This review describes recent advances in the use of magnetic-plasmonic particles (MPPs) for bacteria detection by Surface-Enhanced Raman Scattering (SERS). Pathogenic bacteria pollution has always been a major threat to human health and safety. SERS spectroscopy has emerged as a powerful and promising technique for sensitive and selective detection of pathogen bacteria. MPPs are considered as a versatile SERS platform for their excellent plasmonic properties and good magnetic responsiveness. Improved preparation method and typical characterization technique of MPPs are introduced, focusing on the thin and continuous metallic shell covering process. Consequently, the SERS-based sensing methods for bacteria identification were discussed, including the label-free and label-based methods. Finally, an overview of the current state of the field and our perspective on future development directions are given.

A new high-performance surface-enhanced Raman scattering (SERS) substrate with extremely high SERS activity was produced. This SERS substrate combines the advantages of Au film over nanosphere (AuFON) substrate and Ag nanoparticles (AgNPs). A three order enhancement of SERS was observed when Rhodamine 6G (R6G) was used as a probe molecule to compare the SERS effects of the new substrate and commonly used AuFON substrate. These new SERS substrates can detect R6G down to 1 nM. The new substrate was also utilized to detect melamine, and the limit of detection (LOD) is 1 ppb. A linear relationship was also observed between the SERS intensity at Raman peak 682 cm⁻¹ and the logarithm of melamine concentrations ranging from 10 ppm to 1 ppb. This ultrasensitive SERS substrate is a promising tool for detecting trace chemical molecules because of its simple and effective fabrication procedure, high sensitivity and high reproducibility of the SERS effect.

Repeatable fabrication of sensitive plasmonic substrates through a simple procedure has become a major challenge for SERS-based sensing and imaging. Herein, a new class of high-performance SERS substrates, including pyramid, ridged-hexagon, and quasi-triangle nanostructures, is successfully fabricated based on the nanosphere lithography technique and anisotropic wet etching. Using the wafer-scale Cr-hole array as the etching mask, cavity-templates of various configurations are fabricated by the orientation-dependent wet etching technique, from where the nanostructure arrays are finally peeled-off. The anisotropic wet etching on (100), (110), and (111) silicon wafers has been systematically studied at the nanoscale revealing the formation mechanism of these cavity-templates. The peeled-off nanostructure arrays provide high-density tips and/or gaps (about 2.5 × 10⁷ mm⁻²) and thus facilitate the generation of “hot spots”. The distribution of the electromagnetic field is visualized by the finite difference time domain calculation. And the calculation results are validated by SERS characterization. The SERS enhancement factors of these substrates are in the order of 10⁶–10⁷, with the maximum enhancement factor of 1.32 × 10⁷ yielded by the ridged-hexagon arrays. The proposed nanostructure arrays present excellent homogeneity and reproducibility (with the largest relative standard deviation of 16.43%) for the reason that the SERS-active substrates are peeled-off from an identical template. The cost-effective fabrication, high sensitivity, good homogeneity and well-performed reproducibility demonstrate that these orientation-dependent NSs are good candidates for SERS-based in vitro and in situ detection and biosensing.