Patent Application
20240033228
The present invention is part of the technical sector of systems for the administration of substances inside the human body and has particularly as its object a system of nanoparticles for the administration and delivery of at least one active principle, generally known as DDS or drug delivery systems. Specifically, the invention relates to the use of a carrier which carries at least one active principle such as for example a substance having an antimicrobial and/or antibacterial and/or mucolytic nature for the eradication of biofilms, for example of bacterial origin.
The methods for administering pharmaceutically and pharmacologically active ingredients show a wide variability in terms of technology and application, depending on some chemical and physical characteristics of the latter, such as solubility and permeability.
It is known that the most common methods of drug administration are by mouth or by injection. Lipophilic molecules represent a relatively difficult challenge in achieving systemic circulation. It is also known that these molecules belong, according to the Biopharmaceutical Classification System (BCS), to the second class (II), having low solubility and. consequently low bioavailability (Advance Pharmaceutical Journal 2017; 2(6): 204-209).
In another context of the state of the art, it is known that microorganisms, primarily bacteria but also fungi, have a form of innate self-defense due to the formation of niches, called biofilms, which represent the most common condition of life, compared to the free or planktonic form (Pharmaceutics 2018, 10, 279).
The aforementioned biofilms are in fact consortia of microorganisms generally adhering biotic or abiotic surface, surrounded by a mucilaginous matrix that they self-produce. It is known that in this state, biofilms are more resistant to external attacks than cells in planktonic form.
Firstly, this is due to the presence of the matrix, an aqueous gel of exopolysaccharides, proteins and extracellular DNA that hinders the diffusion of molecules inside, secondly to the release of enzymes that degrade antibiotic molecules or to efflux pumps that extrude substances.
Furthermore, bacteria can live in a quiescent form such as persisters or small colony variants, with slowed metabolism.
From this it follows that conventional methods of treating biofilm-associated infections involve intensive administration of antibiotics, therefore high doses and for prolonged times. This generates numerous adverse effects, including emergence of antibiotic resistance and superbugs, adverse effects on the microbiome, or hypersensitivity.
These issues have led research to focus on alternative therapies to antibiotics, including bacteriophages, antimicrobial peptides, specific molecules that target structures within biofilms or that interfere with quorum sensing, i.e., the process that regulates communication between cells and which appears to be fundamental for the formation of the aforementioned structures such as biofilms.
In this context of innovation also nanotechnologies are inserted, structures of which at least one of the dimensions is of the order of nanometres and which, precisely because of the aforementioned dimensions, have peculiar characteristics different from the bulk counterpart of the same materials that constitute them.
Some nanoparticles (NPs) are studied precisely to have antibacterial characteristics, interacting with the bacterial membrane or wall, or generating reactive oxygen species or other nanostructures are able to deliver antibacterial drugs to the site of infection.
In this context, among the inorganic materials (Pharmaceutics 2018, 10, 279), mesoporous silica nanoparticles (MSN) emerge, known for their stability, high surface area and high pore volume, which give them high loading capacity of molecules of different types.
For this reason, the most recent studies have focused on the search for carriers that can overcome the aforementioned limit in the bioavailability of the so-called pharmaceutically active ingredients (API—Active Pharmaceutical Ingredients) (Nature Materials 2013 12: 991-1003; Expert Opinion on Drug Delivery 2016, 13(1): 93-108).
In this sense, the vehicle and drug delivery systems (DDS—Drug Delivery Systems) with a nanometric structure have aroused great interest as they provide large surface areas available for the adsorption of APIs.
Furthermore, they are versatile systems that allow multiple surface modifications to allow a more effective control of the release conditions for the molecules of interest.
Among the various solutions proposed, mesoporous inorganic materials have aroused particular interest, which have proved to be effective as API carriers.
Recent studies have focused in particular on the composition of mesoporous materials and on the main advantages deriving from mesoporous carriers based on the variation of structural parameters such as size, surface area, pore volume and pore distribution.
In particular, among these materials great attention has been paid to the use of mesoporous silica nanoparticles such as DDS, thanks to the ease of modifying the properties of these nanoparticles.
In fact, thanks to a surface area usually up to 1000 m2/g and a pore volume between 0.5-1.0 cm3/g, these materials are able to accommodate molecules of different sizes, shapes and steric hindrance (Expert Opinion on Drug Delivery 2016, 13(1): 93-108; Pharmaceutics 2020, 12(5): 432; Molecules 2018, 23(1): 47).
