CN114805862A

CN114805862A - Recyclable temporary corneal prosthesis or contact lens based on modified PVA derivative hydrogel material

Info

Publication number: CN114805862A
Application number: CN202210551684.9A
Authority: CN
Inventors: 潘佳耿; 林泽群; 欧阳宏; 张旺; 高粱
Original assignee: Guangdong University of Technology; Zhongshan Ophthalmic Center
Current assignee: Guangdong University of Technology; Zhongshan Ophthalmic Center
Priority date: 2022-05-18
Filing date: 2022-05-18
Publication date: 2022-07-29
Anticipated expiration: 2042-05-18
Also published as: CN114805862B

Abstract

The invention discloses a recyclable temporary corneal prosthesis or contact lens based on a modified PVA derivative hydrogel material, and belongs to the technical field of gel materials. The invention utilizes aldehyde compounds to modify activated polyvinyl alcohol, the obtained product is placed in saturated sodium carbonate solution for termination reaction, the precipitated white solid is subjected to impurity removal and freeze drying, and white particles, namely modified polyvinyl alcohol gel materials, are obtained; wherein the usage amount of the aldehyde compound is 20-30% of the amount of hydroxyl substances in the polyvinyl alcohol. The material as a human cornea donor material has the advantages of controllable phase separation, plasticity, high water content, high transparency, mechanical adaptation, high permeability, repeated recovery, convenient preparation, capability of suturing and the like, and is a temporary cornea substitute with good nutrition conveying effect and good biocompatibility.

Description

Recyclable temporary corneal prosthesis or contact lens based on modified PVA derivative hydrogel material

Technical Field

The invention belongs to the technical field of gel materials, and particularly relates to a recyclable temporary corneal prosthesis or contact lens based on a modified PVA (polyvinyl acetate) derivative hydrogel material.

Background

According to The World Health Organization (WHO), more than 1000 million patients suffer from vision impairment and vision loss due to corneal diseases or injuries every year, keratoplasty is The most important treatment method, and Penetrating Keratoplasty (PKP) is The current mainstream transplantation operation (The Lancet 379.9827(2012): 1749-. In 2012, the international eye library association counted 116 national corneal transplants, and about 185000 corneal transplant cases were found. In recent years, even more serious, it is estimated that 1270 ten thousand people wait for corneal transplantation every year worldwide, and only one of 70 of these needs is satisfied. The severe scarcity and low inventory of donors results in many patients missing the opportunity for repeat or elective surgery. Meanwhile, even in the presence of human cornea donors, a series of problems such as postoperative infection, immunological rejection and the like follow, so that the development of artificial cornea products is urgently needed for patients and doctors.

Keratoprosthesis products are mainly classified into two types according to their sources: one is a tissue engineering artificial cornea based on natural materials; the other is a fully synthetic keratoprosthesis based on synthetic materials. The tissue engineering artificial cornea is prepared from acellular biological tissues as raw materials, and commonly comprises pigs, fish scales, human skin, amnion and the like. The main problems with this strategy are: the natural material source is limited, and the foreign body protein can generate strong immunological rejection and the like. More importantly, the cornea made of the natural material can be degraded in a short period after transplantation, the transparency is insufficient, so that the recovery window period of a patient is not matched with the service life of the material after transplantation, and the quality of life is not improved well. Therefore, the artificial cornea based on the synthetic material is produced, and the artificial cornea is subjected to excellent performance modification in the aspects of biocompatibility, permeability, mechanical compliance and the like, and becomes a new generation material for replacing human cornea. At present, the total synthetic artificial cornea mostly adopts Polyhydroxyethylmethacrylate (PHEMA), polymethyl methacrylate (PMMA), silica gel and the like, and then is matched with a peripheral bracket to simulate the structure of the human cornea. These materials do not degrade in physiological environments, thus providing a relatively long window for the patient to wait for the corneal donor, while the high water content ensures oxygen delivery efficiency. However, at the level of recycling, these polymers are not recyclable, since they are covalently crosslinked products, leading to a drastic increase in the content of environmental micropolastics; secondly, most raw materials are copolymers, and because the specific reaction principle of the raw materials is uncertain, the possibility of residual monomers exists, and the molecular weight is not well controlled. Finally, their mechanical properties are largely not well adapted to the natural cornea, and many suffer from clinically significant limitations due to their mechanically soft and brittle nature and lack of suturability.

