High-Sensitive and Rapid Fluorescencet Detection of Hg2+ Based on Poly (adenine)-Templated Gold Nanoclusters

Poly adenine (Poly A)-templated gold nanoclusters (Poly A-AuNCs) have many advantages, such as facile and fastly synthesis, excellent fluorescence intensity and good photostability. Based on Poly A-AuNCs, a sensitive, simple, rapid and novel fluorescent strategy was developed for the detection of Hg2+. AuNCs were prepared by heating-assisted methods with sodium citrate as a reductant. The AuNCs have been revealed by fluorescence spectra and transmission electron microscopy (TEM). TEM showed that the AuNCs were spherical in shape and well dispersed. The average size of AuNCs is approximately 7 nm. The fluorescence spectra showed that AuNCs emitted strong blue fluorescence with maxima fluorescence emission wavelengths at 471 nm upon excitation at 280 nm. Additionally, the AuNCs were highly stable and little fluorescence change was observed after storing at 4 V for 1 month. In the presence of Hg2+, the fluorescence of AuNCs was quenched effectively due to the high affinity between Hg2+ and gold. The pH and reaction time was investigated. The fluorescence of AuNCs were insensitive to pH. The quenching reaction between Hg2+ and AuNCs was very fast and was completed within the first 1 min. Thus, the fluorescence was recorded after the simple mixture of Hg2+ and AuNCs. Under optimum conditions, a series concentration of Hg2+ was detected. The linear equation is y= - 335. 57x+541. 35. The relative fluorescence intensity displayed a good linear relationship with Hg2+ concentration in the range from 0. 01 to 1 mu mol . L-1 with the detection limit of 3 mu mol . L-1. Nine metal ions were added in the system to assess the sensing selectivity. Furthermore, the assay was successfully applied for the detection of Hg2+ in environmental water samples with good recoveries from 95. 33%-103. 8%, and the relative standard deviation was lower than 4%. Thus, this novel strategy was rapid, simple and have high sensitivity and good selectivity for Hg2+.