Furthermore, the chemical-physical properties of these carriers, such as the surface charge or the presence of specific functional groups, can be suitably modified to specifically charge molecules with peculiar characteristics.
Last but not least, the possibility of functionalising both the internaland external surface of the nanoparticles with organic fractions, produces extremely versatile materials for further investigations, also in terms of the ability to interact with different biological effectors.
For example, surfaces can be rendered hydrophobic or hydrophilic, while the presence of organic residues could increase affinity for a specific molecular target or affect the bioavailability or biodistribution of nanoparticles.
Furthermore, different functionalizations could coexist on the same surface, expanding the field of possible applications.
In particular, it is known how titanium oxide or silicon dioxide nanoparticles could allow the prolonged and controlled release of drugs at the site of interest while preserving the stability of the charged molecules and improving their bioavailability for a prolonged time (Nanomed Nanotechnol 2018,3 (2):000136.; Acta Biomaterialia 2015 13: 354-363). Further advantages could be better solubility and permeability of biological membranes, better temporal stability and better therapeutic performance of drugs.
While mesoporous silica NPs such as DDS have been a highly studied research field due to their ease of modification of the properties of these nanoparticles (Pharmaceutics 2020, 12(5): 432), mesoporous zirconia (ZrCb) nanoparticles (MZN) have been recently introduced and have been little studied (J. Mater. Chem.B, 2015, 3, 7300; WO2016120795; J. Drag Deliv. So. Technol, 2021, 61, 102189).
As is known, zirconium and its oxides are biocompatible and non-toxic materials and, for this reason, they are used in many applications, for example in orthopaedics and dentistry. Regarding zirconia nanoparticles, the toxicological profile is first strongly dependent on their size. For example, Yang et al., described intravenous administration of hollow ZrCb nanoparticles greater than 150 nm in diameter, which did not show toxicity up to 500 mg/kg in mice (International Journal of Nanomedicine 2019, 14: 5175-5186).
It follows that MZN particles could show important advantages for biomedical applications in vivo and for API loading processes.
From different references known to the literature, zirconium-based materials show a remarkable affinity for phosphate groups even in organophosphorus systems (Water, Air, & Soil Pollution 2012, 223: 4221-4231; Journal of the American Society for Mass Spectrometry 2008, 19(8): 1176-1186) and given the importance of the aforementioned functional groups in biological systems, it can be assumed that this characteristic of MZNs may play an important role in carrying molecules of interest.
Therefore, we want to propose a new system for the delivery of substances, in particular pharmacologically active principles, which is proposed as a better alternative to the already known DDS and in particular to those using mesoporous silica nanoparticles, relying on a potential passive targeting system, intrinsic to the material, as well as stable and versatile.
The purpose of the present invention is to provide a system for the administration and delivery of at least one active ingredient, in particular at least one drug of the type having antimicrobial and/or antibacterial and/or bacteriostatic and/or anti-inflammatory and/or mucolytic activity, also called DDS—Drug Delivery System, which is more efficient than traditional vehicle and administration methods and is proposed as an alternative to known systems, using vectors or carriers that allow to overcome the limits of the known ones.
A particular object is to provide a system for the administration and the carrying of such active principles which have a better interaction with the bacterial or biofilm structures in order to be particularly effective against biofilm infections or contaminations.
A further purpose of the invention is to provide a system for conveying the aforementioned molecules, among which can be mentioned, in a non-exclusive way, antibacterial substances, antimicrobial substances, bacteriostatic substances, antibiotics, mucolytic substances, anti-inflammatory substances, etc.
Still another object is to provide a system for the vehicle and administration of drugs which can be obtained starting from carriers having greater availability and therefore greater cost-effectiveness.
These purposes are achieved by a vehicle or transport system for the administration of active substances, for example in particular drugs, which, according to claim 1, comprises a vector or carrier selected from the mesoporous nanoparticles having a surface provided with pores and one or more pharmacologically active ingredients (API) loaded and/or supported in the vector, in which said vector is constituted by mesoporous zirconia nanoparticles (MZN) and said at least one pharmacologically active ingredient is selected from the group comprising the antibacterial substances, the antimicrobial substances, bacteriostatic substances, antibiotics, mucolytic substances, anti-inflammatory substances, etc., including N-acetyl-L-cysteine (NAC), vancomycin, and nitrofurantoin, which can also be used in combinations with each other.
A further object of the present invention is to provide a method for the production of mesoporous zirconia nanoparticles loaded with at least one API.
A still further object of the present invention consists in the use of a system according to the present invention for the eradication of biofilm infections or contaminations (in which API is conveyed closed to and/or near and/or inside the biofilm itself).
