Synthesis and Properties of Gold Nanoparticle Arrays Self-Organized on Surface-Deposited Lysozyme Amyloid Scaffolds

In this study, amyloid fibers prepared from hen egg white lysozyme (HEWL) are specifically mediating the assembly of citrate-capped gold nanoparticles, on glass and silicon substrates. The organization of nanoparticles is investigated for nanoparticle diameters of 5, 15, and 25 nm, using variable deposition times, and under a range of pH, salt, citric acid and nanoparticle concentrations. The observed periodic self-organization of nanoparticles is mainly influenced by the interparticle interactions rather than by the spacing of binding groups at the surface of the amyloid fiber template. For a fixed ionic strength of 2.3 mM and particle concentration, the interparticle distance increases with the nanoparticle diameter in agreement with the values predicted by the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory. UV–visible spectroscopy measurements show a red shift of the 520 nm plasmon absorption peak associated with spherical gold nanoparticles up to 650 nm upon aggregation or decrease in the interparticle distance. Such protein templates deposited on technologically relevant surfaces allow the self-assembly of inorganic nanoparticle arrays with functional optoelectronic properties.