Imaging and quantifying the biological uptake and distribution of nanoplastics using a dual-functional model material

Nanoplastics (NPs) are invisible to human eyes yet pose significant concerns to human health due to their wide environmental presence and high potential for biological uptake, transport, and accumulation. Conventional analytical methods suffer from low accuracy and precision in NP detection due to their limited reliability and quantitative ability. To address these challenges, we developed a dual-functional model NP 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, the model NP has a core-shell structure with Raman reporter-functionalized gold nanoparticles as the core and a layer of plastic as the shell. The gold core can enhance the Raman reporter signals and make model PS detectable, which can be used to visualize the uptake of the model NP in plant tissue by SERS. Meanwhile, the model NP particle numbers in the collected plants can be quantified by ICP-MS based on the presence of gold in the core. The model PS demonstrated stability in structure, size, and surface charges over one year, with no indication of chemical leaching. In this study, garlic plants were used as our experimental matrix to evaluate the potential of the dual-functional model PS for application in living organisms. Our aim was to determine whether the model PS in the garlic plants could be effectively quantified and qualified by SERS and ICP-MS. Garlic plants were grown in various concentrations of model NP suspensions for a 30-day period. The results showed that the NP uptake was concentration-dependent with higher concentrations of model NP leading to higher uptake by the garlic roots. The study also investigated the changes in NP uptake over time, showing that longer NP exposure resulted in more NP uptake in garlic roots. The study also demonstrated the effective coordination between SERS and ICP-MS. In cases where SERS had limitations in detecting the presence of model PS, ICP-MS proved capable of facilitating detection in garlic tissue. This study demonstrates the potential use of this dual-functional model NP for studying NP behavior with SERS and ICP-MS in living organisms, which holds significant implications for better understanding their impact on crops for future studies.