Noncontact mode atomic force microscopy was used to investigate native silk proteins
prepared in different ways. Low protein concentrations revealed that single protein
molecules exhibit a simple, round shape with apparent diameters of 20–25 nm. Shearing the
native protein solutions after extraction from the gland and prior to drying led to a beads-on-
a-string assembly at the nanometer scale. Protein concentration had a significant effect on
the morphology of the protein assemblies. At higher protein concentrations, shear-induced …