Localized surface plasmonic resonance nanosensor based on the agglomeration of gold nanoparticles for the detection of ciprofloxacin in wastewater.

Gold nanoparticles (AuNPs) demonstrates a unique localized surface plasmonic resonance (LSPR) characteristic compared to their bulk counterpart. Plasmonic properties are useful in environmental monitoring (EM) shown by their successful application in simple and fast detection of emerging contaminants (i.e., pharmaceuticals via colorimetric and spectrometric assays. Ciprofloxacin (CIP) is a common antibiotic used to treat bacterial infections in humans and animals. Therefore, its vast application is responsible for its inevitable presence in hospital and household effluents leading to its occurrence in the environment. Hence, this study is proposing a simple, rapid, and sensitive colorimetric nanosensor for detecting and quantifying CIP in wastewater using UV-Vis spectroscopy. The presence of CIP induces the aggregation of citrate-capped AuNPs, due to its higher affinity tothe nitrogen present on CIP compared to the carboxylate of the citrate cap. This phenomenon destabilizes the AuNPs, by eliminating the electrostatic hindrance and ensures the agglomeration of the AuNPs. A color modulation of red to blue visually detects the change in the parameter, accompanied by an LSPR peak shift. The developed method displays an excellent linear relationship in the range of 0.1 – 2.0 µM (R²=0.98), with a lower limit of detection (LOD) and quantification (LOQ) of 0.39 µM and 1.2 µM, respectively. The analysis of spiked wastewater samples suggests that the method can detect a low concentration of the CIP in environmental matrices. [ABSTRACT FROM AUTHOR]