Electronic system for FRET based in vitro sensing of cytosolic Ca2+ in INS-1E pancreatic β-cells

This work reports the development of a compact bioelectronics system to measure cytosolic [Ca2+] in-vitro in living INS-1E pancreatic β cells using a 430 nm excitation light. By expressing a genetically encoded FRET based Ca2+ sensor, the cells emit light. The system has a linear response and has been characterized for fluorescence for various intensities of light. The system is sensitive for 2D cell cultures on normal petri dishes. Forming cell aggregates using 3D cell culturing techniques increases the number of cells and thus enhances the signal quality 35x and 21x for green and blue lights, respectively. The system has been able to continuously monitor the fluorescence of a clone of INS-1E β-cells upon glucose stimulation, diazoxide injection and KCl injection, thus revealing insights in the cell response mechanisms.