CN111588514B - Method for preparing artificial cornea central part through photocatalysis - Google Patents
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
- A61F2/142—Cornea, e.g. artificial corneae, keratoprostheses or corneal implants for repair of defective corneal tissue
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Abstract
The invention discloses a method for preparing the central part of an artificial cornea by photocatalysis, which mainly solves the problems that the optical center of the artificial cornea generates calcium precipitation, cell adsorption and protein adsorption after being implanted, the traditional reaction steps are complex, the types of system solvents are various, the reaction temperature is higher, and the like. The technical scheme provided by the invention adopts a modification liquid for the optical center of the artificial cornea, which comprises the following components: glycidyl methacrylate, a photocatalyst, a reaction solvent and a chain transfer agent. The invention has the beneficial effects that the invention carries out the activity controllable free radical polymerization under the initiation of visible light, so the reaction condition is mild and the reaction is controllable. The polyvinyl alcohol modified by glycidyl methacrylate can be subjected to ring-opening grafting (acidic environment and alkaline environment) with a plurality of substances with hydroxyl and amine groups. In addition, the epoxy group is very stable in a room temperature environment, and ring opening phenomenon cannot occur. Therefore, the method is very suitable for surface modification of biomedical materials.
Description
Technical Field
The invention relates to a method for preparing a central part of an artificial cornea by photocatalysis.
Background
According to recent statistics, corneal blindness is the ninth global blinding eye disease. According to the American eye Bank Association, there are about 5000-6000 million patients with corneal graft surgery worldwide, and about 10 ten thousand cases of corneal graft surgery are performed each year, with 13% of cases of graft failure. In China, about 400 thousands of patients with corneal blindness are the second blindness disease in China, and 80% of patients can recover from blindness through allogeneic corneal transplantation. However, the shortage of corneal donors in our country is far from meeting the demand of corneal transplantation. At present, china has nearly 30 eye banks, but the existing cornea bank is continuously exhausted. Including the use of imported corneas, only 5000-6000 cases of cornea transplantation are in China. With the national regulation of imported organ tissues, corneal donors will be severely deficient. In addition, allogenic penetrating corneal transplants have a low success rate in patients receiving severe neovascularization of the cornea, such as severe ocular chemical injury, corneal thermal burns, multiple graft failures, severe dry eye, pemphigus, and stevens-johnson syndrome. Therefore, for these patient populations, keratoprosthesis implantation becomes their ultimate means of reconstructing vision and is also the only hope for saving vision for these patients.
At present, the artificial cornea is mainly composed of a porous peripheral support part and an optical center part. The compatibility between the porous peripheral scaffold part and body tissues plays an important role in stabilizing the optical central part, the optical central part needs higher transparency, proper diopter, antibacterial property and better biocompatibility, and the surface of the optical central part also has stronger resistance to calcium precipitation and cell adhesion. However, the existing artificial cornea optical center has phenomena of calcium precipitation, cell adsorption, protein adsorption and the like after implantation, thereby leading to the formation of front and back proliferation membranes, leading to the deterioration of the light transmittance of the artificial cornea and leading to the ultimate failure of the transplantation operation.
Physical coating, coating and surface grafting of polymers are the main methods for surface modification. The polymer physical coating can only show corresponding performance within a short time after the implantation, and the coating can be gradually peeled off and failed due to complex physiological environment and oxidation in tissues, so that the two methods are not suitable for surface modification of long-term implanted materials. The surface grafting is to connect the graft to the surface of the base material through covalent bond, thus having stable and long-acting effect and being very suitable for surface modification of long-term implant materials.
Free radical polymerization is the earliest studied polymerization reaction for the most widespread industrial use. Compared with other polymerization processes, free radical polymerization has the characteristics of wide monomer source, simple process, low price and abundant products, so that people always pay attention to the free radical polymerization. The disadvantage of free radical polymerization is that the control of the relative molecular mass, molecular mass distribution, sequence structure, and steric structure of the polymer is less than ideal for other polymerization processes. The free radical polymerization process is a polymerization reaction initiated by free radicals to make the chain-extended free radicals continuously extend. The living radical polymerization is one of living polymerization reactions, and has the advantages of controllable molecular weight of the polymer, narrower molecular weight distribution (same chain length), end group functionalization, three-dimensional structure (comb type, star type macromolecule), block copolymer, graft copolymer and the like, so that the living radical polymerization is widely applied to surface modification of materials by scientists in recent years. The initial living controlled radical polymerization includes nitroxide stable radical polymerization, atom transfer radical polymerization and reversible-addition fragmentation chain transfer polymerization. No matter which kind of the active controllable free radical polymerization is thermal initiation polymerization in the early stage, so the reaction temperature of the system is higher (60-150 ℃). In addition, the organic solvent used in the activity controllable free radical polymerization is various and has high toxicity, so that the preparation method is not suitable for the preparation, modification and modification of medical biomaterials.
