Preparation Of Genipin Crosslinked Gelatin Hydrogel And Its Effectiveness Evaluation As Nano Antibacterial Drug Carrier

Objective: To make a new dressing by gelatin as main material, genipin as crosslinker,loading with AgSD nanocrystal, test its physicochemical properties, in vitro antibacterial properties and in vivo enhancing would healing abilities. Methods:To make gelatin hydrogel in different crosslink degree with different dosage of genipin. Observe L929 cells spreading situation on them after cultured; Study the biocompatibility of gel extraction by MTT assay; The swelling ratio will be calculated of different crosslinking degree gels in PBS of different PH within 24h; Observe the microstructure with SEM. To establish analysis method of AgSD by UPLC; To prepare AgSD-nanocrystal by ball milling and observe the microstructure with TEM; Compare its solubility in 6h with AgSD bulk. To prepare AgSD-nanocrystal-loaded gelatin hydrogel of different crosslink degree, study its solubility change comparing with bulk-loaded gelatin and discuss their dissolution mechanism; Observe the microstructure with SEM; Evaluate its stability in 6 weeks by the change of dissolution curve and microstructure. Study the inhibition zone diameters of sensitive strains, biocompatibility, MIC and MBC on AgSD-nanocrystal suspension to AgSD-bulk suspension. To prepare deep II degree scald mice model with aureus infection,calculate healing index after 3 weeks of treatment by drug-loaded hydrogel dressing; The collagen deposition was studied after sirius red staining; Pathological manifestations was observed after H&E staining. Results: L929 cells tend to spread well as crosslink degree of gels increasing; The swelling property decreased along with gels's crosslink degree getting increased and PH of PBS getting higher, and all groups of hydrogel have good biocompatibility. UPLC method is accurate and efficient for the determination of AgSD;The mean particle size of AgSD-nanocrystal is about 267.8nm after comminuted, lamellar crystal is presented in TEM; The dissolution is about 19% in AgSD-bulk suspension within 6h while more than 80% in AgSD-nanocrystal suspension within only 10 min; But stability experiment reveals that the dissolution of AgSD-nanocrystal drops down to 56% from 92%within 6 weeks. In bacteriostatic ring test and MIC, MBC test, the antibacterial performance of AgSD-nanocrystal suspension groups are significantly improved than AgSD-bulk suspension groups; Cytotoxicity test shows that AgSD-nanocrystal suspension has greater cytotoxicity than AgSD-bulk, but when the former loaded into gelapin hydrogel,the cytotoxicity will be much lower than its in suspension(P<0.05), and the same result when compare with AgSD cream(P<0.05). Significant increase (P< 0.05) occured in healing index since the second week in nanocrystal gel group compared with staph group,cream group and bulk powder gel group in wound-healing experiment. And compared with those control groups, nanocrystal gel group have more content of type I collagen and total collagen, and higher pathology scores. Conclusion: AgSD-nanocrystal loaded gelapin hydrogel have good dissolution, stability, biocompatibility and swelling property, have great advantages in vitro antibacterial properties and in vivo enhancing would healing abilities. It is a dressing with much potential and worthy of further study.