Phenothiazine–rhodamine‐based colorimetric and fluorogenic ‘turn‐on' sensor for Zn²⁺ and bioimaging studies in live cells

Abstract

A phenothiazine-rhodamine (PTRH) fluorescent dyad was synthesized and its ability to selectively sense Zn 2+ ions in solution and in in vitro cell lines was tested using various techniques. When compared with other competing metal ions, the PTRH probe showed the high selectivity for Zn 2+ ions that was supported by electronic and emission spectral analyses. The emission band at 528 nm for the PTRH probe indicated the ring closed form of PTRH, as for Zn 2+ ion binding to PTRH, the λ em get shift to 608 nm was accompanied by a pale yellow to pink colour (under visible light) and green to pinkish red fluorescence emission (under UV light) due to ring opening of the spirolactam moiety in the PTRH ligand. Spectral overlap of the donor emission band and the absorption band of the ring opened form of the acceptor moiety contributed towards the fluorescence resonance energy transfer ON mechanism for Zn 2+ ion detection. The PTRH sensor had the lowest detection limit for Zn 2+ , found to be 2.89 × 10 −8 M. The sensor also demonstrated good sensing application with minimum toxicity for in vitro analyses using HeLa cells.

Recent advances in the development of phenothiazine and its fluorescent derivatives for optoelectronic applications

“…Karmegam et al reported the phenothiazine–rhodamine based sensor 126 (Chart 5) for Zn 2+ detection. 162 In the presence of Zn 2+ ions, the absorption spectrum of 126 indicated the emergence of a new peak in a higher wavelength region (Fig. 19(a)).…”

Recent Developments in Fluorescent Materials for Heavy Metal Ions Analysis From the Perspective of Forensic Chemistry

“…A new rhodamine B hydrazone derivative was synthesized and showed selective response to Fe 3+ and Cu 2+ ions at 552 and 545 nm, respectively, showing the LOD of 4.63 nM (Fe 3+ ) and 526.4 nM (Cu 2+ ) (Wang et al, 2017 ). A phenothiazine-rhodamine-based fluorogenic sensor was developed for Zn 2+ with a LOD of 289 μM and demonstrated the feasibility of bioimaging use in HeLa cells (Karmegam and Subramanian, 2020 ).…”

Development of a novel Cd(ii) metal complex for solvent-sensitive detection of Zn(ii) and Mg(ii) with the formation of Cd(ii)–Zn(ii)/Cd(ii)–Mg(ii) complexes and their application in effective Schottky devices

“…Many groups of workers have successfully developed organic chemosensors for selective detection of Zn(II) or Mg(II) via turn-on fluorescence. [36][37][38][39] We developed and characterized a mononuclear Schiff base Cd(II) complex, Cd[LH 2 I 2 ] (complex 1). As a chemosensor, this metalloligand can selectively detect Zn(II) and Mg(II) among several competitive cations via turn-on fluorescence.…”

“…Many groups of workers have successfully developed organic chemosensors for selective detection of Zn( ii ) or Mg( ii ) via turn-on fluorescence. 36–39…”