Heng, S.Mak, A.Kostecki, R.Zhang, X.Pei, J.Stubing, D.Ebendorff-Heidepriem, H.Abell, A.2018-03-192018-03-192017Sensors and Actuators B: Chemical: international journal devoted to research and development of physical and chemical transducers, 2017; 252:965-9720925-40050925-4005http://hdl.handle.net/2440/111112Calcium is a ubiquitous intracellular signaling ion that plays a critical role in the modulation of fundamental cellular processes. A detailed study of these processes requires selective and reversible sensing of Ca2+ and an ability to quantify and monitor concentration changes in a biological setting. Three new, rationally designed, synthesized and photoswitchable spiropyran-based reversible sensors for Ca2+ are reported. Sensor 1a is highly selective for Ca2+ with an improved profile relative to the other two analogues, 1b and 1c. Formation of the merocyanine–Ca2+ complex is proportional to an increase in Ca2+ released from HEK293 cells on stimulation with ionomycin. The photophysical processes surrounding the binding of Ca2+ to compound 1a were further explored using computational methods based on density functional theory (DFT). The ability of sensor 1a to bind Ca2+ and photoswitch reversibly was also characterized using silica suspended-core microstructured optical fiber (SCF). These SCF experiments (with 100 nM Ca2+) represent a first step toward developing photoswitchable, minimally invasive and highly sensitive Ca2+ sensing platforms for use in a biological setting.en© 2017 Elsevier B.V. All rights reserved.Spiropyran; calcium sensing; density functional theory; suspended-core microstructured optical fiberJournal article003007204910.1016/j.snb.2017.06.0510004082775001152-s2.0-85021121866358557Kostecki, R. [0000-0001-5822-8401]Pei, J. [0000-0003-2453-929X]Ebendorff-Heidepriem, H. [0000-0002-4877-7770]Abell, A. [0000-0002-0604-2629]