At the global environmental pollution level, in the last decade, artificial cornea replacements or contact lenses are often discarded directly after use. Thus, a large amount of plastic waste, which is difficult to degrade, is generated. These materials, when they lose some structural strength, physically break down, which results in smaller plastic particles, ultimately leading to the formation of micro-plastics, which may subsequently harm the soil ecosystem, pose an ecological risk, and may lead to the accumulation of persistent toxic pollutants in fragile organisms such as worms and birds, causing a top-of-the-chain crisis. Research at the american asian-sonna state university indicates that a pair of contact lenses can be found approximately every 2 pounds of sludge. In 2019, great manpower and material resources are consumed by pushing a contact lens recovery plan in England, and plastic wastes are recycled to reduce the amount of wastes.

Therefore, it is important to develop a non-covalently crosslinked hydrogel having recycling properties. Non-covalent bonding gels involve ionic bonds, are unstable in PBS buffer solutions, and also involve hydrogen bonds, and unstable structures easily disintegrate and collapse under water at high temperatures, so that non-covalent physically cross-linked gels of hydrophobic interactions become the preferred material. The hydrogel formed by modifying a hydrophilic main chain by a hydrophobic alkyl side chain is called as hydrophobic association physical gel (SAHs), has mechanical compliance, optical adaptation, recoverability, stability and processability, and can well meet the necessary requirements of corneal transplantation. On the other hand, the corneal graft must be porous, as porosity allows nutrients to be provided to the corneal cells through the gel, maintaining ocular function.

However, it is noteworthy that hydrophobic association gels have been opaque in the past (Chemical Engineering Journal362(2019): 325-.

It is clear that porosity can increase the rate of passage of small molecule species through the gel, i.e., the gel has a high permeability. The existing gel pore-forming strategies include gas foaming (Soft Material 6.8(2010):1785-

PartB: Physics 50.2(2010):340-The size is often larger than 1 micron, and organic solvents are needed, causing pollution, being easily influenced by the process and the parameters of polymer solution, and the flow is complex and not beneficial to mass production. It is noteworthy that the more the channels are distributed, the more scattering sites of light will inevitably increase, so that few photons are transmitted, resulting in the opacity of most porous hydrogel films. And when the pore size is designed, the pore size of the gel should be larger than the molecular volume of nutrient molecules (oxygen, inorganic salts, amino acids, glucose and the like) and smaller than the Rayleigh scattering limit. Such porosity can ensure nutrient penetration and transparency. The hydrothermal pore forming technology is not reported in the hydrophobic association gel technology, and the method can regulate and control the porosity, form pores with the size of hundreds of nanometers, completely meet the penetration of nutrient molecules and ensure the transparency.

In general, there is still a need for a rapid substitute for cornea used in war or accidental injury, which can provide more sufficient time for human cornea donor to wait, and meet the demand of people for ideal cornea function.

Disclosure of Invention

Based on the above, the invention provides a recyclable temporary corneal prosthesis or contact lens based on a modified PVA derivative hydrogel material, and the temporary corneal prosthesis or contact lens which is controllable in phase separation, plastic in shape, high in water content, high in transparency, adaptive in mechanics, high in transparency, recyclable, convenient to prepare, suturable and good in nutrition delivery effect and biocompatibility is developed. The problem of shortage of emergency corneal transplantation materials under the condition of tension of a human corneal donor is solved, sufficient time is provided for a secondary transplantation operation, and meanwhile, the technical problems of material in aspects of optomechanics mismatch and the like are solved.

In order to achieve the purpose, the invention provides the following technical scheme:

a modified polyvinyl alcohol gel material is prepared by modifying activated polyvinyl alcohol with aldehyde compound, placing the obtained product in saturated sodium carbonate solution for termination reaction, removing impurities from the precipitated white solid, and freeze-drying to obtain white particles, i.e. the modified polyvinyl alcohol gel material; wherein the usage amount of the aldehyde compound is 20-30% of the amount of hydroxyl substances in the polyvinyl alcohol.

Further, the aldehyde compound is one of pentanal, hexanal, heptanal and octanal.

Further, the activation is specifically: mixing polyvinyl alcohol with anhydrous grade dimethyl sulfoxide (DMSO), heating to dissolve, cooling, adding catalyst, and stirring.

Further, the mass volume ratio of the polyvinyl alcohol to the anhydrous grade dimethyl sulfoxide is 3 g: 100 mL.

Further, the catalyst is used in an amount of 2% of the amount of hydroxyl species in the polyvinyl alcohol.

Further, the catalyst is p-toluenesulfonic acid monohydrate.

