Simple Colorimetric and Fluorescence Chemosensing Probe for Selective Detection of Sn2+ Ions in an Aqueous Solution: Evaluation of the Novel Sensing Mechanism and Its Bioimaging Applications

An easily accessible colorimetric and fluorescence probe 4((3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)amino)-benzenesulfonamide (4CBS) was successfully developed for the selective and sensitive detection of Sn2+ in an aqueous solution. The sensing mechanism involves reduction of -C=O into -C-OH groups in 4CBS upon the addition of Sn2+, which initiates the fluorescence turn-on mode. A better linear relationship was achieved between fluorescence intensity and Sn2+ concentration in the range of 0-62.5 mu M, with a detection limit (LOD) of 0.115 mu M. The binding mechanism of 4CBS for Sn2+ was confirmed by Fourier transform infrared analysis, NMR titrations, and mass (electrospray ionization) spectral analysis. Likewise, the proposed sensing mechanism was supported by quantum chemical calculations. Moreover, bioimaging studies demonstrated that the chemosensing probe 4CBS is an effective fluorescent marker for the detection of Sn2+ in living cells and zebrafish. Significantly, 4CBS was able to discriminate between Sn2+ in human cancer cells and Sn2+ in normal live cells.

Automated summary

4CBS is an easily accessible colorimetric and fluorescence probe for the selective and sensitive detection of Sn2+ in aqueous solutions. It shows a good linear relationship and low detection limit, with the binding mechanism to Sn2+ confirmed by FT-IR, NMR, and mass spectral analysis, and the proposed sensing mechanism supported by quantum chemical calculations. Additionally, 4CBS is effective for bioimaging studies and can discriminate between Sn2+ in human cancer cells and Sn2+ in normal live cells.