Real-time hyperspectral fluorescence imaging of pancreatic β-cell dynamics with the image mapping spectrometer

The development of multi-colored fluorescent proteins, nanocrystals and organic fluorophores, along with the resulting engineered biosensors, has revolutionized the study of protein localization and dynamics in living cells. Hyperspectral imaging has proven to be a useful approach for such studies, but this technique is often limited by low signal and insufficient temporal resolution. Here, we present an implementation of a snapshot hyperspectral imaging device, the image mapping spectrometer (IMS), which acquires full spectral information simultaneously from each pixel in the field without scanning. The IMS is capable of real-time signal capture from multiple fluorophores with high collection efficiency (~65%) and image acquisition rate (up to 7.2 fps). To demonstrate the capabilities of the IMS in cellular applications, we have combined fluorescent protein (FP)-FRET and [Ca²⁺]i biosensors to measure simultaneously intracellular cAMP and [Ca²⁺]i signaling in pancreatic b-cells. Additionally, we have compared quantitatively the IMS detection efficiency with a laser-scanning confocal microscope.