A filter-like AuNPs@MS SERS substrate for Staphylococcus aureus detection

• SERS filter-like substrate made of AuNPs embedded in mesoporous silica (denoted as AuNPs@MS) was applied for SERS applications.
• Staphylococcus aureus can be concentrated on the filter-like AuNPs@MS substrates within a few seconds.
• SERS spectra showed more characteristic peaks with significant enhancement on the spectra signals.
• Highly reproducible SERS spectra can be obtained from the substrate.
• About 900 times of SERS enhancement can be achieved (Au wt%=16) compared with Raman spectra obtained from the pure mesoporous silica (Au wt%=0).

An accurate, highly sensitive and rapid identification assay of cells is extremely important in areas such as medical diagnosis, biological research, and environmental monitoring. Laboratory examinations of clinical isolates require time-consuming and complex processes to identify the colony count, with approximately 106–108 cells needed for the characterization of strains. In the present study, a highly sensitive SERS filter-like substrate is prepared with AuNPs embedded in mesoporous silica (denoted as AuNPs@MS) synthesized by a simple one-spot method, and an example of its use for the filtration and concentration of analytes from aqueous samples is reported. In an application for Staphylococcus aureus SERS discrimination, the results show that the target cells can be concentrated on the filter-like AuNPs@MS substrates within a few seconds, with much better reproducibility with regard to the SERS spectra that are obtained. The experimental findings suggest that the AuNPs@MS substrate supports much higher intensity with more distinguishable peaks compared to Au/Cr-coated substrate, and the reproducibility is also significantly improved. The substrates investigated in this study generated 900 times more SERS signals at a concentration of 106 CFU/mL in the detection of S. aureus on mesoporous silica (Au wt%=0) when using AuNPs@MS with 16 wt% AuNPs. The limitation of this filter-like SERS substrate can be applicable for small volume samples (few to hundred microliter).