Research On Insulin-loaded Silk Fibroin Microneedles As Sustained Release System

Microneedle is a relatively novel transdermal drug delivery method.In recent years,extensive research on microneedles has provided a new Possibility for the biological application of silk fibroin.Insulin remains the most effective treatment for type 1 diabetes,but too frequent injections can cause pain and even resistance.In this paper,silk fibroin was used as the microneedle substrate,and its partial crystallization was promoted by adding proline to adjust the microneedle release rate,and a drug-loaded microneedle with controlled release was obtained.The proline/silk fibroin solid microneedle has enough stratum coneum to pierce the skin.The silk fibroin added with proline mainly forms a SilkⅠ type crystal structure,when the blending ratio is 0.5/10,1/10.There is no phase separation at 2/10,and different degrees of swelling can be obtained with different proline content.The SEM image shows that the microneedle after swelling forms micropores,and the pore size increases with the increase of swelling degree.On this basis,in order to explore the relationship between the degree of swelling and the release of silk fibroin microneedle,the In vitro release study was carried out.The results show that the release rate of insulin gradually increased with the increase of swelling degree,and it can sustain release for 52 hours.The addition of proline reduces the release rate of silk fibroin and controls it in a suitable range,effectively achieving the controlled release for the insulin.In order to explore the relationship of drug release between blood supply and silk fibroin microneedle,dissolved microneedle and insoluble microneedle were used for drug release comparison.The results show that the dissolved microneedle releasing quickly under high blood supply,and the release rate was slow under low blood supply.However,there was no significant difference in the release of insoluble microneedle under different blood supply.In order to explore the relationship between the drug-loaded form of microneedle and the silk fibroin microneedle releasing rate,a high-loaded hollow microneedle was successfully prepared,and its surface morphology,the failure strength and the penetration performance were studied.The results show that the drug loading of the hollow microneedles is about 5 times that of the solid blended microneedles.In the In vitro drug release,the cumulative release amount of the hollow microneedles is significantly higher than that of the blended solid microneedles.