Research

Research

Near-infrared light is favorable for imaging in mammalian tissues due to the low absorbance of hemoglobin, melanin, and water. Therefore, fluorescent proteins, biosensors and optogenetic constructs for optimal imaging, optical readout and light manipulation in mammals should have fluorescence and action spectra in the near-infrared spectral region.

Natural bacterial phytochromes (BphPs) utilize the low molecular weight biliverdin, found in most mammalian tissues, as a photoreactive chromophore. Due to their near-infrared absorbance BphPs are preferred templates for designing optical molecular tools for applications in mammals. Moreover, BphPs spectrally complement existing genetically-encoded probes of the GFP, flavoprotein and rhodopsin families.

The chromophore spectrum

 

Based on the analysis of photochemistry and structure of BphPs our laboratory engineers a variety of BphP-based fluorescent proteins, biosensors and optogenetic constructs. Near-infrared proteins and biosensors extend the methods developed for cell microscopy into deep-tissue imaging, including multicolor labeling, FRET, photoactivation and tracking, and detection of enzymatic activities and metabolites. Near-infrared optogenetic tools enable light-manipulations directly through the skin of a living animal. Overall, these optical probes allow noninvasive studies of the chemical and metabolic status, and molecular and cellular interactions in cells, tissues, and whole organisms.