A highly sensitive fluorescence assay for 2,4,6-trinitrotoluene using amine-capped silicon quantum dots as a probe

We present a simple and effective fluorescence method for the detection of 2,4,6-trinitrotoluene (TNT), which is based on TNT recognition by amine-capped silicon quantum dots (SiQDs). The highly luminescent functionalized SiQDs were obtained by a one-step hydrothermal process, using 3-aminopropyltrimethoxysilane as the precursor. The as-prepared SiQDs were directly used as a recognition probe for the detection of TNT because of the strong interactions between the TNT molecule and the SiQDs with an amine group. The formation of Meisenheimer complexes (TNT-amine complexes) could quench the fluorescence of SiQDs by fluorescence resonance energy transfer. Such fluorescence response could be used to quantify TNT over the range of 5-500 nM with a detection limit down to 1 nM, and has been successfully applied for the assay of TNT in spiked tap water. The probe exhibited excellent selectivity. This method has great potential for applications in TNT detection.