Other characteristics and advantages of the invention will be more evident from the description of an embodiment of a DDS system, illustrated by way of example in the accompanying drawings in which:
In its most general form, a drug delivery system according to the invention, also called DDS—Drug Delivery System, comprises molecules having a vector or carrier function selected from mesoporous nanoparticles, in particular mesoporous zirconia nanoparticles MZN and one or more pharmacologically active ingredients, or API—Active Pharmaceutical Ingredient, loaded and/or supported in the nanoparticles of MZN.
The invention comprises, according to at least one version, a system of mesoporous zirconia nanoparticles MZN loaded with at least one API effective against biofilm infections or contaminations and which can—as better explained below—for example act as a so-called “Trojan horse” towards the biofilm itself.
The mesoporous zirconia nanoparticles comprise an internal structure and an external surface and the pores of such mesoporous nanoparticles are present in this internal structure and/or in this external surface.
Mesoporous zirconia nanoparticles (MZNs) loaded with an API, or for example an antimicrobial substance, can permeate the barrier constituted by the biofilm, in particular for example by the exopolymeric substances (EPS) that constitute it, and thus release the API or the antimicrobial substance close to and/or near the bacteria or microorganisms that populate the biofilm. This could depend, in at least one version, on the fact that MZNs can interact directly with the bacterial cell wall thanks to the high affinity of zirconia with phosphate groups.
In one version of the invention, the API can be loaded and/or supported inside the pores, in another version, the at least one API can be adsorbed on the outer surface of the nanoparticles, in a still further version, both possibilities can be present,
In this way, it is possible to overcome at least one of the reasons why biofilms show resistance to antibiotic therapies: as mentioned, in fact, the barrier constituted by the biofilm, and/or in particular by its exopolymeric substances, creates an obstacle to antimicrobial agents, which are delayed by the presence of this structure or neutralized/inactivated by it.
Therefore, the fact that MZNs can cross the barrier would allow to overcome the resistance mechanisms put in place by bacteria and by the biofilm it produces. Furthermore, this facilitates the penetration of the API, both by exploiting the water flow channels and by adhering to the biofilm barrier, as well as by hiding the API or antibiotic substance from enzymes produced by the biofilm itself, efflux pumps and other mechanisms put in place for the inactivation of these substances.
The first experimental tests demonstrated the particular effectiveness of using MZN as a loading system for the indicated APIs: in the experimental conditions used, the APIs proved to be stable and the MZNs inert in terms of reactivity towards the molecules examined.
Therefore, in at least one version of the invention, the dose-dependent adverse effects of at least one API are reduced when such agent is loaded and/or supported in the MZNs. The release process was complete within 24 hours for the loaded and/or supported APIs, making the molecules available to explicit their mechanism of action, particularly improving the eradication action of biofilms.
Furthermore, mesoporous zirconia nanoparticles were found to be inert towards bacteria if not loaded with the API both by antibacterial tests on planktonic strains and by antibiofilm tests on sessile counterparts.
The eradication of preformed biofilms shows an increase in the antibiofilm activity of the API if the latter is loaded and/or adsorbed in the mesoporous nanoparticle and/or supported by the vector. In this state, the API is in fact protected and is released close to and/or near the microbial cells, thus performing improved performances. As a result, the amount of API, such as an antibiotic, required to eradicate biofilm infection or contamination is reduced compared to other methods.
Specifically, at least one of the APIs is selected from the group of molecules with antimicrobial and/or antibacterial and/or mucolytic and/or anti-inflammatory activity, more specifically comprising at least one antibiotic, for example vancomycin, nitrofurantoin and/or other molecules, including N-acetylcysteine or NAC.
It is in fact known that NAC, or N-acetyleysteine, has antioxidant and mucolytic properties and is available on the market in various formulations (PCT/EP2017/082512; WO2018/154091 A1); vancomycin, VCN, is a glycopeptide antibiotic, known to be effective against various pathogenic strains including staphylococci (Scientific Reports 2020 10: 960); Nitrofurantoin (NTF) is a nitrofuran class antibacterial known for therapies for urinary tract infections (Clinical Microbiology and Infection 2017, 23(6): 355-362).
These APIs may be used either individually or in combination with each other or in combination with one or more APIs chosen from those not listed above.
In particular, the combinations can provide for the loading and/or support of more APIs in the same MZN or the combination and/or mixing of MZNs loaded with and/or supporting a first API with MZN loaded with and/or supporting a second API (where the first API is different from the second API), and so on.
