CN1660450A - Bioactive artificial cornea and preparation method thereof - Google Patents

Abstract

A bioactive artificial cornea is composed of optical center and peripheral scaffold. Its preparing process includes proportionally dissolving high-molecular polyvinyl alcohol is solvent, proportionally adding bioactive calcium salt, stirring, proportionally mixing it with pore-forming agent, moulding to obtain a hollow cylindrical scaffold, preparing optical center in the scaffold, and removing residual solvent, pore-forming agent and impurities in deionized water.

Description

Bioactive artificial cornea and preparation method thereof

Technical field:

The invention relates to the field of biomedical materials, in particular to an artificial cornea for corneal transplantation and replacement and a preparation method thereof.

Background technique:

The artificial cornea is a clinical need to replace the biological cornea to save blindness due to corneal disease. In the case of multiple corneal transplant failures, alkali burns, lack of tears, severe corneal vascularization, etc., artificial corneas are the only hope to finally save and restore vision. Most of the existing artificial corneas are penetrating artificial corneas, which are composed of an optical center and a peripheral bracket. The optical center is made of optical material with good light transmission, which restores the optical channel of the eye; the peripheral stent part plays a key role in providing a watertight joint with the host tissue and supporting the stability of the artificial cornea. Most of the complications of artificial cornea, such as drainage, aqueous humor leakage, formation of artificial corneal posterior membrane, endophthalmitis, etc., are not well connected with the peripheral part of the artificial cornea and the host corneal tissue, and thus cannot provide effective support and fixation, etc. function related. The joint between the peripheral stent part of the artificial cornea and the host corneal tissue should be a functional and biological joint rather than a simple mechanical joint.

Bioactive phosphate is very similar to the inorganic components in natural hard tissues, has good biocompatibility, can induce cell growth and division, and can grow into soft tissues such as fibrovascular, and has been widely used in orthopedics and dentistry. However, bioactive phosphate has low strength, high brittleness, is not easy to process, and is difficult to withstand the general external force during and after surgery.

The purpose of the present invention is to provide a bioactive artificial cornea with simple manufacturing process, easy molding, good biocompatibility and high strength and its preparation method.

The present invention is achieved like this:

The bioactive artificial cornea of the present invention includes an optical center and a peripheral frame, and the peripheral frame is made of the following components and amounts: % by weight

  Biologically active calcium salt         0.1-20

  High Molecular Polyvinyl Alcohol           1-15

Solvent 75-98

After the polymer polyvinyl alcohol is dissolved in the solvent, add bioactive calcium salt and mix uniformly to obtain a mixed solution, then add a porogen to obtain a mixture, mixed solution: porogen = 1: (0.5-2), weight ratio, and place the mixture After the mold is formed into a hollow cylindrical peripheral bracket, the optical center is formed in the inner cavity of the peripheral bracket, and the residual solvent, porogen and other impurities are removed in deionized water.

After the mixture is put into the mold, it is frozen at minus 10-40°C.

The biologically active calcium salt is at least one of hydroxyapatite, nano-hydroxyapatite, tricalcium phosphate, and tetracalcium phosphate. When there are multiple kinds of inorganic substances, the inorganic substances are in any weight ratio.

The solvent is a solution of water and dimethyl sulfoxide or glycerol, the weight % of water in the solution is <30, the solvent can also be at least one of dimethyl sulfoxide and glycerin, and when there are two kinds, it can be any weight Compare.

The dosage of bioactive calcium salt is 10%, the dosage of high molecular weight polyvinyl alcohol is 10%, the dosage of solvent is 80%, fusion solution: porogen=1:1, porogen is sodium chloride.

The porogen is at least one of sodium chloride, potassium chloride, sodium bicarbonate, and sucrose, and when there are more than one, it is in any weight ratio.

The preparation method of artificial cornea of the present invention comprises the steps:

1) Prepare a hollow cylindrical peripheral stent,

2) Inject the polymer solution into the lumen of the surrounding stent for cross-linking to form a blank,

3) Cut the cured artificial cornea blank into the required size to make a semi-finished product,

4) Soak the semi-finished product in deionized water to remove residual solvent, porogen and other impurities to obtain a finished product.

8. The method for preparing an artificial cornea according to claim 7, characterized in that said polymer solution is mixed with initiator, cross-linking agent, and polymer monomers to form a solution, or is a polyvinyl alcohol solution, The polymer monomer is one of methyl methacrylate, 2-hydroxyethyl methacrylate and methacrylic acid.

