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

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 Cu 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 10 to 10 CFU mL, with a limit of detection (LOD) of 10 CFU mL. 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.