The carrier made up of mesoporous zirconia nanoparticles, in fact, is so versatile that more APIs with different properties can be combined and mixed together to improve their overall activity and/or, possibly, to obtain the same activity using a smaller amount of APIs.
However, in the choice of several APIs it is necessary to exclude, or at least carefully evaluate, those combinations that can lead to an antagonism of the active ingredients loaded and/or supported in the same mesoporous zirconia nanoparticles or that are found to act in the same biofilm area, as it can happen, for example for VCN and NAC against S. aureus biofilms.
Therefore, the combination of two or more molecules or APIs must be carefully evaluated, as there may be a direct interaction between the molecules (chemical incompatibility) or a biological antagonism between them.
On the contrary, some combinations can lead to a synergistic effect, such as the combination of MZN loaded with and/or supporting NTF and with NAC (both in the version in which these APIs are loaded together in the same nanoparticles, and in the version in which the first API is loaded and/or supported in a first or first nanoparticles and where the second API is loaded and/or supported in a second or second nanoparticles).
This DDS system, therefore, allows to help the diffusion of at least one API within the biofilm.
Moreover, it is possible to avoid or limit the problems deriving from the chemical incompatibility of different APIs, by loading or supplying each of them in one or more respective mesoporous nanoparticles. In this case, two or more different active ingredients or pharmacologically active ingredients (API) would be provided, and each active ingredient or pharmacologically active ingredient (API) would be loaded and/or supported in one or more mesoporous nanoparticles different from the nanoparticle or nanoparticles in which the other or pharmacologically active ingredient(s) (API) is loaded/supported or loaded/supported.
It has been experimentally observed that for a better interaction between the carrier and the chosen API, or the chosen APIs, the aforementioned nanoparticles, of substantially spherical and/or irregular shape and/or with a specific surface area included in a range between 100 and 500 m2/g, preferably from 150 to 250 m2/g, preferably from 190 to 230 m2/g, must—in at least one version of the invention—have an average pore diameter having a value greater than the size of the API, in so that most of the surface and pore volume of the MZNs are accessible by the API to facilitate their loading.
On the basis of the typical diameters for the APIs indicated above it will be preferable that the nanoparticles have pores with a diameter generally between 2 and 50 nm, but preferably between 2 and 10 nm or between 4 and 6 nm and an average pore volume substantially comprised in a range from 0.2 to 0.4 cm3/g, but preferably between 0.25 and 0.35 cm3/g. In particular, even for large APIs, such as vancomycin, provided that with an apparent molecular diameter lower than the average pore diameter, the API is loaded in weight % varying between 5 and 20% with respect to the weight of the particles.
The protocol used for the synthesis of MZNs is based on a sol-gel process and foresees a molar ratio of the reagents ZB:EtOH:H2O:NaF:HDA pari a 1:750:20:0.02:2 (WO2016120795).
Hexadecylamine (HDA) dissolved in ethanol (EtOH) was used as surfactant, followed by the addition of a sodium fluoride solution NaF 0.1 M and MilliQ water, under stirring and at a temperature between 20 and 25° C. The precursor of zirconium butoxide (ZB) dissolved in ethanol was added dropwise in the first solution under stirring, observing that the mixture turned white due to the formation of insoluble MZNs.
Subsequently, three washing cycles were carried out in EtOH, possibly with demineralized water, recovering the particulate by centrifugation (15 minutes at 12000 ref). The dried powder, suspended in MilliQ water and ethanol, was heated to 170° C. for 20 h.
The collected sample was finally subjected to a thermal vacuum extraction and/or calcination process between 300 and 350° C. to remove the residual surfactant.
In fact, therefore, the synthesis of MZNs includes a sol-gel method with neutral surfactant and the use of an inorganic salt. It is an effective process in which the neutral surfactant helps to define the pores of the MZNs, in combination with a salt to avoid aggregation, a hydrothermal treatment to define the shape of the particles and the extraction of the surfactant, by vacuum and/or high temperatures, in order to avoid the collapse of the pores.
SEM and TEM analyses showed rnesoporous nanoparticles with regular shape, spheroidal appearance and controlled size. These particles are porous, well defined and well separated.
In at least one version, both the shape and the dimensions are uniform.
In another version of the invention, the particles can have an irregular shape and/or size, or a combination with the shape and/or size indicated above.
The high resolution TEM analysis showed roughness on the MZN, probably due to their porosity and partial crystallinity. Several synthesis batches have provided good reproducibility, with an average diameter of the MZNs ranging from 100 to 600 nm, or between 100 and 500 nm, preferably between 200 and 400 nm or between 200 and 300 nm or from 150 to 350 nm.
