Enzyme-Mediated In Situ Synthesis and Deposition of Nonaggregated Melanin Protoparticles

The previously introduced process for enzyme-mediated in situ synthesis and deposition of eumelanin is investigated with covalent immobilization of the tyrosinase. It results in a monolayer structure of non-coalesced melanin particles, with a film thickness of 5-8 nm. The reaction is self-terminating due to overlay of the enzymes with particles. The melanin particles are rodlike with lengths down to 6 nm. Isolated melanin structures of such small size have not been observed before and might be a kind of protoparticle in the supramolecular buildup of melanin oligomers. Utilization of melanin particles with such small size can enable nanotechnological applications in the areas of bioelectronics and biosensors.