Preparation And Properties Research Of PVA/SF/n-HA Porous Composite Hydrogel

Silk fibroin?SF?,a well-known natural protein from the silkworm?Bombyx mori?has gradually perceived for its remarkable mechanical properties,easy handling,excellent biocompatibility and controllble biodegradability,etc.Artificial cornea,which mainly consist of skrit bracket and optical center,is made of heterogeneous forming material for implantation in patients with ocular replace cloudy cornea tissue of the device.However,most currently artificial corneas are rejected because of poor biocompatibility,corneal prolapse,imflammation and other complications.How to improve the mechanical properties of scaffolds and its biocompatibility with the corneal tissue serving as artificial cornea has been the main research field.Recent studies by several research groups have demonstrated that hydrogels and membranes prepared from silk fibroin support the cultivation of human limbal epithelial cells and corneal endothelial cells and thus display significant potential as artificial cornea scaffolds.Porous polyvinyl alcohol?PVA?/silk fibroin?SF?/nano-hydroxyapatite?n-HA?composite hydrogels were prepared via the physical cross-linking and chemcial cross-linking.The properties and biocompatibility were tested.The main results are summarized in below:1.Silk fibers were obtained with different degumming process from natural silk,and silk fibroin powders were prepared after regenerating,dialysis and freeze-drying.The process was studied and improved by the analysis of degumming rate,concent of silk fibroin solution,scanning electron microscope?SEM?and nano-laser particle size.With the reduce of Na₂CO₃content by improved degumming process,the degumming rate of the three degumming was reduced to 31.73%,and the surface of silk fibroin fibers were smooth and complete.So after improved degumming process,it could ensure the degumming effect and reduce the damage to the surface of silk fibroin.The average particle size of silk fibroin in aqueous solution was 5.1 nm,and the average relative molecular mass was approximately 39.9 kDa.2.Porous PVA/SF/n-HA composite hydrogels were prepared by freezing-thawing and particle-induced pore method.Through the measurement of moisture content,mechanical tensile test,FT-IR,XRD,SEM,and TG analysis,the structure,morphology and mechanical properties of composite hydrogels were studied respectively.The results showed that each component material was successfully compounded into the hydrogel,and the composite hydrogels had good thermal stability.With the increase of SF content,the water content of composite hydrogels gradually increased from 65%to 85%,the tensile strength was 0.38-1.04 MPa,while the breaking elongation was slightly reduced.With freezing-thawing physical crosslinks at 6 times,the composite hydrogels formed the optimally three-dimensional network structures.3.Porous PVA/SF/n-HA composite hydrogels were prepared by chemical-physical crosslinking with genipin?GP?,particle-induced pore and emulsified foaming method,and the properties and surface morphology were studied.The results showed that With the GP content increasing,the structural regularity of PVA/SF/n-HA composite hydrogels was enhanced slightly.The degradation rate was greatly slowed down,and the thermal stability was improved.The moisture content was slightly decreased and all over 70%.the tensile strength was increased to some extent,while the elongation at break was decreased.Compared with the emulsified foaming method,the porosity structure obtained by the particle-induced pore method was more uniform and the porosity size was more controllable.The stability of the composite hydrogels in phosphate?PBS?buffer and protease XIV solution was improved.The mass residue was maintained at more than 97.04%in PBS solution after 28 days,and the three-dimensional porosity structure of composite hydrogels was still maintained.4.Human corneal fibroblusts?HCFs?were used to test the cells cytotoxic of the PVA/SF/n-HA composite hydrogels with different content of genipin by CCK-8 assay.Based on confocal laser scanning microscope?CLSM?,SEM,and CCK-8 assay,HCFs had individually good adhesion and proliferation on PVA/n-HA/SF composite hydrogels.HCFs proliferated and grew into the pores of composite hydrogels.The results of biocompatibility experiments of composite hydrogels showed that it was no acute toxicity,in vitro cytotoxicity was 0 or 1 grade.Overall,PVA/n-HA/SF composite hydrogel was a qualified medical material which conformed to the national standard,belongs to the qualified medical material.Proper crosslinking with GP was beneficial for cell adhesion and proliferation on scaffold materials.