Fluorescent Fe2O3-CdSe nanocomposite probe for selective detection and removal of picric acid

Abstract

Here, we present a methodology and promising novel hybrid nano-structure that comprises of magnetic core encapsulated inside a thin silica shell, electrostatically adsorbed with a positively charged spacer arm of fluorescent Cysteamine-capped CdSe quantum dots (QDs). This multimodal nanosensor provides an efficient, sensitive and selective detection of Picric Acid (PA) (LOD ≈ 2.2 μM) (Quenching constant KPA ≈ 4.3 × 104 M−1) in solution via photo-induced electron transfer mechanism. The sensing mechanism is probed via UV–Vis spectroscopy, steady-state and time-resolved fluorescence spectroscopy. The removal of PA, attached to the spherical magnetic core-shell particles, is achieved using an external magnet. This elegant architecture results in an ultra-small magneto-fluorescent nanoparticle (particle size ≈ 12.7 nm), offering a novel platform for the development of a field-based PA sensor. This strategy is having the potential for applications in the field of low-cost and stand-off sensor.