Preliminary Study On Biodegradable Anastomosis Ring Silk Fibroin/PLGA Degradation Properties And Biocompatibility

Purpose1. Implement vivo and vitro degradation tests for composite sample with different proportions of silk fibroin and PLGA and prepare silk fibroin and PLGA composite which conforms to degradation time requirements of device design in the research.2. Implement cytotoxicity test for composite sample with different proportions of silk fibroin and PLGA composite, evaluate its histocompatibility and finally find a kind of material proportions with the best safety and reliability.Method1. Preparation of silk fibroin and PLGA composite. Make silk fibroin and PLGA powder material dissolved in chloroform according to different proportions (1:5,1:10, and1:20) and mix to paste. Then, lay it on glass plate naturally. After drying, cut it to composite plate with size of1.5cm×1.5cm for reserve of drying and refrigeration.2. Vitro static degradation test of material. Put membrane of silk fibroin and PLGA composite in artificial simulation intestinal juice and keep37℃degradation temperature in incubator. Replace artificial intestinal juice regularly in each week. Take out of the sample in the first, second, third, fourth, sixth and eighth weeks and dry to constant weight. Then, calculate weight loss rate and evaluate its degradation condition.3. Biocompatibility evaluation of silk fibroin and PLGA composite. Hemolysis test and micronucleus test of maceration extract of fibroin and PLGA composite are adopted. Determine absorbance after hemolysis by spectrophotometry and implement material toxity grading, calculation of body temperature change condition and micronucleus rate of SD rats, incision tissue HE dyeing of composite membrane, Masson dyeing and hydroxyproline determination so as to evaluate biocompatibility of silk fibroin and PLGA composite.Results1. Silk fibroin and PLGA composite becomes brittle and fragile with degradation. Furthermore, its weight loses gradually. The fastest degradation speed is in the second-fourth weeks. Degradation is about68%. Later on, degradation becomes slowly;2. Hemolysis ratio and micronucleus rate of material on biocompatibility are all<5%.3. Animal experiment preliminarily indicates:①HE staining was visible around the large amount of inflammatory cell infiltration, the proportion of Yunnan Baiyao mixed material PLGA group than in control group were less positive rubber;②The ratio of mixed material group has significant difference at the same time and rubber group (P<0.05), there are significant differences at the same time comparison between the ratio of material group (P<0.05), the ratio of material group were significantly different in different time (P<0.05);③Masson staining of collagen fiber cut blue green, red muscle fibers and cellulose.In7days we can see the inflammatory cell accumulation, fibroblast proliferation, collagen deposition of collagen in small, slender, sparsely.14days to see large incision collagen deposition, thick, dense collagen.Conclusion1. Different degradation speed of composite can be achieved through adjusting proportion between silk fibroin and PLGA material so as to meet different application requirements.2. Silk fibroin and PLGA composite is a kind of biodegradable materials which does not consist of heat source material without hemolysis. It cannot lead to malformation. Besides, it has good biocompatibility and it is safe and nontoxic; furthermore, it can reduce inflammatory reaction of wound and promote wound healing.