Photochemically Induced Crystallization of Proteins Accelerated on Two-Dimensional Gold Gratings

Abstract

The photochemically induced crystallization of lysozyme was studied on a two-dimensional surface relief grating coated with a thin gold film (2D-plasmonic chip), a flat thin gold film, and a flat UV-curable resin. The lysozyme solution prepared in a metastable compositional region was dropped on each surface. After an exposure to visible light from a filtered Hg lamp (500 and 800 nm in wavelength, 1.5 W/cm2) for 30 min followed by 18 h keeping in the dark, the crystal particles were observed in the droplets. Under a microscope, the numbers of crystalline particles were counted to be 1280, 258, and 180 on the 2D-plasmonic chip, the flat gold film, and the flat UV-curable resin, respectively. It was suggested that the crystallization tendency of lysozyme was effectively accelerated by the enhanced electric field caused by the coupling of incident light with surface plasmon polaritons on the 2D-plasmonic chip.