SERS signal unification strategy: Preparation of AuNPs@4-MBA and its quantitative detection in mixed lactic acid bacteria

Abstract

In order to realize rapid identification of different species of lactic acid bacteria and rapid quantitative detection of mixed lactic acid bacteria. In this study, L. plantarum Y1 and P. pentosaceus Z1 were used as research subjects, and AuNPs@4-MBA was prepared as the SERS substrate material for the acquisition of SERS spectra of different species of lactic acid bacteria and the construction of taxonomic identification models and SERS digitized quantitative equations. The results showed that the enhancement factor of AuNPs to 4-MBA was 3.08 × 10², and the reproducibility was excellent (RSD < 10 %). With AuNPs@4-MBA as the base material, the differences of SERS peaks between L. plantarum Y1 and P. pentosaceus Z1 could be clearly distinguished. Principal component analysis (PCA) and cluster analysis (LDA) could completely visually classify and identify different species of lactic acid bacteria. The SERS quantitative equation y = 7509.32×-5942.69, R² = 0.99 and the detection limit lower than 10 CFU/mL was determined by the construction of SERS detection and quantitative model for different ratios and concentrations of mixed lactic acid bacteria. In the complex environment matrix, the detection accuracy of mixed lactic acid bacteria by this method reached 96.34 % to 103.54 %. It provides a promising technical strategy for rapid qualitative and real-time quantitative monitoring of mixed lactic acid bacteria.