Dihydroquinazolinone based nanosensor for fluorimetric detection of Hg2+ ions: Application to environmental analysis

Abstract

We describe a simple, selective, and sensitive method to detect Hg2+ ions using fluorescent 2-(thiophen-2-yl)-2,3-dihydroquinazolin-4(1H)-one (TDHQ) derivative based organic nanoparticles TDHQNPs. TDHQNPs thus prepared were first characterized by zeta particle sizing and scanning electron microscopy to investigate the formation of the desired nanoparticle TDHQNPs along with their aqueous stability, surface charge, particle size, and morphological features, while the comparative optical properties between the parent molecule TDHQ and TDHQNPs have been studied by UV–Vis and fluorescence measurements. Under the optimized conditions, the fluorescence study revealed a selective and sensitive interaction with only Hg2+ in the set of coexisting species examined, which was further revealed by fluorescence titration studies. The interaction between TDHQNPs and Hg2+ leads to fluorescence quenching of TDHQNPs due to electrostatic metal-ligand interaction. In addition, the quenching mechanism was investigated by lifetime and zeta particle size measurements, which revealed a static nature upon increasing the Hg2+ ion concentration. The detection limit calculated with the present method was 0.00329 μg.mL−1 in the concentration range from 0 to 100 μg.mL−1. In addition, the fluorescence quenching results were used to further develop an analytical method to estimate Hg2+ from real samples.