A Nile Red-assisted colorimetric and SERS dual-mode strategy for the rapid and highly sensitive detection of nanoplastics.

BACKGROUND

Nanoplastics are progressively recognized as a significant global pollutant and a severe threat to human health. Owing to their tiny particle size and low environmental concentrations, nanoplastics detection currently relies on sophisticated laboratory instrumentation. Colorimetric assays represent a rapid, user-friendly strategy, as the testing results can be readily identified by the naked eye. However, this technique is generally limited by unsatisfactory detection sensitivity. Surface-enhanced Raman scattering (SERS) technique allows for the highly sensitive analysis of samples in aqueous solutions without direct contact. Nevertheless, the complicated preparation of high-performance SERS substrates greatly hinders their practical application in nanoplastics detection.

RESULTS

Herein, a novel colorimetric/SERS dual-mode sensing strategy was developed via Nile Red labeling for rapid and sensitive detection of nanoplastics (≥100 nm). Nanoplastics labeled with Nile Red (referred to as NPs@NR) demonstrated a visually discernible coloration to the naked eye, as well as an obvious SERS signal under a portable Raman spectrometer. Moreover, the SERS signal of NPs@NR was collected from a straightforward SERS substrate with an RSD of 9.93% that fabricated by transferring Ag nanoparticles film (ANF) onto the end of a hydrophilic polyvinylidene fluoride (PVDF) strip in one step. Colorimetric assays were capable of qualitative identification and quantitative detection of NPs@NR at a concentration of 10 μg/mL and higher. Furthermore, the ANF-based SERS substrate achieved a low limit of detection (LOD) of 0.01 μg/mL toward NPs@NR. More importantly, the proposed colorimetric/SERS dual-mode strategy presented excellent feasibility for the detection of nanoplastics spiked in real environmental samples.

SIGNIFICANCE: Given integrating the advantages of facile detection through colorimetric analysis and highly sensitive trace assays using SERS, the proposed dual-mode method demonstrates potential for on-site monitoring of nanoplastics in aquatic environments.