Photo-driven Surfactant-Free Gold Nanostars for Rapid Bacterial Detection in Food Safety Using Surface-Enhanced Raman Spectroscopy

Traditional foodborne bacterial detection methods have limitations, driving the need for advanced techniques like surface-enhanced Raman spectroscopy (SERS), known for its high sensitivity, specificity, and nondestructive analysis in food safety. However, SERS faces challenges regarding substrate sensitivity and complex sample preparation. This study presents an innovative photo-driven method for synthesizing surfactant-free anisotropic gold nanoparticles for SERS applications. These gold nanostars, with unique morphology and superior SERS performance, are used for sensitive Escherichia coli (E. coli) detection in complex food samples. Gold nanostar synthesis, controlled by the pH, reaction time, and HAuCl4 concentration, results in enhanced SERS capabilities. For in situ indole separation, a metabolic product of E. coli and the detection target, we introduce a miniaturized array gas membrane separation device. The SERS-based E. coli detection method exhibits remarkable sensitivity, with a 5 cfu/mL limit of detection and reliability within a 100–800 cfu/mL concentration range.