The invention also provides a preparation method of the modified polyvinyl alcohol gel material, which comprises the following steps:

1) mixing polyvinyl alcohol with anhydrous grade dimethyl sulfoxide, heating and dissolving at 90 ℃, cooling the obtained solution to 60 ℃, adding a catalyst, and stirring to obtain an activated polyvinyl alcohol solution;

2) the aldehyde compound is dripped into the activated polyvinyl alcohol solution, stirred and reacted for 3h, then poured into 500mL saturated sodium bicarbonate solution (enough sodium bicarbonate solid is added into deionized water until the sodium bicarbonate solid can not be dissolved, and then filtered to obtain supernatant, namely the saturated sodium bicarbonate solution) to stop reaction, white solid is separated out, impurities are removed, and the white particles, namely the modified polyvinyl alcohol gel material, are obtained after freeze drying.

Further, the impurity removal specifically comprises: and cutting the white solid into pieces, washing with deionized water, drying, dissolving in anhydrous dimethyl sulfoxide, pouring the obtained solution into the deionized water again, separating out the white solid again, and repeating the operation.

The invention also provides application of the modified polyvinyl alcohol gel material in preparing a corneal prosthetic material or a contact lens material.

The invention also provides a preparation method of the corneal prosthesis material, which comprises the following steps:

1) the modified polyvinyl alcohol gel material is added into anhydrous N, N-Dimethylformamide (DMF) with the dosage of 100mg/mL, and stirred for 12 hours at 90 ℃ until being dissolved, so as to obtain a transparent homogeneous solution with the concentration of 100 mg/mL. Ultrasonic processing is carried out for 30min under the conditions that the frequency is 40kHz and the power is 300W, degassing is carried out for 1h in a vacuum drying oven to completely remove air bubbles, centrifuging is carried out, the transparent solution is injected into a customized quartz glass mold with the depth of 4mm by a pouring method, then the customized quartz glass mold is placed in a closed saturated lithium chloride solution environment for 3 days at the room temperature (25-27 ℃) to obtain a transparent gel material, and the transparent gel material is obtained by the process that DMF (solvent) -water vapor (poor solvent) are continuously exchanged and distributed to induce the modified polyvinyl alcohol gel material/DMF solution to be converted into transparent gel;

2) peeling the prepared transparent gel from the quartz glass mold, immersing the transparent gel in a large amount of deionized water for at least 3 days, and replacing the deionized water every day to completely remove any soluble substances such as DMF and the like to obtain a highly transparent hydrogel film;

3) and (3) soaking the highly transparent hydrogel film in deionized water at 90 ℃ for 12h to achieve a thermodynamic stable state and a pore-forming effect, quenching the highly transparent hydrogel film, and storing the hydrogel film in phosphate buffered saline (PBS, with the pH value of 7.4) to obtain the corneal prosthesis material.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a polyvinyl alcohol gel material based on hydrophobic short alkane chain grafting modification, which integrates multiple properties and is used as a temporary membrane corneal prosthesis or a contact lens substitute material. The invention ensures high permeability through a novel hydrothermal pore-forming strategy, so that the formed gel material has high transparency, polydisperse nano-pores, high permeability, high water content, capability of being sewed, good tensile strength and processability adaptive to personalized geometric shapes, and more importantly, the gel material can be recycled and repeatedly prepared without degradation, thereby avoiding secondary biological pollution infection risk and environmental micro-plastic pollution.

The polyvinyl alcohol used in the invention has low price and hydrophilicity, the aldehyde compounds such as octanal can be extracted from fruits, and the polyvinyl alcohol has aromatic flavor and no toxicity, and can play a role in hydrophobic association crosslinking when used for modifying the polyvinyl alcohol.

The materials are convenient to obtain and environment-friendly, and the prepared materials can be transplanted and separated to form a highly transparent film, so that the method is greatly different from most of the conventional SHAS gel in a non-visual manner.

