclease, carboxypeptidase or urokinase.
FIELD OF THE INVENTION
This is a continuation of application Ser. No. 06/796,274 filed Nov. 8, 1985 now U.S. Pat. No. 4,757,014.
This invention relates to a composite article comprising an immobilized biologically active protein. In another aspect, a process for preparing the composite article of the invention is disclosed. The article can be used in a method for disinfecting medical devices, particularly contact lenses.
Soft contact lenses, such as those made from plastic gel materials, e.g., hydroxyethyl methacrylate (HEMA) or its analogues and ethylene glycol dimethacrylate (EGMA) of its analogues, are replacing traditional hard contact lenses as the lenses of choice for many people. Soft lenses are more comfortable to wear than the hard lenses, but they pose a more complex problem than the hard lenses when it comes to care and maintenance. Hard lenses may be cleaned and disinfected relatively easily. Since they do not absorb appreciable amounts of water and aqueous solutions, the use of somewhat harsh cleaning and disinfecting agents is not generally a problem.
Soft lenses, on the other hand, require greater care in cleansing and storage. The solutions useful with hard lenses often are not compatible with soft lenses because the soft lenses tend to absorb or concentrate certain constituents of the formulation, which could result in damage to the lens or harm to the eye of the user.
Similarly, soft lenses are more vulnerable to microbial contamination than are hard lenses. the nutritive effect of body fluids, and the protective effect of nicks or imperfections in soft lenses, can serve to augment the growth of microbes.
While it is relatively easy to find antimicrobial agents active against such microbial contaminants, it is more difficult to find an antimicrobial agent that is compatible with soft contact lenses, and more difficult yet to find one that is non-irritating and safe for contact with the human eye.
Antimicrobial agents which are suitable for external contact or even for injection or ingestion are often unsuitable for use in eye care due to the particularly sensitive nature of the tissues in the eye. For example, they might be unsuitable because of direct toxicity to the eye, poor solubility in aqueous vehicles, eye irritation or ocular allergenic effects, absorption or binding by the contact lens, or chemical interaction with the contact lens or even its plastic lens case.
An antimicrobial agent useful for ocular applications must not contribute to any of the above problems. In particular, it must satisfy two basic requirements, i.e. that it be non-irritating to the eye, and that it be effective against a wide variety of microorganisms.
Hydrogen peroxide is a very effective antimicrobial agent which is currently used to disinfect contact lenses, including soft contact lenses. Although it is potentially irritating to the eye if significant residues are contained on or in the contact lens, it is known that hydrogen peroxide can be removed by soaking a disinfected lens in a solution containing a catalyst such as platinum oxide which catalyzes the decomposition of hydrogen peroxide.
Solutions of the enzyme catalase have also been added to decompose hydrogen peroxide in solutions previously used to sterilize contact lenses. See, for example, European Patent application 82710055.3. However, if introduced into a solution with a lens, catalase can bind to the lens, compounding the familiar protein deposit problem associated with the use of contact lenses.
It is known in the art that certain proteins can be immobilized on specific supports. U.S. Pat. No. 4,098,645 describes the immobilization of enzymes on isocyanate end-capped polyurethane polymer foams, and catalase is one of a long list of enzymes listed and claimed.
U.S. Pat. No. 3,282,702 describes certain classes of polymeric carriers which bind catalase for the purpose of providing articles for removing hydrogen peroxide from potable liquids.
U.S. Pat. No. 4,210,722 describes a method of immobilizing a protein such as an enzyme on a polar support in a variety of configurations which can be glass, ceramic, inorganic oxide, etc. comprising applying a layer of a polymer having repeatig units containing a beta-hydroxyalkyleneamine moiety such as the dimethylamine adduct of epoxidized polybutadiene to a polar support and contacting the treated support with an aqueous solution of the protein. One of the enzymes exemplified in this patent is catalase.
Briefly, the present invention provides a composite article comprising in sequence a fibrous support which has been subjected to a surface modification treatment to provide binding sites thereon, a layer of protein immobilizer, and a biologically active protein.
In another aspect, a process for preparing composite articles containing immobilized protein is disclosed.
Fibrous supports, such as woven and particularly nonwoven webs, because of their ease of handling and high surface area, provide desirable constructions upon which proteins such as enzymes can be immobilized. It has been found, however, that some of the typical polymers used to make woven and nonwoven webs, such as polyalkylenes, do not irreversibly absorb or bind the protein immobilizers known to the art. Immobilized proteins such as enzymes can retain a substantial portion of their biological activity even though bound to a support.
Surprisingly, it has been found that certain polymers, including polyalkylenes, commonly used to make nonwoven webs can be used as supports for protein immobilization if their surface is first subjected to a modification treatment capable of providing binding sites for a protein immobilizer compound. It has not previously been known to treat woven and nonwoven webs for the purpose of providing binding sites for chemical additives.
It has not previously been known that it is possible to achieve disinfection with hydrogen peroxide while simultaneously decomposiing excess hydrogen peroxide by the use of the protein catalase immobilzed upon a support. In particular, the use of catalase, immobilized upon a woven or nonwoven fibrous support coated with a layer of inorganic oxide or subjected to a plasma treatment, to decompose hydrogen peroxide has not been known.
Hydrogen peroxide systems, which have been used to disinfect contact lenses, may be classified by the number of containers used during the disinfection process and by the number of steps required to complete the disinfection process.
