the invention provides a method for the controlled assembly of layered silk fibroin coatings using aqueous silk fibroin material . the methods described herein can be used to coat substrates of any material , shape , or size . importantly , the described methods enable control of the biomaterial surface chemistry , thickness , morphology and structure using layered thin film coatings , or bulk coatings . furthermore , the methods can be performed in all water and do not require intensive chemical processing enabling controlled entrapment of labile molecules such as , drugs , cytokines , and even cells or viruses to generate functional coatings that can be used in a variety of applications .