A Hybrid Quantum Dot−Antibody Fragment Fluorescence Resonance Energy Transfer-Based TNT Sensor

TLDR

The study develops a solution‑phase nanoscale FRET sensor that uses luminescent quantum dots conjugated to anti‑TNT antibody fragments to specifically detect TNT in aqueous environments. The sensor couples anti‑TNT fragments to hydrophilic QDs via metal‑affinity coordination, quenches QD photoluminescence with a dye‑labeled TNT analogue through proximity‑induced FRET, and restores fluorescence when soluble TNT displaces the analogue, yielding a concentration‑dependent signal.

Abstract

We demonstrate the use of luminescent QDs conjugated to antibody fragments to develop solution-phase nanoscale sensing assemblies, based on fluorescence resonance energy transfer (FRET) for the specific detection of the explosive 2,4,6-trinitrotoluene (TNT) in aqueous environments. The hybrid sensor consists of anti-TNT specific antibody fragments attached to a hydrophilic QD via metal-affinity coordination. A dye-labeled TNT analogue prebound in the antibody binding site quenches the QD photoluminescence via proximity-induced FRET. Analysis of the data collected at increasing dye-labeled analogue to QD ratios provided an insight into understanding how the antibody fragments self-assemble on the QD. Addition of soluble TNT displaces the dye-labeled analogue, eliminating FRET and resulting in a concentration-dependent recovery of QD photoluminescence. Sensor performance and specificity were evaluated.