Identification of polystyrene nanoplastics using surface enhanced Raman spectroscopy

There is clear evidence that micro- and nanoplastics are accumulating in the environment, and their increasing concern of potential harm to wildlife has been identified as a major global issue. However, identification of nanoplastics in environmental samples remains a great challenge, and thus highlighting the great need for new approach. Herein, for the first time, we show that surface enhanced Raman spectroscopy (SERS) offered a feasible approach to identify trace polystyrene (PS) nanoplastics, which is the most produced nanoplastics and also widely presented in the natural environment. We found that when PS nanoplastics were surrounded by SERS-active silver nanoparticles (AgNPs), a set of Raman spectra with chemical information could be obtained via SERS mapping. This map showed the potential PS distribution of the nanoplastics on a silicon wafer, allowing a quick and detailed analysis of the nanoplastics. Moreover, the proposed method was able to identify previously undetectable plastic particles as small as ~50 nm spiked in real water, demonstrating the power of SERS to probe nanoplastics. Our work is thus an important step in nanoplastic research, and we believe that this approach can be further developed to study the occurrence, formation, and transports of nanoplastics in the natural environment.