Formation of platinum-coated templates of insulin nanowires used in reducing 4-nitrophenol.

Modern technology demands ever smaller and more efficient nanoparticles, wires and networks. The natural tendency for amyloid proteins to form fibrillar structures is leveraged in creating high aspect ratio, nano-sized protein fibers as scaffolds for metallized nanowires. The morphology of fibrils is influenced by induced strain during denaturing and early aggregation and subsequent fibril deposition with platinum leads to controlled catalyst surfaces based on the initial protein precipitate. Here we have created insulin fibrils with varying morphologies produced in the presence of heat and strain and investigated their metallization with platinum by TEM. The catalytic activity of the metal-coated protein fibrils was resolved by tracking the reaction kinetics of the conversion of 4-nitrophenol to 4-aminophenol in the presence of the produced nanowires using UV-Vis spectroscopy. The effects of fibril morphology and temperature on the pseudo-first-order kinetics of conversion are investigated. Conversion to 4-aminophenol occurs on the order of minutes and is independent of temperature in the range tested (7 to 20°C). Two regimes of conversion are identified, an early higher rate, followed by a slower later rate.