Highly fluorescent quinone-capped silver hydrosol for environmental remediation and sensing applications.

A metal-enhanced fluorescence was achieved from in situ-generated Ag nanoparticles in the proximity of 2-hydroxy benzaldehyde (2HB). Such nanoparticles eliminated methyl blue (MB) dye from water exclusively in the presence of Zn and were proven to be an efficient adsorbent for environmental remediation (maximum uptake capacity 1065 mg·g). Ag was zero valent in the absorbent, while Zn was in Zn(OH) form. Fe brought back MB in the aqueous medium due to the strong interaction of MB with Fe and the regeneration of blue color helped to design a selective and sensitive Fe sensing platform colorimetrically (linear detection range 10-10 M; linear detection limit 10 M). The silver nanoparticle-induced metal-enhanced fluorescence was quenched efficiently with MB. Pb restored the quenched fluorescence by removing MB from the proximity of the metalized surface of silver, and Pb sensing was performed fluorometrically (linear detection range; 10-5 × 10 M limit of detection 5 × 10 M). Iron and lead were also estimated in a variety of natural water sources, including rainfall, drinking water from taps, and water from the Ganga River via spiking method.