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G-protein coupled receptor (GPCRs) drug discovery is a thriving strategy in the pharmaceutical industry. The standard approach uses living cells to test millions of compounds in a high-throughput format. Typically, changes in the intracellular levels of key elements in the signaling cascade are monitored using fluorescence or luminescence read-out systems, which require external equipment for signal acquisition. In this work, thin-film amorphous silicon photodiodes with an integrated fluorescence filter were developed to capture the intracellular calcium dynamics in response to the activation of the endogenous muscarinic M1 GPCR of HEK 293T cells. Using the new device it was possible to characterize the potency of carbachol (EC50=10.5 µM) and pirenzepine (IC50=4.2 μM), with the same accuracy as standard microscopy optical systems. The smaller foot-print provided by the detection system makes it an ideal candidate for the future integration in microfluidic devices for drug discovery., (© 2013 Elsevier B.V. All rights reserved.)

Abstract: Microfabricated amorphous silicon photodiodes have been used to monitor the increase of fluorescence in living cells following calcium release into the cytosol in response to G-protein coupled receptors (GPCR) activation. A signal acquisition system was developed, enabling real-time monitoring of the calcium fluxes by fluorescence. Calibration of the emission light versus calcium concentration demonstrates the possibility of single cell monitoring with this setup. The developed system enabled the detection of 0.5mM agonist-induced calcium fluxes with accuracy comparable to traditional optical systems. [Copyright &y& Elsevier]