Development of perceptive multi-analyte sensing platform based on fluorescent CdS QDs for selective and sensitive assay of virulent contaminants in aqueous medium

Abstract

Relentless discharge of organic pollutants into the aqueous realm, including antibiotics, pesticides and nitroaromatic explosives, has necessitated world-wide attention for trace level monitoring of organic pollutants to safeguard water resources. This work aims to develop a multi-analyte fluorescent probe based on the biocompatible chitosan capped CdS QDs (CTS-CdS QDs) for the detection of environmentally deleterious organic pollutants. The facile aqueous chemical approach was opted for the fabrication of CTS-CdS QDs and their structural and morphological features were effectually evinced by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). The distinct fluorescent characteristics of CTS-CdS QDs showed an unprecedented selectivity towards nitrophenolic explosives (p-nitrophenol (PNP), 2,4-dinitrophenol (2,4-DNP), picric acid (PA)), fluoroquinolones (ofloxacin (OLX), nor-ofloxacin (NOLX), levofloxacin (LVX)) and organochlorine pesticide (dicofol (DCF)) in waste water. Moreover, extremely low limit of detection was attained by CTS-CdS QDs for each detected analyte i.e., PNP (7.6 µM), 2,4-DNP (3.5 µM), PA (4.2 µM), OLX (0.006 µM), NOLX (0.026 µM), LVX (0.084 µM) and DCF (0.24 µM). Benefiting the outstanding characters of fluorescent probe in terms of high sensitivity, long fluorescent stability, quick response to targeted analytes, these were also successfully employed for trace level detection of organic pollutants in real samples analysis and excellent recoveries of 90–105% were achieved for spiked water samples. Through this work, green CTS-CdS QDs has been reported first time for the detection of nitrophenolic explosives, fluoroquinolone antibiotics and DCF pesticide in aqueous samples using a single probe.