Screening of silver nanoparticles in antibacterial products by leveraging a silver nanowire membrane as a filter and amplifier

The wide application of consumer goods containing silver nanoparticles (AgNPs) inevitably increases the accumulation of AgNPs in the environment and human exposure risk, which leads to an urgent need for accurate and efficient analytical methods to detect AgNPs. Herein, we proposed a filtration-based SERS method for sensitive and selective analysis of AgNPs. By adding Raman probe molecules (4-amino thiophenol) that can bind the surface of AgNPs, AgNPs can be identified by the characteristic signal of the probe and AgNP complexes. To improve the detection ability, an iodide-modified silver nanowire (AgNWs) membrane was chosen as a filter to separate and enrich AgNPs. Meanwhile, the signal intensity can be amplified due to the electromagnetic field interaction between AgNPs and AgNWs. Different types of AgNPs (coated with citrate, hydroxylamine hydrochloride and polyvinylpyrrolidone) can be detected and identified from other Ag species by the proposed method. Raman mapping was also performed on the membrane to obtain the distribution information of citrate-AgNPs with concentrations from 10−1 to 10−6 mg mL−1. A linear relationship (R2 = 0.998) between signal intensity and citrate-AgNP concentration indicates the possibility of quantification. Furthermore, AgNPs in antibacterial products without purification were successfully and efficiently detected by the proposed method. This work demonstrated the ability of the filtration-based SERS platform for analysing trace AgNPs in consumer goods.