Oligonucleotide-templated rapid formation of fluorescent gold nanoclusters and its application for Hg²⁺ ions sensing

In this work, we developed a simple, rapid and mild strategy for synthesis of DNA-templated fluorescent gold nanoclusters (AuNCs) through association of gold ions to DNA templates and reduction with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES). After systematical investigation on the formation of fluorescent AuNCs by using different DNA templates, C5 DNA was found as the best template for the formation of fluorescent AuNCs in this system. This process could be completed within 5min after the reaction beginning under ambient conditions. The prepared C5-AuNCs displayed good blue emission and photostability. Furthermore, this C5-AuNCs could be applied to detecting Hg²⁺ ions specifically based on the specific and strong interaction between Hg²⁺ and Au⁺. The C5-AuNCs provided excellent selectivity for Hg²⁺ ions over other metal ions, and also high sensitivity, with a detection limit of 50nM. As biocompatible, environmentally-friendly, and synthesis-rapid, this C5-AuNCs probe appears to be promising candidate for biochemical sensing via simple modification of template DNA.