Ligand chemistry of gold, silver and copper nanoparticles for visual read-out assay of pesticides: A review

Metal nanoparticles have garnered a significant interest in various fields of science because of their remarkable optical properties, and they have shown a great impact in improving the sensitivity of UV–Visible spectrometry, just like as expensive analytical instruments. Modifications of metal nanoparticles (Au, Ag and Cu) with specific ligands have shown great potentiality to establish miniaturized colorimetric assay of wide variety molecules, offering the quantification of trace level target analytes via the color changes, which could be noticed with naked-eye. The interface between the ligand chemistry of metal nanoparticles and trace level pesticides leads to the specific covalent and non-covalent interactions, thereby causing a significant color change in the metal nanoparticles via the aggregation of metal nanoparticles induced by pesticides. In this review, the role of ligand chemistry on the surfaces of metal nanoparticles (Au, Ag and Cu) for colorimetric detection of various pesticides is summarized. This review briefly illustrates the aggregation mechanisms involving in the colorimetric detection of pesticides using functionalized metal nanoparticles as colorimetric sensors. Further, this review also summarizes the used ligands on the surfaces of metal nanoparticles (Au, Ag and Cu) for visual readouts of various pesticides at minimal volumes of samples. Finally, we outline the challenges and future perspectives of ligand chemistry on metal nanoparticles for colorimetric assays of pesticides from various samples.