Triple-Function Au-Ag-Stuffed Nanopancakes for SERS Detection,Discrimination, and Inactivation of Multiple Bacteria

New strategies combining sensitive pathogenic bacterial detection and highantimicrobial efficacy are urgently desirable. Here, we report smart triple-functional Au-Ag-stuffed nanopancakes (AAS-NPs) exhibiting (1) controllably oxidative Ag-etching thicknessfor simultaneously obtaining the best surface-enhanced Raman scattering (SERS) enhance-ment and high Ag-loading antibacterial drug delivery, (2) expressive Ag+-accelerated releasingcapability under neutral phosphate-buffered saline (PBS) (pH similar to 7.4) stimulus and robustantibacterial effectiveness involving sustainable Ag+release, and (3) three-in-one featurescombining specific discrimination, sensitive detection, and inactivation of different pathogenicbacteria. Originally, AAS-NPs were synthesized by particle growth of the selective Ag-etchedAu@Ag nanoparticles with K3[Fe(CN)6], followed by the formation of an unstable Prussianblue analogue for specifically binding with bacteria through the cyano group. Using specificbacterial"fingerprints"resulting from the introduction of dual-function 4-mercaptophenylbor-onic acid (4-MPBA, serving as both the SERS tag and internal standard) and a SERS sandwichnanostructure that was made of bacteria/SERS tags/AAS-NPs, three bacteria (E. coli,S. aureus,andP. aeruginosa) were highly sensitively discriminated and detected, with a limit of detection of 7 CFU mL-1. Meanwhile, AAS-NPs killed 99% of 1x105CFU mL-1bacteria within 60 min under PBS (pH similar to 7.4) pretreatment. Antibacterial activities of PBS-stimulated AAS-NPs againstS. aureus,E. coli,andP. aeruginosawere extraordinarily increased by 64-fold, 72-fold, and 72-fold versusPBS-untreated AAS-NPs, respectively. The multiple functions of PBS-stimulated AAS-NPs were validated by bacterial sensing,inactivation in human blood samples, and bacterial biofilm disruption. Our work exhibits an effective strategy for simultaneousbacterial sensing and inactivation.