Facile preparation of fluorescent Au nanoclusters-based test papers for recyclable detection of Hg2+ and Pb2+

A simple, portable and recyclable method has been developed for on-site and real-time detection of Hg2+ and Pb2+ by naked eyes by using Au nanoclusters-based test paper as the fluorescent sensor. The high specificity of Hg2+ and Pb2+ to Au nanoclusters provided excellent selectivity over 15 kinds of other ions. Interestingly, an apparent fluorescent quenching of the test paper was shown when exposed to Hg2+, while a significant fluorescent enhancement was observed in the presence of Pb2+, which could be attributed to aggregation-induced fluorescence quenching and enhancement. The limit of detection for Hg2+ and Pb2+ by naked eyes was 5 μM and 50 μM, respectively. More importantly, the cyclic utilization of the test paper was achieved by immersing the test papers into ethylenediamine tetraacetic acid to recover the fluorescence of the test paper, which contributed to reducing resource consumption. Otherwise, the GSH-AuNCs test paper was competent for a practical application in environmental water samples with strong anti-interference ability.