Multifunctional SERS\nSubstrate for Simultaneous Detection\nof Multiple Contaminants and Photothermal Removal of Pathogenic Bacteria

In this work, a boric-acid-modified Fe<sub>3</sub>O<sub>4</sub>@Au@BA-MOF composite material as a multifunctional SERS substrate\nwas ingeniously constructed for detecting both pathogens and antibiotics\nas well as photothermally inactivating the pathogens. Through improving\nthe dispersity and stability of gold nanoparticles (Au NPs), leveraging\nthe specificity of boric acid (BA) groups in recognizing cis-diol\nstructures, and the ability of SERS technology to provide unique fingerprint\nspectra of targets, the sensitive and stable detection of pathogens\nand antibiotics was achieved. Compared with Au NPs and Fe<sub>3</sub>O<sub>4</sub>@Au, the SERS enhancement factor of Fe<sub>3</sub>O<sub>4</sub>@Au@BA-MOF was 4.31 × 10<sup>6</sup>, which was about\n400 times and 16 times higher than the former two, respectively. Among\nthe existing work, the limit of detection for pathogens was lower\nor comparable, and it exhibited good stability, maintaining consistent\nperformance for 23 days. Additionally, this substrate achieved efficient\nphotothermal inactivation of pathogens under both near-infrared light\nand natural light excitation. Within 8 min of near-infrared light\nirradiation, the bactericidal rates for <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> reach 100% and 99.3%, respectively.