Visual monitoring of polystyrene nanoplastics < 100 nm in drinking water based on functionalized gold nanoparticles

Abstract

Nanoplastics (NPLs), of which polystyrene (PS) plastics are typical representatives, are of global concern as emerging contaminants, especially the leakage of NPLs into drinking water, which is directly related to human health. To onsite visually assess the extent of NPLs contamination in drinking water in a rapid and non-destructive manner, this work extends the application of the highly sensitive response to pH of mercaptoundecanoic acid (MUA)-functionalized gold nanoparticles (Au NPs). Further, a visual sensing method based on the binding of alkyl chains to PS NPLs with hydrophobic force to suppress pH-induced aggregation of functionalized nanoparticles was constructed. Particularly, the designed analytical strategy is a significant renewal of the first strategy for the visual detection of PS NPLs, featuring non-destructive, fast response (∼30 s), high selectivity, and detection limit (26 μg/L). Importantly, it can reliably distinguish the more hazardous PS NPLs of smaller particle size (<100 nm). Moreover, visualization-based detection observes the color change of the reaction solution from dark purple to wine red. The employment of a smartphone installed App to read the color three-channel value R further ensures the credibility of the analysis results. The proposed visual analysis strategy will provide a promising new avenue for efficient detection of surface hydrophobic NPLs and further evaluation of their particle size or shape.