Protein crystallization induced by strong photons–molecules coupling fields photochemical reaction

Photochemically induced protein crystallization byproteinʹs multiphoton excitation based on enhanced field of localized surface plasmon resonance (LSPR) of gold nanostructures was investigated. As strong photons–molecules coupling fields, gold nanostructures composed of nanoblocks and gold nanocolloid were used. With gold nanostructures, we could observe enzyme activity decrease by light irradiation that protein does not absorb. Surface observation of gold nanostructure by DFM (non-contact dynamic force microscope) shows that proteins were aggregated at around the nanoblock due to photochemical reaction by enhanced field. Crystallization probability depends on the excitation photon fluence, which indicates 3 photons absorption process occurred.