Silver nanoclusters as fluorescent nanosensors for selective and sensitive nitrite detection

As a highly carcinogenic pollutant but also an important food preservative, nitrite has attracted growing attention in the past few years. In this work, a hyperbranched polyethyleneimine protected silver nanocluster (hPEI-Ag NC) based nanosensor is proposed for the detection of nitrite. The sensing principle consists of two steps: nitrite reacts with hydrogen peroxide (H₂O₂) to generate peroxynitrous acid under acidic conditions, and the as-formed peroxynitrous acid then induces the aggregation and fluorescence quenching of hPEI-Ag NCs. Due to the specific nitrite-H₂O₂ chemistry, the hPEI-Ag NC based nanosensor shows high selectivity toward nitrite over other anions with a limit of detection of 100 nM. The practical application of the proposed nanosensor has been validated with lake water, tap water and seawater samples.