To compensate for the disadvantages of conventional living controlled radical polymerization, photo-initiated polymerization is a good choice. The use of light not only can solve the problems of the living radical polymerization and open up new possibilities, but also creates opportunities for synthesizing functional polymer materials. At room temperature, light activates dormant species, and the activated dormant species has strong active chemical bonds and can perform living radical polymerization of non-conjugated monomers. Ultraviolet light is the light source adopted at the earliest, and is characterized in that: the activation energy is low, and low-temperature polymerization is easy to realize; in the experiment, pure macromolecules without initiator residues can be obtained; the quantum efficiency is high; the absorption of one photon results in the polymerization of a large number of monomer molecules into macromolecules. However, continuous irradiation causes the temperature of the reaction system to increase due to the high energy of ultraviolet light. In addition, studies have shown that: in the reaction system of ultraviolet photopolymerization, a part of molecules may be decomposed by an excessively high energy of ultraviolet light. Therefore, the development of living controllable free radical polymerization initiated by visible light is increasingly necessary.
Reversible-addition fragmentation chain transfer polymerization has received much attention as a new living controlled radical polymerization. In classical radical polymerization, irreversible chain transfer side reaction is one of the main factors causing uncontrollable polymerization, but when the chain transfer constant and the concentration of the chain transfer agent are large enough, the chain transfer reaction changes from irreversible to reversible, and the polymerization behavior also changes qualitatively from uncontrollable to controllable. Reversible-addition fragmentation chain transfer polymerization the key to successfully achieving controlled polymerization is the discovery of chain transfer agents (dithioesters or trithioesters) with high transfer constants and specific structures. Among the living/controlled radical polymerization systems that have been discovered so far, reversible-addition fragmentation chain transfer polymerization is one of the most industrially promising controlled polymerizations. The polymerization can be carried out at low temperature by combining the photoinitiated reversible-addition fragmentation chain transfer polymerization, and the system has single solvent type, is easy to be clear, and is very suitable for the preparation and surface modification of biomedical materials.
Disclosure of Invention
The invention mainly solves the problems that the artificial cornea optical center can generate calcium precipitation, cell adsorption, protein adsorption and the like after being implanted, and the problems that the traditional reaction steps are complex, the system solvents are various, the reaction temperature is higher and the like. In order to solve the problem, the technical scheme provided by the invention is as follows:
a modifying liquid for an optical center of an artificial cornea, comprising: glycidyl methacrylate, a photocatalyst, a reaction solvent and a chain transfer agent.
Preferably, the photocatalyst is tris (2, 2 '-bipyridyl) ruthenium (II) chloride and/or iridium bis [2- (2, 4-difluorophenyl) -5-trifluoromethylpyridine ] [2-2' -bipyridyl ] hexafluorophosphate.
3. The modifying solution for an optical center of an artificial cornea of claim 1, wherein said reaction solvent is N' N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone and/or tetrahydrofuran.
Preferably, the chain transfer agent is 4-cyanovaleric acid dithiobenzoic acid, isobutyl naphthoate and/or 2-ethylxanthate.
