Intellectualized Visualization of Single-Particle Raman Spectra for Sensitive Detection and Simultaneous Multianalysis of Heavy Metal Ions

Easy-to-use, reliable, and real-time methods for detecting heavy metal ion contamination are urgently required, which is a primary concern for water pollution control and human health. However, present methods for this aim are still unable to achieve simultaneous multianalysis for complex real sample detection. Herein, an intellectualized vision-based single-nanoparticle Raman imaging strategy combined with ion-responsive functional nucleic acids (FNAs) was proposed to address these issues. We reported a correspondence between the concentration of the analytes and the density of particles (DOP) of specifically captured nanoparticles to achieve sensitive detection and simultaneous multianalysis of heavy metal ions. The specific detection of Pb2+ (Hg2+) was obtained with a detection linear range from 100 pM to 100 nM (from 500 fM to 100 nM) and limit of detections low to 1 pM (100 fM), with the advantages of good specificity, excellent homogeneity, and reproducibility. Furthermore, the differentiation of different heavy metal ions (Pb2+/Hg2+) was achieved, i.e., the simultaneous multianalysis, based on Raman imaging of the single particle and intelligent machine vision method. Finally, the Raman imaging assay was utilized for real sample analysis, and it provided a powerful and reliable tool for detecting trace Pb2+/Hg2+ in real water samples and facilitated the portable on-site monitoring of heavy metal ions.