Preparation Of HMS-based Chemosensor For Detection Of Mercury Ion In Aqueous Media

Mercury is regarded as one of the most toxic and dangerous heavy metal elements. So much attention has been focused on developing new methods to detect Hg2+in biological and environmental samples. Fluorescent probe is one of the analytical applications that has excellent selectivity, sensitivity and real-time detection ability. Although these offer considerable advantages over other methods, there is still a growing demand to solve one of the major technological challenges in fluorescence-based probes:the reversibility and regeneration of the materials. In order to enhance the detection ability of the fluorescent probe, several novel HMS-based optical sensors have been prepared.RhB-APTES-HMS that used3-aminopropyl-triethoxysilane (APTES) as the connector was prepared by forward and inverse method. The result showed that APTES destroyed the inner channel structure of HMS and RhB-APTES-HMS did not possess the worm-like structure. RhB-APTES-HMS that was prepared by forward method had better detection ability than that by inverse method, and owned highly selective and competitive detection of Hg2+in aqueous media. RhB-APTES-HMS could be regenerated by treatment with tetrapropylammonium hydroxide solution.RhB-Tri-HMS that used3-(triethoxysilyl)propylisocyanate (Tri) as the connector was also prepared by forward and inverse method. The result showed that Tri did not destroy the inner channel structure of HMS, but the outer morphology of HMS was destroyed. RhB-Tri-HMS prepared by inverse method had better detection ability than that by forward method, and owned highly selective and competitive detection of Hg2+in aqueous media. At the same time, RhB-Tri-HMS had high sensitivity for Hg2+detection with a detection limit of0.1ppb. The association constants between RhB-Probe or RhB-Tri-HMS and Hg2+were3.22×103M-1,1.71×104M-1, respectively, which suggested that the complex of RhB-Tri-HMS-Hg2+was more stable than that of RhB-Probe-Hg2+. RhB-Tri-HMS could also be regenerated by treatment with tetrapropylammonium hydroxide solution. Au-HMS-Probe was prepared by using gold nanoparticles as connectors. The result showed that gold nanoparticles had no effect on the structure of HMS. Au-HMS-Probe had tunable wormlike pore structures and smooth outer surface. Compared with the previous chemosensors which were used silane agents as the connectors, Au-HMS-Probe had excellent detection ability and owned highly selective and competitive detection of Hg2+in aqueous media. RhB-Tri-HMS had high sensitivity for Hg2+detection with a detection limit of7×10-8M. The linear fitting of the titration curve confirmed a1:1stoichiometry between Au-HMS-Probe and Hg2+with the association constants of3.7×105M-1Tetrapropylammonium hydroxide solution could achieve Au-HMS-Probe regeneration. Au-HMS-Probe which was used gold nanoparticles instead of silane agents as connectors showed better detection ability. The simple immobilization method of Au-HMS-Probe was beneficial to preserve the worm like structure. At the same time, Au-HMS-Probe had stronger detection ability than the previous chemosensors.