A new method for determination of polysaccharides in adsorption of Hg2+

Bacterial extracellular polysaccharides (EPS) has a good heavy metal ion adsorption function and can be used in sewage treatment of heavy metal pollution. In this work, we develop a new, label-free, turn-on fluorescent sensor for detecting EPS adsorbed Hg2+. This approach is based on the conformational switch from G-quadruplex complex induced by fluorogenic dye Thioflavin T (ThT) to Hg(2+)mediated T-Hg-T double-stranded DNA formation. By this method, Hg2+ in aqueous solution can be detected by fluorescence spectroscopy in the range of 5-1200 nM. The entire reaction and analysis of Hg2+ was performed in 10 min under optimal experimental conditions (1.4 mu M ThT, 0.35 mu M TBA, 1.2 mu M Hg2+ and 10 min incubation time at 25 degrees C, pH7.5). Then, we have utilized this facile approach to detect the adsorption properties of different EPS on Hg2+ with fluorescence spectrometry. These EPS were produced by the fermentation of Pseudoalteromonas sp. BAY, Bacillus sp. RS1, Mesonia sp. Hua40 and Bacillus sp3. SL7 respectively. The Hg(2+ )adsorption capacity of EPS is between 80.1 mg/g to 169.6 mg/g. Among them, the extracellular polysaccharides of Mesonia sp. Hua40 have the strongest Hg(2+ )adsorption capacity, about 169.6 mg/g. This method provides an effective detection technique to analyze Hg2+ adsorption capacity of EPS.

Automated summary

A new label-free fluorescent sensor has been developed for detecting Hg2+ adsorbed by EPS. This sensor allows for the detection of Hg2+ in aqueous solution using fluorescence spectroscopy, and has been used to successfully analyze the adsorption properties of different EPS on Hg2+. It provides an effective detection technique for heavy metal pollution treatment using EPS.