Nanozymes are considered to represent a new era of antibacterial agents, while their antibacterial efficiency is limited by the increasing tissue depth of infection. To address this issue, here, we report a copper and silk fibroin (Cu-SF) complex strategy to synthesize alternative copper single-atom nanozymes (SAzymes) with atomically dispersed copper sites anchored on ultrathin 2D porous N-doped carbon nanosheets (CuN _x -CNS) and tunable N coordination numbers in the CuN _x sites ( x = 2 or 4). The CuN _x -CNS SAzymes inherently possess triple peroxidase (POD)-, catalase (CAT)-, and oxidase (OXD)-like activities, facilitating the conversion of H ₂ O ₂ and O ₂ into reactive oxygen species (ROS) through parallel POD- and OXD-like or cascaded CAT- and OXD-like reactions. Compared to CuN ₂ -CNS, tailoring the N coordination number from 2 to 4 endows the SAzyme (CuN ₄ -CNS) with higher multienzyme activities due to its superior electron structure and lower energy barrier. Meanwhile, CuN _x -CNS display strong absorption in the second near-infrared (NIR-II) biowindow with deeper tissue penetration, offering NIR-II-responsive enhanced ROS generation and photothermal treatment in deep tissues. The in vitro and in vivo results demonstrate that the optimal CuN ₄ -CNS can effectively inhibit multidrug-resistant bacteria and eliminate stubborn biofilms, thus exhibiting high therapeutic efficacy in both superficial skin wound and deep implant-related biofilm infections.

In recent years, along with the rapid development of relevant biological fields, there has been a tremendous motivation to combine molecular imprinting technology (MIT) with biosensing. In this situation, bioprobes and biosensors based on molecularly imprinted polymers (MIPs) have emerged as a reliable candidate for a comprehensive range of applications, from biomolecule detection to drug tracking. Unlike their precursors such as classic immunosensors based on antibody binding and natural receptor elements, MIPs create complementary cavities with stronger binding affinity, while their intrinsic artificial polymers facilitate their use in harsh environments. The major objective of this work is to review recent MIP bioprobes and biosensors, especially those used for biomolecules and drugs. In this review, MIP bioprobes and biosensors are categorized by sensing method, including optical sensing, electrochemical sensing, gravimetric sensing and magnetic sensing, respectively. The working mechanism(s) of each sensing method are thoroughly discussed. Moreover, this work aims to present the cutting-edge structures and modifiers offering higher properties and performances, and clearly point out recent efforts dedicated to introduce multi-sensing and multi-functional MIP bioprobes and biosensors applicable to interdisciplinary fields.

It is urgent to find an effective and convenient method to detect and kill microbial strains due to the threat of pathogenic bacterial infection and the low effectiveness of antibiotics. In the present work, a dual-functional peptide coupling gold nanoconjugate (Au@P937 NRs) was facilely fabricated by conjugating an adhesion peptide (WGLHTSATNLYLHGGGC, P937) with Au nanorods (Au NRs), of which the peptide P937 was designed by the phage display biopanning technology and showed specific binding affinity to bacteria. After the modification of P937, the longitudinal surface plasmon resonance (LSPR) absorbance peak of the Au@P937 NRs was found to be very sensitive to the variation of bacterial concentration. The Au@P937 NRs exhibited enhanced NIR-based photothermal conversion efficiency. Moreover, the Au@P937 NRs exhibited good biocompatibility. Hence, the Au@P937 NRs could be used as a dual-functional nanoconjugate for the detection and photothermal ablation of bacteria. For the bacterial detection by the Au@P937 NRs, the detection limit could reach 46 cfu mL⁻¹ for E. coli and 89 cfu mL⁻¹ for S. aureus, respectively. Both E. coli and S. aureus could be killed completely in 10 min by the Au@P937 NRs under 808 nm laser irradiation. This work provided a facile, convenient and effective strategy for detecting and sterilizing bacteria.