Herein, we propose a novel "low-background" biosensing platform integrating magnetic separation and hybridization chain reaction (HCR) for signal amplification, enabling ratiometric colorimetric detection and visual observation of S. typhimurium. In the presence of S. typhimurium, specific aptamer recognition triggers the HCR to couple the urease-labeled DNA to the HCR reporting system, ultimately generating a ratiometric colorimetric response upon enrichment by Fe3O4@PDA@PEI and magnetic separation. The assay demonstrates excellent sensitivity, achieving a detection limit of 2.34 CFU mL-1. Simultaneously, the ratiometric sensor enables direct visual detection of S. typhimurium at concentrations as low as 103 CFU mL-1. Furthermore, leveraging the photothermal properties of Fe3O4@PDA@PEI under 808 nm NIR irradiation significantly reduced S. typhimurium viability, thereby minimizing the risk of secondary contamination. Recovery rates of 84.2%-115.3% in common spiked food samples containing S. typhimurium confirm its practicality. This integrated "detection and inactivation" strategy offers a proactive defense for food safety.
The rise of multidrug‐resistant bacterial infections and biofilms poses a significant challenge to wound healing. Herein, we developed a temperature‐responsive gel–sol phase‐transition multifunctional hydrogel, named CPAM/GS, by incorporating a novel nanozyme, CeO2@PtAu@Mn2(CO)10, into a gelatin/sodium alginate matrix. The synthesized CeO2@PtAu@Mn2(CO)10 nanozyme exhibits multi‐enzyme activities, including peroxidase‐, oxidase‐, and catalase‐like properties, enabling it to generate ROS in response to the pH of the infected microenvironment and supply oxygen under hypoxic conditions. The CPAM/GS hydrogel demonstrates excellent photothermal performance (η = 47.99%) and allows on‐demand release of carbon monoxide (CO) and nanozymes upon NIR irradiation. In vitro experiments confirmed its potent antibacterial efficacy against methicillin‐resistant Staphylococcus aureus and Pseudomonas aeruginosa through the synergistic effects of photothermal therapy, chemodynamic therapy, and CO gas therapy, achieving a 100% and 99.8% antibacterial rate under NIR irradiation. Furthermore, this hydrogel effectively disrupts preformed biofilms, suppresses virulence gene expression, and promotes cell migration. In a mouse model of MRSA‐infected wounds, treatment with CPAM/GS hydrogel‐NIR(+) significantly accelerated wound healing, eliminated bacteria, and modulated wound microenvironment by reducing pro‐inflammatory cytokines and promoting angiogenesis. Its excellent biosafety and hemostatic performance were also confirmed. This work proposes a multifunctional synergistic strategy for treating multidrug‐resistant bacterial infections and promoting wound regeneration.
Ting Du, Meng Wang, Xixuan Chen et al.· Advanced Healthcare Material...· 0 citations