Rapid and Early Detection of Bacteremia and In Situ Elimination by Graphene Hybrid Terahertz Metasurfaces with CuS Nanoparticles

Currently, clinical culture methods for bacterial detection suffer from a long detection time and low sensitivity, which are insufficient to satisfy the requirements for rapid diagnosis of bacteremia. Here, we fabricated terahertz metal-graphene hybrid metasurfaces (THz MGHM) coupled with polyethylenimine-modified CuS nanoparticles (PEI@CuS NPs) for ultrasensitive detection and in situ inactivation of pathogenic bacteria. To obtain a strong light localization effect based on the bound state in the continuum (BIC), the MGHM consists of a symmetry-broken complementary metal elliptical hole array and a monolayer of graphene covering the surface. Both experimental and simulation approaches were employed to investigate the feasibility and enhancement mechanisms of PEI@CuS NPs in MGHM biosensing. The intense electron transfer between the PEI@CuS NPs and MGHM triggered obvious changes in the graphene's conductivity, which led to a significant change in the quasi-BIC (QBIC) resonance. With the assistance of this THz signal amplifier, the boronic-acid-group-functionalized MGHM was embedded into a poly(methylpentene) (TPX) microfluidic device, which achieved selective capture and sensitive detection of bacteria with limits of detection (LODs) between 11 and 14 CFU/mL for different species. Subsequently, the system accomplished in situ inactivation of bacteria through the synergistic effect of the dual photothermal effect and the generation of reactive oxygen species (ROS). Notably, the THz MGHM platform exhibited time-to-positivity (TTP) for bacteremia patients earlier than traditional blood culture did by an average of 5 h and enabled timely sterilization, which provides a strategy for rapid warning of bacteremia and prevention of dissemination risk for potential clinical applications.