The invention overcomes the disadvantages of the existing artificial cornea, and provides an artificial cornea with good biocompatibility with eye tissue, good performance and capable of biological healing with the cornea and a preparation method thereof. Artificial corneal stents are mostly porous materials that facilitate tissue ingrowth, but many existing stent materials do not have biological activity. The composite porous material of macromolecular polyvinyl alcohol and biologically active phosphorus-calcium salt has the activity of phosphorus-calcium salt, and its pores are through holes (as shown in Figure 1). Bioactive phosphate/polymer composite artificial corneal peripheral scaffold material can improve the shortcomings of bioactive phosphate, such as too hard material, too thick material, mechanical top pressure and difficult processing. This composite material utilizes the good biocompatibility of bioactive phosphate and the property of forming a strong chemical bond on the interface of soft tissue to improve the bonding between the artificial corneal stent and the host corneal tissue.

Invention content:

In order to further confirm the good biocompatibility of the artificial cornea and the ability to produce biological healing with the cornea, animal experiments were carried out. Slit lamp examination showed that the postoperative artificial cornea was fixed in the lamellar capsular bag, and no material discharge or infection was found. Within 3 days after surgery, eyelid margins were red and swollen, conjunctival hyperemia, tearing, and secretions, which basically disappeared after 1 week. On 6 days after surgery, superficial new blood vessels appeared in the corneal limbus, mostly in the form of burrs from the insertion of the superior rectus muscle to the center of the cornea Afterwards, new blood vessels grew in other directions. One month after operation, most of the new blood vessels invaded the center of the cornea. At three months after operation, the growth of new blood vessels reached its peak. Six months after operation, a large number of thinning remained in the center of the corneal bed. Most of the new blood vessels are located in the deep matrix (Figure 2, 3).

One month after the operation, fibroblasts, new blood vessels and a small amount of inflammatory cells grew into the pores of the skirt material, accompanied by a small amount of collagen formation. The skirt material is closely adhered to the corneal stroma on the front, back and outside without gaps. At 3 months after operation, all pores in the marginal scaffold material were filled with new tissue, mainly collagen cells and new blood vessels. The scaffold material is near the central optical part, and collagen fiber cells can be seen in the pores. The corneal epithelium and endothelium remained intact (Figure 4). The adhesion of corneal tissue in the central optical part was poor, and there was no adhesion of epithelial cells or inflammatory cells.

The analysis of animal experiment results shows that the artificial cornea of the present invention has good biocompatibility, a large amount of peripheral corneal tissue grows into the pores of the scaffold material, and no complications such as infection, dissolution, aqueous humor leakage or prolapse are found after implantation. The research results show that the corneal epithelium and endothelium remain intact, indicating that the artificial cornea does not hinder the nutrient supply and transportation of the normal cornea. The artificial corneal porous scaffold of the present invention not only has good histocompatibility and good biological activity, can promote the bioembedding of new blood vessels and eye tissues, but also can inhibit the growth of abnormal corneal epithelial cells and endothelial cells, so that in To a certain extent, the occurrence of postoperative complications is reduced. The artificial cornea of the present invention is beneficial to improve the biological bonding between the artificial corneal stent part and the host corneal tissue, and is beneficial to the long-term retention of the artificial cornea in the body. The artificial cornea of the present invention is beneficial to improve the biologically firm joint between the artificial corneal support part and the host corneal tissue, and simultaneously solves the joint problem between the optical center and the surrounding support, and has important clinical application prospects.

Description of drawings:

Fig. 1 is the scanning electron micrograph of peripheral support of the present invention

Figure 2 shows that a large number of new blood vessels grow into the center of the cornea one month after the artificial cornea was implanted into the interlamellar layer of the rabbit cornea.

Figure 3 shows that 3 months after the artificial cornea was implanted into the interlamellar layer of the rabbit cornea, a large number of new preparation tubes grew into the center of the cornea, and the edge of the stent was visible without exposure.

Figure 4 is a tissue slice of the surrounding scaffold 3 months after implantation, the pores of the scaffold material were filled with collagen cells and new blood vessels.

Detailed ways:

Example 1:

1. Dissolve 10g of high-molecular polyvinyl alcohol in 80g of dimethyl sulfoxide, add 10g of tricalcium phosphate and mix well, then add 100g of sodium chloride particles, stir well, pour the mixture into a cylindrical mold, and get Perimeter bracket.

2. Inject a mixed solution of methyl methacrylate, divinyl glycol, and azobisisoheptyl cyanide into the hollow cylinder of the surrounding bracket for cross-linking;

3. Take out the formed artificial cornea blank and cut it into the size of the artificial cornea;

4. The product is immersed in deionized water, and the deionized water is replaced every 8 hours at room temperature, and taken out after 72 hours. At this time, the porogen in the composite material is dissolved to form a porous structure, and the desired artificial cornea is obtained.

Example 2:

1. Dissolve 5g of high-molecular polyvinyl alcohol in 80g of glycerin, add 15g of tetracalcium phosphate and mix well, then add 200g of potassium chloride particles, stir well, pour the mixture into a cylindrical mold, and form a peripheral bracket.