The invention has the advantages that the hydrothermal treatment of the gel material is an effective, controllable and novel pore forming strategy, a pore-forming agent is not required to be added, the pollution of chemical substances is reduced, the production cost is reduced, the technical conditions such as 3D printing and the like are not involved in the process, the requirement on equipment is lower, and the preparation process is simple.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a flow chart for the preparation of PVA-C8-gel;

FIG. 2 shows the reaction equation of PVA-C8 and ¹ HNMR spectrographic analysis;

FIG. 3 is SEM of PVA-C8 and PVA-C8-gel before and after hydrothermal treatment;

FIG. 4 is a water content and water contact angle performance test of various materials;

FIG. 5 is a stress-strain curve for various materials;

FIG. 6 is an ultraviolet-visible (UV) spectrum of different materials;

FIG. 7 is the nutrient permeability of PVA-C8-gel;

FIG. 8 is a CCK8 toxicity test of PVA-C8-gel;

FIG. 9 is a diagram of the shaping of PVA-C8-gel;

FIG. 10 is a photograph of corneal sutures;

FIG. 11 is a slit lamp photograph of rabbit cornea after keratoprosthesis material transplantation; the left is the keratoprothesis material (PVA-C8-gel) group, and the right is the allograft group;

FIG. 12 is an OCT image of rabbit cornea after transplantation; the left is the keratoprothesis material (PVA-C8-gel) group, and the right is the allograft group;

FIG. 13 is a flow chart of the recycling and reshaping of PVA-C8-gel.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The polyvinyl alcohol (PVA) used in the invention is commercial polyvinyl alcohol, and the molecular weight Mw is 3000-.

The present invention defines the finished gel molded, i.e. the temporary total corneal substitute (keratoprosthesis), as PVA-Cn-gel (n ═ 5, 6, 7, 8). In the following example 1, when n is 8, i.e. octanal, the test was carried out, and in fact, the effects achieved by n-5, 6, 7, 8 were similar and could be used as alternative starting materials.

The commercially available contact lenses used in the present invention were purchased commercially, and besom SofLens 59 monthly was cast at 100 degrees.

The rabbit cornea used in the invention is a cultured rabbit cornea.

Example 1

1. Preparation of modified polyvinyl alcohol gel material

1) Taking 6g of polyvinyl alcohol (PVA) particles, putting the PVA particles into a 250mL round-bottom flask, adding 200mL of anhydrous grade dimethyl sulfoxide (DMSO), and heating at 90 ℃ to dissolve the PVA particles; cooling the PVA solution to 60 ℃, then adding 0.43g of p-toluenesulfonic acid monohydrate, and stirring for 1h to obtain an activated PVA solution;

2) 2.2mL of octanal is dripped into the activated PVA solution, the mixture is continuously stirred for 1h, and then the mixture is poured into 500mL of normal-temperature saturated sodium bicarbonate solution for terminating the reaction, and white solid is separated out at the moment; cutting the precipitate, replacing deionized water at irregular period, soaking, and cleaning for 3 times; and drying the white solid, dissolving the white solid in 100mL of DMSO again, pouring the obtained solution into deionized water again to separate out the white solid, wherein the process is to further remove impurities such as small organic molecules embedded in the solid, shearing the precipitate, soaking the precipitate in the deionized water, repeating the process for 3 days, changing water three times a day, and finally, freeze-drying to obtain white particles, namely the modified polyvinyl alcohol gel material, wherein the product of the polyvinyl alcohol modified by octanal is named as PVA-C8.

2. Preparation of corneal prosthetic material

1) Adding the prepared PVA-C8 particles into anhydrous N, N-Dimethylformamide (DMF) in an addition amount of 100mg/mL, and stirring for 12 hours at 90 ℃ until the particles are dissolved to obtain a transparent homogeneous solution with the concentration of 100 mg/mL; the solution was sonicated (frequency 40kHz, power 300W, time 30min) and degassed in a vacuum oven for 1h to remove bubbles completely. Centrifuging on a centrifuge, injecting the transparent solution into a customized quartz glass mold with the depth of 4mm by a pouring method, and exposing for 4 days in a saturated lithium chloride solution at room temperature (25-27 ℃) to obtain transparent gel;

2) peeling the transparent gel from the quartz glass mold, immersing the transparent gel in a large amount of deionized water for 3 days, and replacing the deionized water every day to completely remove any soluble substances such as DMF and the like to obtain a highly transparent hydrogel film, which is defined as SAH;

3) SAH was soaked in 90 ℃ deionized water for 12h, then quenched (SAH was transferred from 90 ℃ hot water to 15 ℃ deionized water for 1h) and stored in PBS (pH 7.4), which is defined as PVA-C8-gel, and the operational schematic is shown in fig. 1 below.

Test examples

1. Nuclear magnetism

The starting material PVA-C8 was characterized using a Bruker400 MHz NMR instrument to confirm that the post-modification of PVA, i.e.the grafting of short alkanes onto polyvinyl alcohol, was accomplished as follows: using d ₆ -DMSO as a solvent, 6mg of PVA-C8 was added, and dissolution was completed at 70 ℃ to carry out ¹ HNMR spectroscopic analysis, as shown in FIG. 2.

