Why Image with Near-infrared Wavelengths?

The sensitivity of fluorescence microscopy measurements, especially in living tissues, is often limited by autofluorescence - the natural emission of light by certain biological molecules. Autofluorescence interferes with and obscures the detection of extrinsic fluorescent contrast agents, causing structures other than those of interest to become visible and manifest as a high background signal in an image that reduces contrast and clarity. Autofluorescence spectra are generally broad and encompass most of the visible spectral range, overlapping with the emission wavelengths of green fluorescent protein (GFP) and other common visible wavelength fluorescent probes. This application note explains how near-infrared (NIR) imaging eliminates tissue autofluorescence, solving this problem.