Disclosed herein is a method of controlling the stability of multilayer
polypeptide films. A method of controlling the stability of a film,
comprises exposing the film to an oxidizing agent or a reducing agent,
wherein the film comprises a plurality of layers, the layers comprising
alternating oppositely charged polypeptides, wherein a first layer
comprises a first layer polypeptide and a second layer comprises a second
layer polypeptide, and the first layer polypeptide comprises a
sulfhydryl-containing amino acid.