Study On The Preparation And Properties Of Bacterial Cellulose Composites For Artificial Cornea

There are probably more than 10 million people worldwide suffering from blindness of corneal origin, and their visual recovery relies heavily on the successful grafting of donor corneal tissue. However, the only alternative for restoring vision appears to be the prosthokeratoplasty for the patients who are unlikely to benefit from penetrating keratoplasty. At present artificial cornea materials including optical centre and porous skirts, but most artificial corneas failed because of poor interaction between the artificial implant and host conrea, and poor attachment of the transparent center to the skirt. Moreover, artificial cornea materials (such as PHEMA, PVA and silicone gels) usually have some problems, such as poor mechanical properties and biocompatibility. Bacterial cellulose (BC) has many advantages and can be applied as artificial cornea material, duo to its fine nanofiber network, biocompatibility, high water holding capacity and high tensile strength. However, it has some defects for artificial cornea, such as low transparency and easy bacterial infection. In this paper, BC/PVA and BC/PHEMA composites were prepared to overcome these problems. Water content, transmittance, structure, thermal stability and mechanical properties of the composites were investigated by XRD, FTIR, TG and DSC analyses.In this work, BC/PVA and BC/PHEMA transparent composites were prepared by freeze-thaw and bulk free-radical polymerization, respectively. The results showed that the water content of BC/PVA composites was as high as 73% which was close to that of nature cornea (78%). However, the water content of BC/PHEMA composites was lower (about 37%). Both of the two composites had good transmittances to the visible light, meanwhile had certain absorption to the ultraviolet radiation. The transmittance of BC/PVA composites was between 80% and 88%, while transmittance of BC/PVA composites reached above 90%. The results of TGA and DSC showed that the thermal degradation temperature of BC/PVA and BC/PHEMA composites was dramatically improved compared with the pure PVA and PHEMA. As BC mass fraction increased, the two composites showed an increase in thermal degradation temperature.The results of mechanical properties testing of the composites showed that Young's modulus and tensile strength were dramatically improved in comparison to that of matrix materials, and increased with the BC mass fraction. However, the elongation at break decreased.Optical properties, thermal stabilities and mechanical properties of the two composites could meet the requirements of artificial cornea materials. However, water content and transmittance of BC/PVA composites were better when compared to BC/PHEMA composites. Evidently, the overall properties of BC/PVA composites were superior to BC/PHEMA composites.