2. Inject a polyvinyl alcohol solution with a concentration of 10% by weight into the hollow cylinder for cross-linking;

3. Take out the formed artificial cornea blank and cut it into the size of the artificial cornea;

4. The product is immersed in deionized water, and the deionized water is replaced every 8 hours at room temperature, and taken out after 72 hours. At this time, the porogen in the composite material is dissolved to form a porous structure, and the desired artificial cornea is obtained.

Example 3:

1. Dissolve 15g of high-molecular polyvinyl alcohol in 20g of water and 55g of dimethyl sulfoxide, add 10g of nano-hydroxyapatite and mix well, then add 50g of sucrose, stir well, and pour the mixture into a cylindrical mold to make a peripheral stand.

2. Inject a mixed solution of 2-hydroxyethyl methacrylate, N,N-methylenebisacrylamide, and azobisisobutylcyanide into the hollow cylinder for crosslinking;

3. Take out the formed artificial cornea blank and cut it into the size of the artificial cornea;

4. The product is immersed in deionized water, and the deionized water is replaced every 8 hours at room temperature, and taken out after 72 hours. At this time, the porogen in the composite material is dissolved to form a porous structure, and the desired artificial cornea is obtained.

Example 4:

1. Dissolve 1g of high-molecular polyvinyl alcohol in a solution of 68g of dimethyl sulfoxide and 30g of water, add 1g of mixed particles of hydroxyapatite and tricalcium phosphate in any mixing ratio, mix well and add 120g of sodium bicarbonate , and after mixing well, pour the mixture into molds to make perimeter supports.

2. Inject a mixed solution of methacrylic acid, N,N-methylene bisacrylamide, and lauryl peroxide into the hollow cylinder for crosslinking;

3. Take out the formed artificial cornea blank and cut it into the size of the artificial cornea;

4. The product is immersed in deionized water, and the deionized water is replaced every 8 hours at room temperature, and taken out after 72 hours. At this time, the porogen in the composite material is dissolved to form a porous structure, and the desired artificial cornea is obtained.

Example 5:

Dissolve 13g of high-molecular polyvinyl alcohol in 86.9g of glycerin, add 0.1g of phosphoapatite and mix evenly, then add 80g of sodium chloride and stir, then pour the mixture into a mold to make a peripheral bracket.

Its steps are the same as in Example 1.

Claims (8)

1. Bioactive artificial cornea, including optical center and peripheral support, characterized in that the peripheral support is made of the following components and amounts: % by weight   Biologically active calcium salt     High Molecular Polyvinyl Alcohol                                           Solvent 75-98 After the polymer polyvinyl alcohol is dissolved in the solvent, add bioactive calcium salt and mix uniformly to obtain a mixed solution, then add a porogen to obtain a mixture, mixed solution: porogen = 1: (0.5-2), weight ratio, and place the mixture After the mold is formed into a hollow cylindrical peripheral bracket, the optical center is formed in the inner cavity of the peripheral bracket, and the residual solvent, porogen and other impurities are removed in deionized water. 2. The artificial cornea according to claim 1, characterized in that the mixture is put into the mold and frozen at minus 10-40°C for molding. 3. The artificial cornea according to claim 1, characterized in that said bioactive calcium salt is at least one of hydroxyapatite, nano-hydroxyapatite, tricalcium phosphate, and tetracalcium phosphate. When there are multiple types, the inorganic substances may be in any weight ratio. 4. The artificial cornea according to claim 1, characterized in that said solvent is a solution of water and dimethyl sulfoxide or glycerol, the weight % of water in the solution is <30, and the solvent can also be dimethyl sulfoxide At least one of sulfone and glycerin, when there are two kinds, may be in any weight ratio. 5. The artificial cornea according to claim 1, characterized in that the amount of bioactive calcium salt is 10%, the amount of high molecular polyvinyl alcohol is 10%, the amount of solvent is 80%, fusion solution: porogen =1:1, the porogen is sodium chloride. 6. The artificial cornea according to claim 1, characterized in that said porogen is at least one of sodium chloride, potassium chloride, sodium bicarbonate, and sucrose, and when there are more than one, it can be any weight Compare. 7. The method for preparing an artificial cornea according to claim 1, characterized in that it comprises the following steps: 1) Prepare a hollow cylindrical peripheral stent, 2) Inject the polymer solution into the lumen of the surrounding stent for cross-linking to form a blank, 3) Cut the cured artificial cornea blank into the required size to make a semi-finished product, 4) Soak the semi-finished product in deionized water to remove residual solvent, porogen and other impurities to obtain a finished product. 8. The method for preparing an artificial cornea according to claim 7, characterized in that said polymer solution is mixed with initiator, cross-linking agent, and polymer monomers to form a solution, or is a polyvinyl alcohol solution, The polymer monomer is one of methyl methacrylate, 2-hydroxyethyl methacrylate and methacrylic acid.

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