In a study published online on December 1 in Nature Methods, Vladislav Verkhusha, Ph.D., and colleagues described a unique small cyanobacteriochrome-based near-infrared (NIR) fluorescent protein (FP) they have engineered, called miRFP718nano. This new FP allows cells and tissues deep inside living animals to be visualized in the second NIR tissue transparency window, also known as the short-wavelength infrared (SWIR) window. To develop miRFP718nano, the researchers applied a structure-based rational design to a previously developed protein, followed by directed molecular evolution. miRFP718nano-enabled SWIR imaging has superiority over imaging in the first NIR transparency window in many applications, including but not limited to: microbes in the mouse digestive tract, cancer cells in the mouse mammary gland, and NF-κB activity in a mouse model of liver inflammation. The new genetically encoded FP does not require complex delivery from outside the organism, which is necessary when using synthetic NIR organic dyes.

Dr. Verkhusha is professor of genetics, director of the Fluorescent Protein Resource Center and co-director of the Gruss Lipper Biophotonics Center at Einstein. Albert Einstein College of Medicine has filed a patent application related to this research and is interested in partnering to further develop and commercialize this technology.