Study On Drug Delivery Of Silk Fibroin PH Sensitive Microneedles

Silk fibroin is widely used in biomedical fields such as tissue engineering,porous materials,and drug sustained release due to its good biocompatibility,biodegradability,controlled degradation rate and unique physicochemical properties.In this paper,silk fibroin was blended with N,N-dimethylaminoethyl methacrylate(DMA)and chitosan(CS),respectively,using hydrogen peroxide(H2O2)-horseradish peroxidase(HRP).Three pH-sensitive hydrogels were prepared by two cross-linking systems of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride(EDC).(1)H2O2-HRP system Adding to the blended SF/PDMA,H2O2-HRP generates free radicals to initiate polymerization of DMA monomer to form PDMA and silk fibroin macromolecular entanglement to form an interpenetrating network structure hydrogel;(2)H2O2-HRP system Adding to the SF/CS blending solution,the generated free radicals induce partial crosslinking of the amino acids in the silk fibroin molecule with the amino group in the chitosan to form a hydrogel;(3)adding EDC to the SF/CS blending solution The carboxyl group(-COOH)in the macromolecular amino acid of EDC-activated silk fibroin reacts with the amino group in chitosan to form a hydrogel,and the aggregate structure,surface morphology,mechanics and after drying of the three hydrogels The pH swellability was characterized.Studies have shown that the three hydrogels have a large amount of random crimp compression of 80%and a resilience of up to about 90%.After drying with good pH sensitive swelling behavior.The hydrogel can be used for tissue engineering repair and sustained drug release.On this basis,a hydrogel prepared by cross-linking silk fibroin/chitosan with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride(EDC)was selected.It is prepared into a pH-sensitive microneedle,and insulin labeled with fluorescein isothiocyanate I(FITC)is used as a model drug,and the transdermal drug delivery experiment is carried out by simulating human skin of rabbit skin to explore the drug of the microneedle.The law of release shows that the microneedle has good mechanical properties and can penetrate the rabbit skin well and maintain its original shape.Transdermal delivery data indicate that the microneedles have good pH sensitivity and are capable of different drug release rates in buffer solutions of different pH values,with rapid release of the drug at low pH conditions,as the pH value raised,the drug release rate is gradually reduced.When the pH value of the isoelectric point of the microneedle is reached,the drug release rate is the lowest at this time,and the drug release rate is accelerated after the pH value of the isoelectric point is exceeded.The study provides a new approach to the treatment of diabetes.