A novel SERS and colorimetry synergistic strategy for rapid bacterial detection

Abstract

Surface-enhanced Raman spectroscopy (SERS) has been extensively researched in bacterial detection due to its rapid nature. However, in practical applications, signal instability can easily lead to result deviations. Particularly in quantitative detection, the uneven spatial distribution of plasmonic “hotspots” and the non-uniform distribution of samples in the substrate can affect signal intensity, resulting in unreliable detection. The quantitative process is complex and challenging. To address this issue, this study proposes a novel strategy for bacterial detection that combines SERS with colorimetry. The method involves labeling bacteria using 4-MPBA@AuNPs. The labeled samples are qualitatively detected through SERS by being dropped onto a PTFE filter membrane and quantitatively analyzed through colorimetry by adding a NaCl solution. Four typical bacterial strains are chosen to validate the integrated method. The findings demonstrate its efficacy in facilitating qualitative bacterial analysis within the range of 10¹–10⁸ CFU mL⁻¹. Moreover, the method allows for preliminary concentration quantification, achieving precise detection within the 10⁴–10⁸ CFU mL⁻¹ range. The innovative aspect of this study lies in the development of a novel synergistic detection strategy, integrating SERS qualitative analysis with colorimetric quantitative analysis. This approach maximizes the advantages of both techniques by enabling simultaneous qualitative and quantitative detection of bacteria on a universal substrate. It enhances the operational efficiency and result reliability of bacterial detection in real-world applications while retaining its inherent speed.