Visible Light-Activated Photosensitization of Hybridization of Far-red Fluorescent Protein and Silk

Fluorescent proteins often result in phototoxicity and cytotoxicity, in particular because some red fluorescent proteins (RFP) produce and release reactive oxygen species (ROS). The photogeneration of ROS is considered as a detrimental side effect in cellular imaging or is proactively utilized for ablating cancerous tissue. As ancient textiles or biomaterials, silk produced by silkworms can directly be used as fabrics or be processed into materials and structures to host other functional nanomaterials. We report that transgenic fusion of far-red fluorescent protein (mKate2) with silk provides a photosensitizer hybridization platform for photoinducible control of ROS. Taking advantage of green (visible) light activation, native and regenerated mKate2 silk can produce and release superoxide and singlet oxygen, in a comparable manner of visible light-driven plasmonic photocatalysis. Thus, the genetic expression of mKate2 in silk offers immediately exploitable and scalable photocatalyst-like biomaterials. We further envision that mKate2 silk could potentially rule out hazardous concerns associated with foreign semiconductor photocatalytic nanomaterials.