Fabrication And Application Of Enhanced Silk Fibroin Microneedles

Microneedles have attracted much attention due to their potential applications in drug delivery,cosmetology,physiological electric signal detection.In recent years,the research of microneedles has gradually shifted from metal microneedles,ceramic microneedles and silicon microneedles to polymer microneedles.Because some polymer microneedles have good biocompatibility,simple preparation method,good plasticity and it can greatly increase drug loading.Polyvinyl pyrrolidone(PVP),poly(lactic-co-glycolic acid)(PLGA)and chitosan microneedles are the main polymer microneedles.Polymer microneedles also have some limitations,such as their mechanical strength is generally lower than that of metal and silicon microneedles.Silk fibroin(SF)is a kind of natural protein with good biocompatibility,biodegradability and easy processing.The most important characteristic of SF is that its mechanical properties can be enhanced by adjusting the secondary structure of SF.By fabricating silk microneedles and improving their mechanical properties,the drug controlled and sustained release system of silk microneedles and microneedle electrodes were constructed,which is expected to be applied in medical life.The main work of this article contains two parts as follow:1.Transdermal drug delivery has always been the focus of research.Microneedles as the carrier of new drug delivery,of which the greatest advantage is minimally invasive painless drug delivery.In this paper,we use micro template method,using 200 micron height silicon microneedle as template,using polydimethylsilane(PDMS)transfer template,and then adding glutaraldehyde crosslinking agent to the fibroin solution to prepare microneedle,finally forming the glutaraldehyde crosslinked silk microneedle.The high strength silk microneedles were prepared by water vapor treatment of the prepared silk microneedles.After that,the high-strength silk needle was characterized by Fourier transform infrared spectrum and X-ray diffractometer.The results show that the silk microneedles treated with glutaraldehyde and water vapor have higher mechanical strength,which is more conducive to piercing the skin and reduce the loss of materials and drugs.On the basis of preparing high-strength silk microneedle,a double layer silk microneedle was constructed by dip-coating,and the drug was released slowly.By characterizing the release of the loaded model drug horseradish peroxidase(HRP),it was observed that the microneedles can carry macromolecular drugs and maintain their activity;Using fluorescence spectrophotometer to determine the release of the model drug r hodamine B,it was found that the microneedles can carry small molecular drugs and release drug.This research provides theoretical guidance for the enhancement of the mechanical strength of silk materials and establishes a new microneedles for drug delivery.2.In this paper,the silver nanowires are synthesized by the polyol method,and then the PDMS is poured on the silicon microneedle template to prepare the negative template,and then the silver nanowires are dispersed on the negative template,and the fibroin solution is poured into the negative template after the water vaper post-treatment.Silk microneedle electrode was prepared.It is a relatively new material with a lower cost than a market-oriented physiological electrical test electrode.The microneedle electrode can penetrate the dense stratum corneum with high impedance,and it is simple to use and basically painless.The microneedles attached to silver nanowires are prepared,which have water insolubility and skin piercing ability.This research will provide new ideas for the development of microneedle electrode materials.