Engineering excitation-independent turn-on fluorescent probe for mercury: Functionalized dendritic silica doped with red-emissive carbon dots towards simultaneous detection and remediation with biosensing application

Abstract

The simultaneous detection and remediation of highly toxic mercury-ion are urgently needed for environmental benefits. However, most of the fluorescence probes for mercury-ion exhibit blue luminescence with fluorescence quenching, and the simultaneous functions are scarce. Therefore, a new strategy is adopted to observe turn-on fluorescence with mercury-ion using red-emissive carbon dots (CDs) as a fluorescence tag and alkyl thiol functionalized dendritic fibrous nano-silica (DFNS@SH) as a substrate for specificity. The newly constructed composite material (CD@DFNS@SH) shows excitation-independent selective turn-on red luminescence in the presence of mercury-ion with a LOD (limit of detection) value of 5 nM, which is well below the threshold limit prescribed by the World Health Organization (WHO) in drinking water. In addition, this material also shows a high adsorption capacity toward mercury remediation (695 mg g−1) from the aqueous system. The adsorption parameters are best fitted with the Langmuir model with a pseudo-second-order interaction mechanism. Furthermore, fluorescence imaging used the composite material for biosensing of mercury-ion in living organisms, Artemia Salina (brine shrimp). The material's real sample quantification of mercury-ion and recyclability are other advantages offered by this material.