A method for preparing an optical center of a keratoprosthesis, the method comprising the steps of:
(1) Subjecting polyvinyl alcohol particles to a swelling-dissolving process in a mixed solution to obtain uniform viscous fluid to obtain sol;
(2) Pouring the dissolved sol into a mold, and cooling to room temperature to form a primary transparent gel;
(3) The freezing-unfreezing process is circulated, namely the preliminarily molded transparent gel is frozen at the temperature of minus 20 ℃ for 10 hours, then unfrozen at room temperature for 1 hour, and is subjected to 7 cycles;
(4) Demoulding, soaking in deionized water, and replacing the deionized water for multiple times to remove the residual dimethyl sulfoxide solvent to obtain PVA film-shaped hydrogel with high transmittance;
(5) Cutting the prepared film-shaped hydrogel into strips with the size of 10mm multiplied by 20mm by a laser marking machine, and taking wafers with the d approximately equal to 10mm as a modified base material for later use;
(6) Decoration
0.05mmol/L of 0.2-5mL of chain transfer agent, 0.01mmol/L of 0.02-5mL of photocatalyst, 0.01mmol/L of glycidyl methacrylate and 5-15mL of water are dissolved in 10-30mL of reaction solution to prepare modified solution, the modified base material is put into the solution, the solution is screwed down and put into a gas bath constant temperature shaking table, the temperature is set to be 20-50 ℃, the rotating speed is set to be 100-150rpm, a 450-620nm LED lamp is adopted for irradiation for 24 hours, then the modified base material is taken out from a reaction container and is soaked in deionized water for 5 days, and the deionized water is replaced three times every day;
dissolving a polysaccharide compound in an ethanol solution, then putting the modified hydrogel into a reaction container, adding triethylamine, sealing the reaction container, and reacting for 12 hours at 50-60 ℃;
and finally, taking out the modified hydrogel from the reaction vessel, soaking the hydrogel in deionized water for 5 days, and replacing the deionized water three times every day to obtain the modified artificial cornea optical center.
Preferably, the mixed solution in the step (1) is prepared from DMSO and H in a volume ratio of 4 2 O。
Preferably, the size of the mold in step (2) is 80mm × 80mm × 1mm.
Preferably, the wavelength of the irradiation in step (6) is 450 to 460nm,520nm or 620nm.
Preferably, the polysaccharide compound in step (6) is chitin, chitosan and its derivatives and/or chondroitin and its derivatives.
The invention has the advantages that the invention carries out the activity controllable free radical polymerization under the initiation of visible light, so the reaction condition is mild, the reaction is controllable, and the invention is very suitable for the surface functionalization modification of biomedical materials. The polyvinyl alcohol modified by glycidyl methacrylate can be subjected to ring-opening grafting (acidic environment and alkaline environment) with a plurality of substances with hydroxyl and amine groups. The epoxy group is very stable in a room temperature environment, and ring opening phenomenon cannot occur. Therefore, the method is very suitable for surface modification of biomedical materials.
Polysaccharide compounds (chitin and chitosan) are natural polymers with excellent performances such as biological functionality and compatibility, blood compatibility, safety, microbial degradability and the like, are widely concerned by various industries, and have made great progress in application research in various fields such as medicine, food, chemical industry, cosmetics, water treatment, metal extraction and recovery, biochemistry and biomedical engineering and the like. Therefore, ring-opening grafting of the polysaccharide on the epoxy functionalized surface can provide special functions, such as antibacterial property, to the optical central area of the artificial cornea. In addition, because the polysaccharide has degradability, the anti-adhesion performance of the artificial cornea is greatly improved in a long period of time, so that the problems of later-stage calcium precipitation, cell adsorption, protein adsorption and the like are reduced.
Detailed Description
The following substances were prepared:
secondly, the high-transmittance polyvinyl alcohol (PVA) film-shaped hydrogel is prepared by a sol-gel method, and the three-dimensional network crosslinking degree of the PVA film-shaped hydrogel is enhanced by circulating a freezing-thawing process;
in the first step, a certain amount of polyvinyl alcohol particles are mixed in a mixed solution (DMSO: H with a volume ratio of 4 2 O) undergoes a swelling-dissolving process to form uniform viscous fluid (sol state);
secondly, pouring the dissolved sol into a stainless steel mold (80 mm multiplied by 1 mm), and cooling to room temperature to form primary transparent gel;
thirdly, circulating a freezing-unfreezing process, namely freezing the preliminarily molded transparent gel at-20 ℃ for 10 hours, unfreezing the gel at room temperature for 1 hour, and circulating for 7 times;
fourthly, demolding, soaking in deionized water, and replacing the deionized water for multiple times to remove residual dimethyl sulfoxide solvent to obtain PVA film-shaped hydrogel with high transmittance;
fifthly, cutting the prepared membranous hydrogel into a long strip (10 mm multiplied by 20 mm) and a wafer (d is approximately equal to 10 mm) by using a laser marking machine, and taking the long strip and the wafer as a modified base material for later use;
sixthly, modifying the optical center of the artificial cornea
0.05mmol/L of 0.2-5mL of 4-cyanopentanoic acid dithiobenzoic acid, 0.01mmol/L of 0.02-5mL of tris (2, 2 '-bipyridine) ruthenium (II) chloride hexahydrate, 0.01-5mL of glycidyl methacrylate and 5-15mL of water are dissolved in an N' N-dimethylformamide aqueous solution to prepare a modified solution; polyvinyl alcohol hydrogel (10 mm. Times.20 mm) was placed in the modification solution. The reaction vessel was screwed down and placed in a gas bath constant temperature shaking table (150rpm, 20-50 ℃), and a blue (450-460nm, 520nm, 620nm) LED lamp was irradiated for 24 hours, and then the modified hydrogel was taken out from the reaction vessel and soaked in deionized water for 5 days (deionized water was changed three times a day).
