Identification and Quantification of Multiple Pathogenic <i>Escherichia coli</i> Strains Based on a Plasmonic Sensor Array

Pathogenic <i>Escherichia coli</i> (<i>E. coli</i>) is a widespread and clinically significant foodborne pathogen. Due to its high mutation rates and phenotypic diversity, rapid identification of its subtypes remains challenging and prone to false positives when detecting single strains. In this study, we developed a plasmonic sensor array with high-dimensional signal readouts (ζ-potential, dynamic light-scattering (DLS), surface-enhanced Raman scattering (SERS), and ultraviolet-visible (UV-vis) absorption spectra) for the selective discrimination of pathogenic <i>E. coli</i>, integrated with bacterial culture methods. The plasmonic sensor units demonstrated strong encoding capabilities, facilitating the differentiation of subtle variations among various <i>E. coli</i> strains and showing excellent anti-interference performance. The array realized different pathogenic <i>E. coli</i> strains, bacterial mixture identification, and even quantitative detection. Remarkably, the working concentration for the sensor array was notably low, at 10⁴ CFU/mL. Finally, by incorporating bacterial isolation culture, the designed sensor array obtained 100% accuracy in detecting <i>E. coli</i> in real food samples. These findings highlight the sensor array's potential for applications in food safety monitoring and clinical diagnostics, offering a sensitive, rapid, and reliable tool for pathogen detection in complex samples.