Harvesting red fluorescence through design specific tuning of ICT and ESIPT: an efficient optical detection of cysteine and live cell imaging. Issue 98 (6th October 2016)

• Record Type: Journal Article
• Authors: Diwan, Uzra; Kumar, Virendra; Mishra, Rakesh K.; Rana, Nishant Kumar; Koch, Biplob; Upadhyay, K. K.
• Is Part Of: RSC advances. Volume 6:Issue 98(2016)
• Page Start: 95722
• Page End: 95728
• Publication Date: 2016-10-06
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra18093k
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : In this work, a 2-(2-hydroxyphenyl)benzothiazole (HBT)-based ratiometric fluorescent probe exhibiting coupling between the ICT and ESIPT mechanisms was exploited for the optical sensing of cysteine and successfully utilised in the bio-imaging of cysteine in HeLa cells. Abstract : In this report, we constructed 2-(2-hydroxyphenyl)benzothiazole (HBT) based ratiometric fluorescent probeR1, highly selective for cysteine (Cys) in the red channel with a nanomolar detection limit. The rational combination of benzothiazole and benzothiazolium unit within the same molecular frame work act as "two-heads" that allowed the simultaneous harvesting of intramolecular charge transfer (ICT) as well as excited state intramolecular proton transfer (ESIPT). This coupling of dual mechanism inR1 provides selective colorimetric and ratiometric fluorescence response towards Cys from the mixture of various anions and amino acids including foremost interfering thiols viz. HS −, Hcy and GSH.R1 shows a weak ESIPT at 497 nm (green fluorescence, N*) which undergoes shifting to 625 nm (red channel K*) upon addition of Cys selectively. Henceforth, R1 was also utilized for marking Cys in live cell imaging in HeLa cells. The sensing phenomenon ofR1 for Cys was studied through a number of spectroscopic techniques viz., NMR, IR along with HRMS studies. The density functional theory calculations further strengthened the experimental findings.