Hydrophobic interaction enables rapid enrichment of volatile metabolites on Au/TiO2 based SERS substrates for ultrasensitive bacteria detection

Abstract

Bacterial contamination in diets is a major threat to human health and a global health problem. The development of sensitive methods for rapid discrimination of benign and pathogenic bacteria is essential. Herein, using self-standing Au/TiO₂ nanotubes as a surface-enhanced Raman spectroscopy (SERS) substrate, rapid and sensitive bacteria discrimination is achieved via the hydrophobic interaction between the volatile metabolites released from pathogenic bacteria and the SERS substrate. With the modification of hydrocarbon moieties, the SERS substrate demonstrates improved binding ability and rapid enrichment performance towards volatile metabolites through the hydrophobic interaction. The metabolites enriched on the hytocarbon moieties then drive the replacements of Raman probes from the SERS substrate, as demonstrated by the remarkably decreased Raman signals in the silent region (1800–2800 cm⁻¹). Using Escherichia coli (E. coli) as the model pathogenic bacteria, the SERS platform exhibits good discrimination ability between benign and pathogenic bacteria within 4 min and allows detection of E. coli at a level of as few as 3 × 10⁰ cells per mL. Considering that volatile metabolites are associated with the activity of bacteria, this technique can be further applied as a guide for antibiotic treatment, demonstrating reliable and rapid guidance for interrelated bacteria therapy.