Sensitive and specific detection of clinical bacteria: Via vancomycin-modified Fe₃O₄@Au nanoparticles and aptamer-functionalized SERS tags

A sensitive surface-enhanced Raman scattering (SERS) platform for the simultaneous detection of two pathogenic bacteria on the basis of dual recognition by vancomycin and aptamers is reported for the first time, using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as target bacteria. This dual-recognition platform was developed using vancomycin-modified Fe₃O₄@Au magnetic nanoparticles (Fe₃O₄@Au-Van MNPs) for broad-spectrum recognition and efficient bacterial enrichment, and aptamer-functionalized SERS tags for the specific and sensitive quantification of target bacteria in authentic specimens. Our results showed that the Fe₃O₄@Au-Van MNPs allow the rapid capture of bacteria from complex solutions with a capture efficiency as high as 88.89% for S. aureus and 74.96% for E. coli within 15 min. The limits of detection (LODs) of the platform were found to be 20 and 50 cells mL^-1 for S. aureus and E. coli, respectively, and favorable linear relations were observed between the logarithm of bacterial concentration and the SERS intensity at the characteristic Raman peaks. The high specificity and potential clinical applications of the technique were also proven. Our method elucidated novel advances and potential applications in the field of multiple SERS detection of pathogens.