Versatile spiky spindle-shaped copper-based nanocomposites: A SERS substrate for discrimination, quantification and inactivation of multiple bacteria

Abstract

Designing a multi-functional strategy that integrates rapid and sensitive detection of pathogenic bacteria and efficient antibacterial activity is of great significance. Here, we reported a smart triple-functional spindle shape copper-based nanocomposites, obtaining the remarkable surface-enhanced Raman scattering (SERS) enhancement, and its spikes at both ends with physical piercing ability cooperate with Ag⁺ and Cu²⁺ releasing capability endowed it with robust antibacterial effectiveness. Originally, gold-core silver-shell nanoparticles (Au@Ag NPs) with excellent SERS performance were loaded onto the spindle shape copper-methylimidazole nanoparticles (Cu-MIM) under electrostatic action, obtaining Au@Ag/Cu-MIM nanocomposites. The SERS sandwich nanostructure bacteria/4-mercaptophenylboronic acid (4-MPBA)/Au@Ag/Cu-MIM was fabricated utilizing the unique bacterial “fingerprints” generated through the introduction of bifunctional 4-MPBA, which served as both a SERS label and internal standard. Two different bacteria (E. coli and S. aureus) were highly sensitively discriminated and quantified in the concentration range spanning from 10¹ to 10⁷ CFU mL⁻¹, with a limit of detection (LOD) of 10 CFU mL⁻¹. The SERS probe under investigation demonstrated its efficacy in human blood samples, exhibiting sensitive discrimination of various bacteria. Meanwhile, 40 μg/mL Au@Ag/Cu-MIM exhibited extraordinary antibacterial activity, the survival rate of S. aureus was 0.15 %, while E. coli was 0.8 %. Furthermore, Au@Ag/Cu-MIM effectively destroyed biofilm, reducing its content to 30 % of the control group after 3 h of treatment. Our work successfully integrated triple-function, which includes specific discrimination, sensitive quantification, and inactivation of multiple bacteria.