Intelligent Drug Delivery System Based on Silk Fibroin/Wool Keratin

It is critical to develop drug carriers for intelligent drug delivery systems. Normally, the drug carriers of the intelligent drug delivery system are stimulus-responsive polymers. However, as drug carriers, the biocompatibility of the materials should be the primary consideration. In this work, two smart drug systems were prepared using natural protein materials (silk and wool) as drug carriers and poly(N-isopropylacrylamide) (PNIPAM) as a functional additive material. (1) Silk fibroin (SF)/wool keratin (WK) composite films: the differences in drug release efficiency of composite films are based on the different crystallinity of composite films. Analysis of the XRD results showed that the content of the β-crystallite structure in different proportions of the composite films changed from 38.3% to 19.5%. The percentage of drugs released of the mixed films with different proportions ranged from 28% to 58% after eight hours of release, showing a gradient release. (2) SF/WK and PNIPAM composite films: the particle size of the PNIPAM microspheres changed with the temperature. The particles’ size of the prepared PNIPAM microspheres was reduced from 700 nm to 300 nm from 25°C to 35°C. After eight hours of release, the composite films with temperature-sensitive microspheres increased the percentage of drug released by up to 20% compared with the composite films without microspheres when the temperature was ranged from 25°C to 37°C. The result of drug release showed the amount of drug released could be changed with temperature stimulation, which could satisfy people’s controllable requirements for the time, location, and dose of drug release.