As can be seen from FIG. 2, the modification ratio of PVA-C8 was 20% (degree of degradation, DS, 2X) ₂ /(X ₁ +2X ₂ ) X100%, molecule 2X in the formula ₂ Represents the number of side-chain-substituted hydroxyl groups, denominator X ₁ +2X ₂ Representing the total number of hydroxyl groups of the polyvinyl alcohol, the modification ratio DS is defined as the ratio of the number of substituted hydroxyl groups to the total number of hydroxyl groups), and the modification ratio DS is generally determined by ¹ The peak integrated area of the HNMR spectrum is calculated equivalently, i.e., DS will be calculated using the following formula:

A ₁₂ refers to the area of hydrogen atoms contained in carbon number 12, where the value is 1, A ₂₊₄ This means the area of hydrogen atoms contained in carbon Nos. 2 and 4, and the value is 3.35, and the DS is calculated to be 20%.

It will further be ensured that the finished temporary total cornea substitute (PVA-C8-gel) has a relatively high water content. The modification rate is not too high because the alkane side chain has certain hydrophobicity.

2. Hydrothermal pore formation leads to high permeability

Scanning electron microscopy (SEM, hitachi SU8220) instruments were used. PVA-C8 was freeze dried and then fractured in liquid nitrogen to give a cross-section of PVA-C8 and the freshly exposed cross-section was topographically characterized. The results are shown in FIG. 3.

During gelation (i.e., SAH film formation process) involving nucleation and growth mechanisms, a quenched depth of phase separation is rapidly obtained in a shallow water vapor-induced effect, and during this low solvent-non-solvent exchange, the molecules or small aggregates formed can be fixed in a transferable state in the shallow depth of phase separation by "percolation", resulting in a relatively low level contrast of dense and sparse polymer regions, thereby suppressing light scattering and increasing transparency. Thus, as can be seen in fig. 3, the SEM image of SHA is dense and non-porous.

Whereas when SAH gels are hydrothermally treated, the isotropic boundary limits and kinetic equilibrium are broken. The equilibrium of hydrophobic and hydrophilic interactions is again shifted and reaches a critical point, causing the gel to undergo another density increase and decrease in the phase domain, forming a new chemical potential equilibrium, eventually leading to a significant increase in the contrast of the dilute and concentrated phases, i.e. creating polydisperse nanopores, so that the SEM of the PVA-C8-gel membrane is porous, as can be seen from fig. 3.

This will ensure good performance of PVA-C8-gel in mass transfer, avoiding malnutrition and severe inflammation after transplantation.

3. Good hydrophilicity

A 1 μ l DROP of water was deposited onto the test sample using a standard automatic goniometer (290, rame-hart Inc.) and the final image of the liquid-air interface was analyzed using DROP image processing software to calculate the water contact angle to characterize hydrophilicity, the experimental results are shown in fig. 4.

As can be seen from FIG. 4, the surface air interface of PVA-C8-gel has a contact angle with water of about 55 °, and has a close contact angle with water and better hydrophilicity compared with soft contact lenses. The hydrophilic PVA-C8-gel has been shown to potentially attract moisture, to be soft to the touch, to provide the necessary conditions for the epithelial cells of the cornea to transport oxygen amino acids, etc.

4. High water content property

The equilibrium water content of PVA-C8-gel was measured according to the following method. A sample of PVA-C8 was soaked in deionized water for 12 h. After rapid blotting of the hydrogel with filter paper to remove surface water, the mass of the wet sample was measured with an electronic scale (M) _t ) The gel was then freeze dried and the dry sample mass (M) was measured using an electronic scale ₀ ). The equilibrium moisture content of the sample was calculated according to the following equation:

in the formula, M ₀ Mass of PVA-C8-gel after lyophilization, M _t The results are shown in FIG. 4 for the mass of PVA-C8-gel measured after 1 day of equilibration in deionized water. (commercially available contact lenses are control groups).

As can be seen in FIG. 4, the equilibrium moisture content of PVA-C8-gel was substantially stabilized at about 47%, which is close to that of soft contact lenses. Water content in the range of 40-50% is sufficient to select this type of gel as a temporary whole cornea replacement. Unexpectedly, the increase in porosity had little effect on the water content, with the water content of both PVA-C8-gel and SAH being around 44 (+ -3) wt.%. Namely PVA-C8-gel and SAH have almost the same composition.

