Design of a novel naked-eye and turn-on fluorescence sensor based on the 5,10,15,20-(4-sulphonatophenyl) porphyrin (TPPS4)-Hg2+ system: Monitoring of glutathione (GSH) in real samples and DFT calculation

•An excellent water-solubility 5,10,15,20-(4-sulphonatophenyl)porphyrin (TPPS4) is the first time to be used to sensitive investigate GSH in real samples.•The fluorescence intensity of TPPS4 was quenched by Hg2+ with the change of the solution color after Hg2+ capture.•In the presence of GSH, the fluorescence sensor was switched to the “ON” state, and the solution color changed after the coordination between GSH and Hg2+.•Under the optimal conditions, the naked-eye detection limit was 0.43 nM and the limit of detection (LOD) was 16 fM for GSH.•TPPS4-Hg2+ fluorescence probe has excellent selectivity, high sensitivity and quick fluorescence response for GSH.

In the present work, we proposed a novel naked-eye and turn-on fluorescence sensor based on the 5,10,15,20-(4-sulphonatophenyl) porphyrin (TPPS4)-Hg2+ system with short assay time and high sensitivity to detect glutathione (GSH) in real samples. The TPPS4 was the first time to detect GSH because of its high fluorescence quantum yield. The initial fluorescence from TPPS4 was quenched by Hg2+ with an electron transfer process. However, when put a certain concentration of GSH into this system, the fluorescence sensor was turned to the “on” state, which was related to a competitive affinity of Hg2+ to GSH and the N atoms of porphyrin ring. Under the optimal conditions, the naked-eye detection limit was 0.43 nM and the limit of detection (LOD) was arrived to 16 fM (S/N = 3) for GSH. The linear regions are obtained by two ranges varying from 0 to 28.5 μM and from 38.15 to 61.87 μM. Furthermore, it was confirmed that the TPPS4-Hg2+ fluorescence probe has excellent selectivity, high sensitivity and quick fluorescence response for GSH.

Graphical abstractDownload high-res image (134KB)Download full-size imageA novel naked-eye and turn-on fluorescence sensor based on the TPPS4-Hg2+ fluorescence probe was proposed to detect GSH in real samples with high sensitivity and selectivity for the first time. Based on the electrons transfer (ET) from TPPS4 to Hg2+ and the coordination between Hg2+ and GSH, we designed a colorimetric and fluorescence sensor for GSH. The sensor displayed several appealing properties, including low cost, simple and convenient, high sensitivity, excellent selectivity, and quick fluorescence response.