A two-container, two-step method involves separate, noncompeting reactions. In the first step lenses are put into a container containing an amount of hydrogen peroxide sufficient for disinfecting the lenses in a short period of time (about 10 minutes). In the second step, as is known in the art, the lenses are then transferred to a second container which contains a saline solution and a disc of platinum. The platinum disc catalytically converts the hydrogen peroxide into molecular oxygen and water. The lenses are soaked in the second container for four or more hours to remove the residual hydrogen peroxide from the lenses. Other systems which have been used to remove the hydrogen peroxide from the lenses can include either the use of a solution of sodium bicarbonate or the enzyme catalase in solution. These systems may use one or two containers but always require two steps: first a soak in hydrogen peroxide and second a neutralization step.
The two-step, two-container system is bulky, cumbersome and requires relatively large volumes of solutions. Two-step, one-container systems are also bulky, cumbersome and require more than one solution. A problem arises when the wearer forgets the second step and does not neutralize the hydrogen peroxide in the lenses. The wearer then has lenses which are contaminated with hydrogen peroxide and are not suitable for use. It is, therefore, desirable to provide a system which uses only one container and one step to achieve the disinfection of the lenses and the neutralization of the hydrogen peroxide.
When a one-step system is used to disinfect contact lenses there are two competing reactions which must be controlled to achieve disinfection as well as neutralization. One reaction is the killing of the infectious organisms on the lenses by the hydrogen peroxide. The concentration of the hydrogen peroxide must remain at a high enough level for a period of time long enough to achieve disinfection. The second reaction is the conversion of residual hydrogen peroxide into water and molecular oxygen or other compounds. The conversion reaction must be slow enough to allow killing of the microorganisms but fast enough to neutralize substantially all of the hydrogen peroxide in a period of time suitable for having the lenses ready for use (usually four to six hours).
The present invention permits the use of a onecontainer, one-step system by controlling the amount of enzyme present. The amount of immobilized enzyme put into the container can be controlled by selecting the appropriate amount of composite article. A low amount of enzyme will cause a slow neutralization of hydrogen peroxide which will allow the disinfection to take place. If, on the other hand, a fast system for hydrogen peroxide disinfection is desired, a two-step system would be preferable: a large concentration of enzyme can be put into the container after the 10-minute disinfecting soak and the large amount of enzyme will neutralize the hydrogen peroxide very rapidly, reducing the total required time for disinfection. A very fast system is highly desirable for patients wearing extended wear lenses who do not wish to leave their lenses out of their eyes for the four- to six-hour period required by products currently available.
The activity of the enzyme in neutralizing hydrogen peroxide can also be attentuated by use of controlled release technology, as is known in the art. For example, the composite article of the invention may be coated with a slowly erodable polymer such as a cellulose derivative, poly(N-vinyl pyrrolidone) or poly(vinyl alcohol). The erodable polymer coating on the surface prevents the enzyme from neutralizing the hydrogen peroxide and slowly dissolves in the hydrogen peroxide solution. When the polymeric coating has dissolved into the solution, the enzyme neutralizes the hydrogen peroxide at a rate proportional to the amount of active enzyme present.
The medical devices which can be disinfected in conjunction with the composite article of the invention can be any article which is used in or applied to the human body and which must be free of significant amounts of hydrogen peroxide after disinfection. Such articles include devices used in the eye which may require regular disinfection such as contact lenses. Other articles suitable for disinfection include medical and dental instruments, surgical staples, and implants of various types. A method for disinfecting medical devices using the article of the invention is disclosed in assignee's copending patent application U.S. Ser. No. 06/796272, filed the same date as this application.
As used in this application:
"woven fibrous web" means a sheet or pad of interlaced strands of yarn;
"nonwoven fibrous web" means a sheet or pad of a random network of fibers;
"ceramic" means any inorganic nonmetallic material (includes metal and nonmetallic oxides) which requires the application of high temperatures at some stage in its manufacture but is not derived from a melt;
"ceramic-precursor" means a material capable of being converted to a ceramic by application of high temperature;
"sol" means a colloidal dispersion of a finely divided solid phase in a liquid medium;
"polar layer" means a layer the surface of which is wettable by water;
"continuous" means a layer with virtually no discontinuities or gaps therein;
"gelled network" means an aggregation of colloidal particles linked together to form a porous three-dimensional network;
"particle" means spherical, non-spherical, and fibrillar particulate arrangements;
"primary particle size" means the average size of unagglomerated single particles of inorganic metal oxide;
"porous" means the presence of voids created by the packing of particles; the dried product preferably has an open porosity of between 25 and 70 percent;
"monolayer" means a thin layer approximately 10 to 250 angstroms thick, with the preferred thickness being in the range of 10 to 100 angstroms;
"mat" means unfused fiber;
"thermally bonded" means a mat of fibers that has been fused by heat at junction points (e.g., passed through calendering rolls at 232.degree. C. (450.degree. F.)); and
"embossing" means a mat of fibers thermally fused by imprinting a pattern on the mat.
US Referenced Citations (16)
Foreign Referenced Citations (5)
| Number |
Date |
Country |
| 6065286 |
Jul 1986 |
AUX |
| 0082798 |
Jun 1983 |
EPX |
| 0155505 |
Sep 1985 |
EPX |
| 0209071 |
Jan 1987 |
EPX |
| 8607264 |
Dec 1986 |
WOX |
Continuations (1)
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Number |
Date |
Country |
| Parent |
796274 |
Nov 1985 |
|
Patent Grant
4855234