5. Strong and tough mechanical property

Performing tensile test with a Pearl sea SANS (CMT2203) tensile machine, and adjusting constant temperatureThe water bath was 37 ℃ and the stretching test was carried out using PVA-C8-gel having a length of 20mm, a width of 6mm and a thickness of 500. mu.m, while the stretching rate was fixed at 0.17s ^-1 Until it broke, and stress-strain curves were plotted as shown in fig. 5 (contact lenses and rabbit corneas were treated with the same mechanical procedure as controls).

As can be seen from FIG. 5, PVA-C8-gel exhibited the characteristics of an elastic material that achieved high strain (tensile ratio λ up to 16), toughness (breaking stress σ f up to 2.5MPa), high Young's modulus (E can be up to 0.5MPa), and comparable contact lenses, PVA-C8-gel exhibited tough mechanical properties, fully fitting corneal transplants, including accommodating suture pull and increased intraocular pressure.

6. High transparency performance

The PVA-C8-gel was subjected to ultraviolet-visible (UV) spectroscopy using an ultraviolet-visible spectrophotometer (Perkinelmer Lambda 950), the spectral range was set to 250-800nm, the light transmission (Transmission, T) was measured, and the optical curve was plotted as shown in FIG. 6. The gel specimens tested were 15mm in diameter and uniform 500 μm thick (contact lenses and rabbit corneas were treated in the same manner as controls).

As can be seen from fig. 6, PVA-C8-gel showed high light transmission, T92% -95% at 700nm, matching the transparency of rabbit cornea (T86%) and human cornea (T91%), which is also comparable to contact lenses.

7. Good nutrient permeability

The permeability of the material is generally tested by using a self-made permeation tank according to a tank membrane permeation principle, and the invention tests the delivery of three nutrient substances of glucose, tryptophan and sodium chloride, wherein the specific operations are as follows: the test procedure was carried out at 37 ℃ and the study was carried out using a horizontal glass diffusion cell (PermeGear) having two chambers, one donor cell and one receiving cell. The structure sizes of the supply tank and the receiving tank are the same, the tank walls at the joint of the supply tank and the receiving tank are provided with a round hole with the diameter of 1cm, and the two tanks can be tightly combined by using a screw connection at the joint of the tank walls, so that a complete channel is manufactured. Before testing, PVA-C8-gel clear film (500 μm thick) was soaked overnight in deionized water at 37 ℃ to thoroughly reach an equilibrium swollen state, and then the gel samples were placed between the two chambers and subjected to sampling tests on the receptor cells at specified time intervals (i.e., 5 experiments were performed with 12h permeation time per group). During the whole osmosis measurement process, all the solution is continuously stirred by the magnetic rotor to provide uniform solute distribution and reduce boundary stratification of nutrients, and the whole osmosis process is carried out in a constant temperature environment of 37 ℃.

1) Glucose permeation

The donor cell was filled with glucose nutrient solution (30mL of 50mg/mL glucose solution), the recipient cell was filled with 30mL of deionized water, the magnetic stirrer was turned on, and the timer was started. A total of 3 experiments were performed, each run at 12h permeation time, after which the receptor wells were sampled and analyzed in combination with a glucose content detection kit (Solarbio, 100T/96S) and a UV-visible spectrophotometer (Perkinelmer Lambda 950) to measure the absorbance at 505nm, the results being the average of five independently run experiments.

As can be seen from FIG. 7, the PVA-C8-gel film had a glucose permeability similar to that of the human cornea, i.e., 2.1X 10 ^-6 cm ² (the glucose permeability of the human corneal stroma is about 2.5X 10) ^-6 cm ² /s)。

2) Tryptophan penetration

The donor cell was filled with tryptophan nutrient solution (30mL of 0.5mg/mL L-tryptophan solution) and the recipient cell was filled with the same volume of deionized water to maintain the volume of solution in the recipient cell constant. The magnetic stirrer was started and the timer was started. A total of 3 sets of experiments were performed, with a 12h permeation time for each set, after which the receptor pools were sampled. And 0.01, 0.02, 0.03, 0.04 and 0.05mg/mL tryptophan standard solutions are prepared, the absorbance value is measured at 280nm to obtain a standard curve, and the concentration of the permeated tryptophan is calculated from the standard curve, so that the result is the average of five independent running tests.

