2, Rural Development Administration, Wanju, , Korea (the Republic of)
3, Purdue University, West Lafayette, Indiana, United States
Photocatalysis has received consideration attention for a variety of energy, environmental, and biomedical applications, such as hydrogen generation, and water/air purification, carbon dioxide reduction, desalination, and disinfection. Recently, visible light-driven plasmonic photocatalysis consisting of noble metal (e.g. Au and Ag) and semiconductor nanoparticles have been widely studied. To overcome the drawback of photoabsorption only in the ultraviolet region (< 420 nm) for typical semiconductor photocatalysts (e.g. TiO2 and ZnO) with wide bandgap energy (> 3.0 eV). However, such approaches are often intrinsically limited for large-scale and eco-friendly production. In addition, potentially hazardous effects associated with semiconductor nanoparticles have limited the widespread utilization for environmental remediation. In this respect, our study is focused on identifying and characterizing plasmonic photocatalyst-like materials that exist in nature. We report that transgenic hybridization of far-red fluorescent protein (mKate2) and silk serves a new class of genetically encoded photosensitization activated by green (visible) light, generating selective reactive active species (ROS) of superoxide anion (O2-) and singlet oxygen (1O2) in a similar manner of plasmonic photocatalysis. The ROS of O2- and 1O2 generated from mKate2 silk are detected using fluorescent sensing probes. Its photocatalytic effects are demonstrated on organic dye removal and bacteria inactivation. Even more, mKate2 silk can be mass-produced by scalable and continuous manufacturing using the currently available textile infrastructure. Using the polymeric nature of silk, mKate2 silk can also be processed into nanomaterials and nanostructures in a variety of forms. mKate2 silk can overcome the limitation of potential adverse effects associated with foreign nanoparticles. Thus, we envision that this bioreactor could potentially open an alternative green manufacturing strategy for the next-generation of visible light-driven photocatalysts.