Surface-enhanced Raman scattering (SERS) is a powerful analytical tool for detecting trace pollutants due to its molecular fingerprint specificity and single-molecule sensitivity. However, conventional two-dimensional gap-enhanced substrates suffer from limited analyte diffusion into nanogap caused by plasmonic material hydrophobicity. Herein, we present a V-shaped SERS substrate designed to overcome these challenges through three synergistic mechanisms: (i) three-dimensional (3D) plasmonic nanogaps, (ii) gravity-driven analyte enrichment enabling efficient aqueous-phase molecule transport, and (iii) light-trapping nanopores amplifying electromagnetic fields. By utilizing atomic layer deposition (ALD)-defined ultrathin alumina sacrificial layers, we achieved precisely tunable nanogaps (2–10 nm) between gold nanoparticles (AuNPs) and the underlying gold film (Au) within V-shaped architectures. The optimized 6 nm AuNPs-gap-Au nanostructure balances near-field intensity and aqueous analyte accessibility, achieving sub-nanomolar sensitivity for rhodamine 6G with outstanding reproducibility (RSD < 9 % across 10 −9 –10 −5 M). Significantly, the substrate enables multiplex detection of dye pollutants (basic blue 3, malachite green, methylene blue) at sub-nanomolar level in river water, showing great potential for real-time, on-site monitoring of emerging pollutants in natural water systems.
Juan Liu,Yangyang Liu,Yunyun Zhang,Xuejun Ruan,Hanyun Cheng,Qiuyue Ge,Liwu Zhang
Bioaerosols pose a great threat to human life and health, and developing highly efficient and accurate identification and analysis methodologies for bioaerosols provides prerequisite knowledge to evaluate their toxicity on human health. In this paper, a rapid and economical method is proposed for the detection of bioaerosols based on surface-enhanced Raman scattering (SERS). The SERS substrate was prepared using an anodic aluminum oxide (AAO) template with an inverted conical (V-shaped) nanopore array structure that was subsequently deposited with Ag nanoparticles (AgNPs) through magnetron sputtering. This tailored nanostructure essentially enables the differentiated and efficient detection of Escherichia coli and Staphylococcus epidermidis health risks within 10 min, along with corresponding detection limits of 103 cells/mL and 104 cells/mL, respectively. Notably, by comparing the Raman spectrum of the two bacteria obtained from the plain plane deposited with the same AgNPs, the V-shaped nanopore array structure provides a more robust enhancement effect in the Raman signal relative to the ordinary plane. More importantly, the applicability of developed AgNPs@V-shaped AAO SERS substrate was validated using ambient bioaerosols, thus emphasizing the great potential of the application of SERS-based technique for a cost-effective, rapid label-free and culture-free bioaerosol analysis without experiencing conventional time-consuming and laborious incubation processes.
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