As can be seen from FIG. 7, the PVA-C8-gel film had a tryptophan permeability similar to that of the human cornea, i.e., 49.6X 10 ^-7 cm ² (Tryptophan permeability of human corneal stroma)About>10 ^-7 cm ² /s)。

3) Sodium chloride osmosis

The donor cell was filled with sodium chloride nutrient solution (30mL of 0.9% sodium chloride solution), the recipient cell was then filled with 30mL of deionized water to maintain the volume of solution in the recipient cell constant, the magnetic stirrer was turned on, and the timer was started. After 3 sets of experiments, each set having a permeation time of 12h, the receptor cells were sampled and analyzed computationally using a conductivity meter (CT-3031), the results being an average of five independent runs.

As can be seen from FIG. 7, the PVA-C8-gel film had a sodium chloride permeability similar to that of the human cornea, i.e., 8.83X 10 ^-7 cm ² (sodium chloride permeability of human corneal stroma about)>10 ^-7 cm ² /s)。

8. Low cytotoxicity

A100. mu.L corneal epithelial cell (HCE-2) cell suspension having a density of 5000 cells/mL was prepared in a 96-well plate. The plates were incubated in an incubator for 24 hours (37 ℃ C., 5% CO) ₂ ). Adding PVA-C8-gel, soaking in complete culture medium at 37 deg.C for 48 hr to obtain leaching solution; the plates were incubated in the incubator for a period of time (1/3/7 days for a total of 3 time points). Adding reagent at a ratio of 10 μ L of CCK-8 solution (Cell Counting Kit-8(CCK-8 Kit), G4103-1ML) per 100 μ L of Cell culture fluid, and incubating for 2h in a Cell incubator; (care was taken not to generate bubbles in the wells which would affect the OD reading) and finally the absorbance was measured in a microplate reader at a wavelength of 450 nm. The results are shown in FIG. 8.

As can be seen from FIG. 8, the column chart of PVA-C8-gel shows that the material has less cytotoxicity to corneal epithelial cells, has good biocompatibility and can be used for further corneal transplantation.

9. Plastic formability

The transparent hydrogel PVA-C8-gel is placed in a matched polytetrafluoroethylene mould (the radius of a base arc is 8.6mm, and the total diameter is 15mm) which is polished in a customized way, and is fixed by a stainless steel clamp, so that the functions of shaping and balanced pressure application are realized. Then the whole set of mould is placed in hot water at 90 ℃ for 1h, and then the mould is quickly transferred to water at 25 ℃ for soaking for 1 h. After unloading, the clamp, the mold and the gel are removed in sequence, and the transparent film with a certain radian is obtained, which shows that the gel PVA-C8-gel can effectively simulate the radian of the human cornea and be used for in vivo transplantation, and the same is also applicable to other shaping with different carbon numbers (n is 5, 6 and 7), wherein a shaping picture is shown in figure 9, and the three figures are taken at different angles.

As can be seen in FIG. 9, PVA-C8-gel can be modeled to resemble a human cornea in curvature, making the shape biomimetic, and can be used for further corneal transplantation.

10. Seamable property

PVA-C8-gel hydrogel was implanted into a manually created corneal graft, i.e., a full thickness corneal tissue of 6mm in diameter was removed intact using trephine and corneal scissors, and PVA-C8-gel was sutured intermittently to the corneal defect using 10-0 monofilament nylon suture.

As can be seen from fig. 10, PVA-C8-gel can be completely sutured by a 10-0 monofilament nylon suture, is mechanically adapted, can be pulled without being broken, and can be matched with a clinician to smoothly complete the operation on the corneal transplantation operation.

11. In vivo whole cornea transplantation and evaluation thereof

The operations of animal care, breeding, operation and euthanasia of New Zealand white rabbits are approved by the ethical committee of the Zhongshan ophthalmic animal of the Zhongshan university. 18 male adult rabbits were randomly divided into experimental and control groups of 9 rabbits each, and left eye was selected as the operated eye (receiving PKP treatment) and right eye was selected as the healthy control eye. After anesthetizing the rabbits, the experimental group received PKP treatment with PVA-C8-gel lenses and the control group received PKP treatment with allogeneic corneal implants. All groups were made with 10-0 sutures to make a 6mm diameter corneal wound and the graft material was a matched size PVA-C8-gel lens (thickness around 550 μm). Tobramycin dexamethasone eye drops are used for anti-inflammatory and anti-infective treatment three times a day in the first week after operation, and then gradually decrease in 21 days. After operation, all rabbit eyes were observed daily for local redness and swelling and secretion. Detailed ophthalmic examinations were performed under

general anesthesia

1, 2, 3 weeks after surgery, observing graft in situ, translucency and corneal inflammation, neovascularization: including photographs of bright field cornea and sodium fluorescein corneal staining under cobalt blue light taken with a slit lamp (YZ5S,66 Vision Tech) and evaluation of intrastromal position and corneal thickness of the transplanted structures with an Optical Coherence Tomography (OCT), the postoperative pictures are shown in fig. 11 and 12.

