SERS Imaging and ICP-MS quantification of the biological uptake of nanoplastics using a dual-detectable model material

Nanoplastics (NPs) pose significant concerns to human health due to their wide environmental presence and high potential for biological uptake, transport, and accumulation. Conventional analytical methods for studying NP-bio interactions suffer from low accuracy and precision due to their limited reliability and quantitative capability. To address these challenges, we developed a dual-detectable NP material that allows for in-situ imaging by surface-enhanced Raman spectroscopy (SERS) and ex-situ quantification by inductively coupled plasma-mass spectrometry (ICP-MS). In this study, we developed a model NP that has a core-shell structure with Raman reporter-functionalized gold nanoparticles as the core and a layer of plastic as the shell. The model polystyrene (PS) NPs demonstrated stability in structure, morphology, size, and surface charges over one year, with no indication of chemical leaching. The model NPs also remained stable in suspension over 24 hours without precipitation observed. A single model NP was successfully detected by SERS, indicating the single-particle detection capability of this approach. Further, garlic plants were used as our biological model to evaluate the potential of using the dual-mode detectable model NPs to study NP-bio interactions. To determine whether the model NPs in the garlic plants could be effectively detected, garlic plants were grown in various concentrations of model NP suspensions for a 30-day period. The detection results showed that the NP uptake was concentration-dependent, with higher concentrations of model NPs leading to higher uptake by the garlic roots. The uptake of PS NPs by garlic plants occurred primarily in the roots. The study also investigated the changes in NP uptake over time, which demonstrated that longer NP exposure resulted in more NP uptake in garlic roots. ICP-MS quantification confirmed the presence of model NPs in roots rather than in the upper parts of the plant, with higher concentrations of model NP suspensions leading to greater root uptake. This dual-mode detectable model NPs have high potential for studying the biological uptake, transport, and accumulation of NPs qualitatively via SERS and quantitatively via ICP-MS, which holds significant implications for better understanding their biological behavior and impacts on living organisms (e.g., crops) in future studies.