Size-dependent selectivity and quantification on detecting PS nanoplastics particles in a mixed solution with different diameters by using periodic Ag nanocavities SERS substrates with high sensitivity.

Nanoplastic particles (NPPs) have attracted lots of attention due to their toxicity. In this study, a Surface-enhanced Raman scattering (SERS)-based category on selectivity and quantification detecting the polystyrene (PS) NPPs has been presented. Firstly, the size-dependent SERS relationship between the diameter of Ag nanocavities (AgNCAs) and the diameter of the PS NPPs is studied. By continuously dripping the PS NPPs on proposed AgNCAs substrates, AgNCAs exhibit excellent enrichment capability with a promoted limit of detection (LOD) of 0.001 mg/mL. Secondly, thermally evaporated Ag nanoparticles (AgNPs) as an enhancement layer are used to form the AgNPs/PS NPPs/AgNCAs sandwich structure with a SERS enhancement of 300 %. Thirdly, a SERS microfluidic chip constructed by integrating two kinds of pore size (87 nm and 356 nm) AgNCAs is fabricated to selectivity quantifying absolute concentration of the mixed PS NPPs with different diameters in a mixed solution. It shows excellent performance. This novel category proves a good method for identifying plastic nanoparticles and analyzing their size distribution existing in the surroundings indicating good practical applications.