Biocompatible,small-sized but well-dispersed gold nanoparticles (Au NPs) remain a major challenge for their synthesis.Here a convenient solution impregnation technique is developed to prepare such Au NPs under the regulation of degummed silk fibroin fibers (SFFs) extracted from Bombyx mori cocoons.SFFs play multiple roles in the formation ofAu NPs such as reactive substrate to capture AuCl4-ions by the chelation of-C =O,reducing agent for Au(0) by the reduction of-OH,and modifiers to render biocompatible Au NPs by some functional groups and biomolecules.The as-prepared Au NPs with a size of 7-10 nm are embedded in the solid SFF substrate,and can disperse well in the liquid system by the disintegration of SFFs into silk fibroin (SF) in a certain CaCl2 solution.The biocompatible Au NPs exhibit uniform small size and distribute stably in both solid and solution states,which have distinctive properties and functional advantages,and bring great convenience to their storage and transportation.