Long Distance Electron Transfer Across >100 nm Thick Au Nanoparticle/Polyion Films to a Surface Redox Protein

Glutathione-decorated 5 nm gold nanoparticles (AuNPs) and oppositely charged poly(allylamine hydrochloride) (PAH) were assembled into {PAH/AuNP} films fabricated layer-by-layer (LbL) on pyrolytic graphite (PG) electrodes. These AuNP/polyion films utilized the AuNPs as electron hopping relays to achieve direct electron transfer between underlying electrodes and redox proteins on the outer film surface across unprecedented distances >100 nm for the first time. As film thickness increased, voltammetric peak currents for surface myoglobin (Mb) on these films decreased but the electron transfer rate was relatively constant, consistent with a AuNP-mediated electron hopping mechanism.