In vitro characterization of selected NIR FPs

Absorbance, steady-state fluorescence spectra and two-photon cross-section spectra of the selected NIR FPs measured by Mikhail Drobizhev. Recent progress in fluorescent protein development has generated a large diversity of near-infrared fluorescent proteins, which are rapidly becoming popular probes for a variety of imaging applications. To assist end-users with a selection of the right near-infrared fluorescent protein for a given application, we conducted a quantitative assessment of intracellular brightness, photostability, oligomeric state, and cytotoxicity of 22 near-infrared fluorescent proteins in cultured HEK cells and primary mouse neurons. The top-performing proteins were further validated for in vivo imaging of neurons in C. elegans, zebrafish, and mice as well as in liver of mice. We also assessed the applicability of the selected NIR FPs for multi-color imaging of fusions, expansion microscopy, and two-photon imaging.