A versatile click-grafting approach to surface modification of silk fibroin films

Silk fibroin is a biocompatible, mechanically robust protein polymer that can be made optically transparent, and is widely used and studied as biomaterial for different applications. Its chemical modification is a fascinating way for tuning the properties and widening its application field. Herein, PEG grafting on the surface of regenerated silk fibroin films is obtained by direct linking based on a click reaction between the azido activated silk surface and an alkyne terminated PEG. The so obtained PEGylated films exhibit modified surface properties in comparison with the unmodified films. Through the same click approach, we also show that arrays of ordered fluorescent spots are steadily printed onto the film surface. This expands the versatility of our silk modification to different molecules and polymers, hence allowing for the realization of new functional hybrid materials.