Tandem copper and gold nanoclusters for two-color ratiometric explosives detection.

We report a sensory platform for the determination of common explosive species (e.g., TNT, PETN, RDX) based on the differential response from two different luminescent metal nanoclusters. In particular, whereas the red emission from bovine serum albumin-protected gold nanoclusters was strongly quenched by nitro-, nitrate-, and nitroamine-containing explosive organic molecules, blue-emitting glutathione-capped copper nanoclusters proved inert to quenching by these same analytes, instead showing evidence for aggregation-induced emission enhancement (AIEE). As a result, this discrete gold/copper nanocluster pairing provides a dual-probe, ratiometric (red-to-blue) system signaling the presence of TNT and other common explosives. This strategy opens up new potential for nanocluster-based analyte signaling, with implications to fluorescence resonance energy transfer (FRET) strategies as well.