Dissolving 2-hydroxypropyl trimethyl ammonium chloride chitosan in ethanol solution, placing the modified hydrogel into a reaction container, adding a certain amount of triethylamine, sealing the reaction container, and reacting at 50-60 ℃ for 12h. Finally, the modified hydrogel was removed from the reaction vessel and soaked in deionized water for 5 days (three changes of deionized water per day).
The anti-adhesion performance prepared by the method is greatly improved, and the problems of later-stage calcium precipitation, cell adsorption, protein adsorption and the like are solved.
Claims (8)
1. A method for preparing an optical center of a keratoprosthesis, comprising the steps of:
(1) Subjecting polyvinyl alcohol particles to a swelling-dissolving process in a mixed solution to obtain uniform viscous fluid to obtain sol;
(2) Pouring the dissolved sol into a mold, and cooling to room temperature to form a primary transparent gel;
(3) The freezing-unfreezing process is circulated, namely the preliminarily molded transparent gel is frozen at the temperature of minus 20 ℃ for 10 hours, then unfrozen at room temperature for 1 hour, and is subjected to 7 cycles;
(4) Demolding, soaking in deionized water, and replacing the deionized water for multiple times to remove residual dimethyl sulfoxide solvent to obtain PVA film-shaped hydrogel with high transmittance;
(5) Cutting the prepared film-shaped hydrogel into strips with the size of 10mm multiplied by 20mm by a laser marking machine, and taking wafers with the d approximately equal to 10mm as a modified base material for later use;
(6) Decoration
0.05mmol/L of 0.2-5mL of chain transfer agent, 0.01mmol/L of 0.02-5mL of photocatalyst, 0.01mmol/L of glycidyl methacrylate and 5-15mL of water are dissolved in 10-30mL of reaction solution to prepare modified solution, the modified base material is put into the solution, the solution is screwed down and put into a gas bath constant temperature shaking table, the temperature is set to be 20-50 ℃, the rotating speed is set to be 100-150rpm, a 450-620nm LED lamp is adopted for irradiation for 24 hours, then the modified base material is taken out from a reaction container and is soaked in deionized water for 5 days, and the deionized water is replaced three times every day;
dissolving a polysaccharide compound in an ethanol solution, then putting the modified hydrogel into a reaction container, adding triethylamine, sealing the reaction container, and reacting for 12 hours at 50-60 ℃;
and finally, taking out the modified hydrogel from the reaction vessel, soaking the hydrogel in deionized water for 5 days, and replacing the deionized water three times every day to obtain the modified artificial cornea optical center.
2. The method for preparing an optical center of a keratoprosthesis according to claim 1, wherein the mixed solution of the step (1) is prepared from DMSO H in a volume ratio of 4 2 O。
3. The method of claim 1, wherein the mold in step (2) has dimensions of 80mm x 1mm.
4. The method of claim 1, wherein the irradiation wavelength in step (6) is 450-460nm,520nm or 620nm.
5. The method of claim 1, wherein the polysaccharide compound in step (6) is chitin, chitosan and its derivatives and/or chondroitin and its derivatives.
6. The method of claim 1, wherein the photocatalyst is tris (2, 2 '-bipyridyl) ruthenium (II) chloride and/or bis [2- (2, 4-difluorophenyl) -5-trifluoromethylpyridine ] [2-2' -bipyridyl ] iridium hexafluorophosphate.
7. The method of claim 1, wherein the reaction solvent is N' N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, and/or tetrahydrofuran.
8. The method of claim 1, wherein the chain transfer agent is 4-cyanopentanoic acid dithiobenzoate, isobutylnaphthoate and/or 2-ethylxanthate.
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