Available on-demand - S.NM04.03.03
A Highly Selective Sensor Based on Fluorescent Fe2O3-CdSe Nanocomposite for Detection and Removal of Picric Acid
Vishal Kumar1,Soumitra Satapathi1
Indian Institute of Technology Roorkee1
Detection of the nitro-fragrant compound at trace level is critical in combating terrorism, for keeping up national security and for providing environmental and clinical safety. Among various nitroaromatics compounds (NACs), the importance of picric acid (PA) owe to its extensive usage in the manufacture of rocket fuels, fireworks, deadly explosives, leather processing and sensitizers in photographic emulsions. As of now, many fluorescence chemosensors/probes have been effectively applied for the detection of PA with functional specificity based on its characteristic properties, particularly resonance energy transfer and electron-deficient nature of the nitro group (-NO2), yet only a few appeared closer to the practical applications. Late reports on CdSe nanoparticles and expedient to surface modification showed its fate in the detection of NACs. Quantum dots have a clear advantage over molecule-based emitters; however, these multi-model sensors are inconvenient for the removal of the target species, which might cause secondary contamination. Towards this end, the incorporation of a fluorescent and magnetic functionality in a single nanocomposite particle would be a promising alternative.
Here, we present a methodology and promising novel hybrid nano-structure that comprises of magnetic core encapsulated inside a thin silica shell (Fe2O3@SiO2 NPs), electrostatically adsorbed through the free anionic carboxyl group with a positively charged spacer arm of florescent Cysteamine-capped CdSe quantum dot (QD) (particle size ≈ 12.7 nm). This multimodal nanosensor provides an efficient sensitive and selectivity detection of PA over a number of other explosive (NACs) in DMSO, (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 which was found to be a mixture of immediate dynamic and static quenching as the lifetime of nanosensor (0.98 ns) is reduced to 0.63 in presence of PA. In addition to solution-phase sensing, this magneto-fluorescent nanosensor also showed an excellent ability for the removal of detected PA molecules with the use of an external magnet, staging as a possibility for the potential application of low-cost and stand-off sensor. In summary, this elegant architecture results in an ultra-small magneto-fluorescent nanoparticle offering a novel platform for the development of a field-based PA sensor.
1. Abbasi, F. et. al. Spectrochim Acta A. 2019, 216, 230-5.
2. Sun, X. et. al. Chem. Soc. Rev. 2015,44,8019-8061.