SERS-based AgNWs-AuNRs@Ag composite substrate SERS substrate chips for rapid and sensitive simultaneous detection of microplastics

Microplastics are defined as plastic particles with a size < 5 mm. Due to their small size, difficulty in degradation, and large specific surface area, microplastics are capable of persisting in the environment for extended periods and of adsorbing and releasing toxic substances. Consequently, there is a pressing need for an accurate, rapid, and sensitive method for detecting microplastics. We have established a SERS-based strategy for microplastic detection via co-assembly of dual substrates, AgNWs and AuNRs@Ag, onto a hydrophilic glass sheet to prepare an AgNWs-AuNRs@Ag composite substrate SERS substrate chips. Mutual assembly of the dual substrates gives rise to nest-like morphology, which contributes to increasing the interfacial contact area between microplastics and substrates, thereby improving sensitivity and stability. The detection of the two microplastics, PS and PE, demonstrated good linearity, with ranges of 1 × 10 -3 g/mL to 1 × 10 -8 g/mL and 1 × 10 -3 g/mL to 5 × 10 -9 g/mL, respectively. The simultaneous detection of two batches of PS and PE with different concentrations was achieved with a CV < 15% and an MRE < 10%, exhibiting good precision and accuracy. The method provides a new technical reference for the detection of microplastics.