Selectively Tracking Nanoparticles in Aquatic Plant Using Core–Shell Nanoparticle-Enhanced Raman Spectroscopy Imaging

Nanoparticles contribute to enormous environmental processes, but, due to analytical challenges, the understanding of nanoparticle fate remains elusive in complex environmental matrices. To address the challenge, a core–shell nanoparticle-enhanced Raman spectroscopy (CSNERS) imaging method was developed to selectively track prevalent SiO2 nanoparticles in an aquatic plant, Lemna minor. By encapsulating gold nanoparticles and Raman reporters inside, the resonance Raman signature was enhanced, thus enabling the sensitive and selective detection of SiO2 nanoparticles at an environmentally relevant concentration. The panoramic visualization of the translocation pathway of nanoparticles shows an unexpected, fast (in hours) and a preferential accumulation of nanoparticles on the node, leaf edge, root cap, etc., implying the ability of CSNERS to spectroscopically determine nanotoxicity. The core–shell design in CSNERS was capable of multiplex labeling two differently charged nanoparticles and distinguishing their biobehavior simultaneously. Meanwhile, the CSNERS method can be further applied for a variety of nanoparticles, implying its promising applications for nanotoxicity research and biogeochemical study.