The presence of surface charges on the s influences the colloidal stability of the nanoparticles and is also dependent on the pH of the solution. Furthermore, the surface charge properties of the vector are important properties to consider in investigating both the loading and release processes of the different APIs.
The surface charge of the MZN was estimated as a function of the pH of the solution. Under acidic conditions at low pH values, the ZP of the MZN was positive (25-30 mV). The number of positive surface charges decreases at higher pH values, with the isoelectric point falling within the range of pH 6.0 to 7.0. Beyond this point the ZP is negatively charged, reaching a plateau of about −30 mV at pH=10.0.
DLS (Dynamic Light Scattering measurements carried out in water at neutral pH showed a hydrodynamic diameter of the nanoparticles from 200 to 650 nm and a polydispersion index (PdI) from 0.3 to 0.6.
A method for the production of the DDS described above initially involves a step of providing mesoporous zirconia nanoparticles (MZNs) and at least one active or pharmacologically active ingredient (API) comprising at least one substance with antibacterial, bacteriostatic and/or bactericidal activity and/or mucolytic and/or anti-inflammatory. Then an impregnation step of the MZNs follows, by dispersing a predetermined quantity of said MZN in water or organic solvent, based on the specific solubility of the API chosen, containing a predetermined quantity of at least one API by obtaining a suspension, subsequent mixing of the suspension with the resulting loading and/or absorption and/or support of the at least one active principle or pharmacologically active ingredient (API) in the pores and/or on the external surface and/or in the inner structure of the MZNs, and a step of separation of the nanoparticles loaded with API through centrifugation or filtration.
The loading step can involve the insertion of the at least one active principle or pharmacologically active ingredient (API) into the pores of the mesoporous zirconia nanoparticles (MZN). This API, as mentioned, can however also be adsorbed or supported by the MZN and/or by their external surface.
For example, in accordance with the solubility of the API, the NAC or the VCN, have been loaded and/or supported starting from aqueous solutions with a known title of API. The loading efficiency was calculated by UV-Vis and quantitative HPLC on the supernatant solution expressed as the ratio between the weight of the loaded and/or supported API and the quantity of MZN.
In the loading protocols used, after each loading, the supernatant solution was separated thus determining the quantity of active ingredient actually loaded or encapsulated. The results and loading conditions are shown in Table 1.
The loading and/or support of the active ingredient was found to be affected by several parameters, such as the solubility and polarity of the API, the solvation properties of the solvent, and the electrostatic interactions with MZNs for the charged drugs.
Among other features, the size, shape and surface area of the API as primary properties play a key role in influencing the theoretical maximum load capacity of the API.
There was good API load capacity in MZNs between 5 and 20% w/w.
For example, the loading efficiency for VCN can vary between 5-15% (weight/weight) or between 8-12% (weight/weight), for NTF between 2-20% (weight/weight) or between 5-15% (weight/weight) while for NAC it can vary between 5-15% (weight/weight) or between 7-13% (weight/weight).
Plate antimicrobial tests were conducted to verify the inactivity of the nanoparticles and to confirm that the antibacterial activity is linked to being loaded with at least one API. The negative control corresponds to S. aureus and K. pneumoniae without API.
In particular, MZNs are completely inactive if not loaded against both strains.
NAC does not exhibit antibacterial activity below 1-2 mg/ml, being a mucolytic agent.
The eradication tests were performed by adding free or loaded and/or supported API after the maturation of a biofilm for 24 hours.
VCN was tested against S. aureus and NTF against T. pneumoniae.
Table 2 below shows the main results regarding the Log Reduction of preformed biofilm live cells at the highest concentrations tested for each API agent.
The log reduction was calculated according to the following formula:
Log reduction (LR)=Log10(mean number of CPUs without reatment)/(mean number of CFUs after treatment), where CFUs are Colony Formation Units.
Correspondingly, the eradication percentage P was calculated according to the following formula:
P(%)=[1−(10−LR)]*100
S. aureus and
K. pneumoniae
S. aureus
S. aureus
K. pneumoniae
K. pneumoniae
In particular, loaded and/or supported APIs show a greater log reduction of at least 1 when compared with the same concentration of free API.
The graphs in
Finally,
In general, therefore, the loading process on MZN allows to mix APIs with different solubilities and behaviours, such as NTF and NAC in the proposed example, obtaining a better eradication of the biofilm.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102020000023665 | Oct 2020 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2021/059199 | 10/7/2021 | WO |