As can be seen from FIGS. 11 and 12, the PVA-C8-gel artificial cornea transplanted after the operation exhibited a higher light transmittance from the image taken by the slit lamp on day 21. From the OCT image, the change of edema, hyperplasia and the like at the position of the transplant material can be clearly observed, and the change of the whole thickness of the cornea is also not observed, which shows that the PVA-C8-gel can replace the cornea donor in a certain time and has great clinical application value.

12. Cornea prosthesis recovery, regeneration and cyclic utilization

The PVA-C8-gel corneal prosthesis can be recovered, namely, after the PVA-C8-gel corneal prosthesis is used for one time, the corneal prosthesis is uniformly collected and sheared, then the clear homogeneous solution is prepared by dissolving the corneal prosthesis with anhydrous DMF (at 90 ℃), then the corneal prosthesis is manufactured again according to the preparation process of the first part in the technical solution, a series of operations such as shaping and the like are completed, and the whole process is shown in figure 13.

As can be seen from figure 13, the recovery process is simple, no biological secondary pollution is caused, the disposable use is realized, the cross infection is avoided, the raw materials are biochemically used, and the clinical promotion of the corneal prosthesis is facilitated.

The above description is intended to be illustrative of the present invention and should not be taken as limiting the invention, as the invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims

1. A modified polyvinyl alcohol gel material is characterized in that aldehyde compounds are used for modifying activated polyvinyl alcohol, the obtained product is placed in a saturated sodium carbonate solution for termination reaction, the precipitated white solid is subjected to impurity removal, and freeze drying is carried out to obtain white particles, namely the modified polyvinyl alcohol gel material; wherein the usage amount of the aldehyde compound is 20-30% of the amount of hydroxyl substances in the polyvinyl alcohol.

2. The modified polyvinyl alcohol gel material of claim 1, wherein the aldehyde compound is one of pentanal, hexanal, heptanal, and octanal.

3. The modified polyvinyl alcohol gel material according to claim 1, wherein the activation is in particular: mixing polyvinyl alcohol with anhydrous dimethyl sulfoxide, heating to dissolve, cooling, adding catalyst and stirring.

4. The modified polyvinyl alcohol gel material of claim 3, wherein the mass to volume ratio of polyvinyl alcohol to anhydrous grade dimethyl sulfoxide is 3 g: 100 mL.

5. The modified polyvinyl alcohol gel material of claim 3, wherein the amount of the catalyst is 2% of the amount of hydroxyl species in the polyvinyl alcohol.

6. The modified polyvinyl alcohol gel material of claim 3, wherein the catalyst is p-toluenesulfonic acid monohydrate.

7. A method for preparing a modified polyvinyl alcohol gel material according to any one of claims 1 to 6, comprising the steps of:

2) and dripping the aldehyde compound into the activated polyvinyl alcohol solution, stirring for reacting for 3h, then pouring into a saturated sodium bicarbonate solution for terminating the reaction, separating out a white solid, removing impurities, and freeze-drying to obtain white particles, namely the modified polyvinyl alcohol gel material.

8. The preparation method according to claim 7, wherein the impurity removal is specifically: and cutting the white solid into pieces, washing with deionized water, drying, dissolving in anhydrous dimethyl sulfoxide, pouring the obtained solution into the deionized water again, separating out the white solid again, and repeating the operation.

9. Use of the modified polyvinyl alcohol gel material according to any one of claims 1 to 6 for the preparation of a keratoprosthetic material or a contact lens material.

10. A preparation method of a corneal prosthetic material is characterized by comprising the following steps:

1) dissolving the modified polyvinyl alcohol gel material of any one of claims 1-6 by using anhydrous N, N-dimethylformamide, carrying out ultrasonic treatment, defoaming, centrifuging, pouring, and then placing in a closed saturated lithium chloride solution environment for 3 days to obtain a transparent gel material;

2) and (3) cleaning the transparent gel material by using deionized water, then soaking the transparent gel material in deionized water at the temperature of 90 ℃ for 12h, and then quenching and storing the gel material in phosphate buffer saline solution with the pH value of 7.4 to obtain the corneal prosthesis material.