Laser Processing And Bioactive Surface Construction Of A Novel One-piece Pattern Artificial Cornea

Corneal diseases are common and frequently-occurring diseases, the blind rate of which has ranked the second place according to the results of epidemiology survey. Approximately 20% of these patients cannot recover their visual through the successful grafting of donor corneal tissue. Inaddtion, the insufficient supply of donor organs and graft immune rejection are remaining limit factors. The only desirable alternative to donor graft transplantation is artificial cornea. At present, one-piece pattern and hydrophilic hydrogel are both adopted in the main artificial corneal of the world. However, the hydrogel's inherent low mechanical strength and poor integration often lead to seriously complications and high extrusion rate, which limits its application.In this study, the mechanical property of HEMA is improved firstly by co-polymerized with MMA in with a series of MMA contents. After studying the properties of p (HEMA-MMA) copolymer with different MMA content, the p (HEMA-MMA) copolymer with optimal MMA content is choosed for the artificial cornea bulk materials. Contact lens processing lathe and CO2 laser are introduced to precisely lathe the artificial cornea embryos according to the design parameters and prepare run-through type porous skirt, respectively. This is the first try to import the contact lens processing lathe and CO2 laser to the field of artificial cornea, hoping to find an easy, rapid and cheap way to mold artificial cornea. Then, type-I collagen and bFGF are immobilized onto the "skirt" surface by grafting and coating methods, collagen-grafted layer was formed firstly, and then the collagen and bFGF mixed-layer was subsequently coated onto the grafted layer, the novel hydrogel Col/bFGF-p(HEMA-MMA) is prepared. The stability of the coating layers is studied under different PH values. The cytotoxicity of Col/bFGF-p(HEMA-MMA) is evaluated by cell adhesion and MTT assay. To further explore the prospect of this novel hydrogel as a "skirt" material of artificial cornea, the adhesion rate of keratocytes cultured on Col/bFGF-p (HEMA-MMA) is obtained. The morphology, ultrastructure and biomechanical properties changes of keratocytes cultured on modified hydrogel are studied by AFM. From these changes, we could analyze the effect of material on the physiological property of cell, such as, proliferation and differentiation. Then we also could speculate the cytotoxicity of Col/bFGF-p(HEMA-MMA) to the host tissue and forecast the prospect of Col/bFGF-p(HEMA-MMA) for a "skirt" materials. The results show that the p (HEMA-MMA) hydrogel have a best perform when MMA content is 10%, which could meet the requirement of artificial cornea materials. The artificial cornea embryos molded by contact lens processing lathe and CO2 laser show a smooth and transparent appearance. This demonstrates that this molding method may be an effective, rapid way. The "skirt" material surface compose a two-layer structure coatings, which introduced by grafting and coating methods. Type-I collagen and bFGF are both immobilized onto the polymer surface, and the coating layers have a good stability under body-like environment (PH=7.3-7.4). FTIR, XPS and AFM confirm the successful preparation of Col/bFGF-p(HEMA-MMA). Cell adhesion assay show the number and proliferation rate of human skin fibroblast cells (HSFC) cultured on Col/bFGF-poly (HEMA-MMA) are higher than the other groups. This suggests that the Col/bFGF-poly (HEMA-MMA) could promote the adhesion, proliferation and differentiation of cell. The results of MTT also show that Col/bFGF-poly (HEMA-MMA) has a lower extraction toxicity and better cytocompatibility. Furthermore, the modified membranes have higher cell adhesion rate (nearly 90%) of keratocytes than the unmodified group (down to 60%). AFM reveals that the cell cultured on modified materials exhibit a fully, completely elongated and presents spindle-shape morphology. The study of ultrastructure and biomechanical properties of cell indicate that the cell cultured on modified film is in a better state. These suggest that the modified material may have a good integration with host tissue.