Transdermal Release Of Insulin Loaded Silk Fibroin Microneedles

In order to reduce the pain caused by subcutaneous injection,the microneedle is a new drug delivery method which is widely concerned.In this paper,silk fibroin was used as the base material,which added to proline to make swelling modification,then insulin loaded microneedles prepared for treating type I diabetes.In this paper,composite microneedles and swelling microneedles with soluble tip and swelling base were prepared and their properties were explored.According to the result,fibroin-based microneedles as main body had sufficiently mechanical properties to puncture the epidermis and to achieve drug release.The reduce of dissolution rate was result of that proline made silk fibroin transforms into silk I crystal structure.In term of drug loaded microneedles’ studying at the release rule,in-vitro release tests were operated.As the result,the rate of dissolution release was faster than that of swelling release.In addition,there was more amount of release on compound microneedles in the early stage of drug release,then the speed of release gradually slowed down with the dissolution of needle tip.Insulin in the swelling microneedles released gradually with the swelling process,meanwhile,it last for a long time.Moreover,the stationary test showed that insulin,which was stored in microneedles,maintained more than 90%of activity in room temperature after 30 days.On the basis of in vitro experiment,the model of type 1 diabetes mellitus was established on rats.It studies the drug-loaded microneedles in respect of the hypoglycemic effect and the change of serum insulin concentration inside rats.The outcome illustrated that two types of microneedles caused the hypoglycemic effect,in addition,efficacy maintained longer time than traditional administering inj ection.Furthermore,the released time of compound microneedles was shorter while swelling microneedles was better on the sustained release effect.Compared with the administering injection,drug delivering by microneedles can keep more time and relieve the pain of injection,at the same time,bioavailability can reach over 90%.The law of in vivo release is similar to its in vitro release,but in vivo release has faster rate on releasing insulin.It is likely that the diffusion rate of insulin is affected by the blood flow velocity and systemic circulation,consequently,the release rate is influenced.Moreover,it is not easy to leave scars after using microneedles because of the good elasticity and healing ability of skin.Painless is also one of features of microneedles.In conclusion,the development of insulin microneedles based on silk fibroin has a broad application prospect in this paper.