Non-Invasive Real-Time Evaluation of Antimicrobial Effects of Biomaterials Through In Vivo Bacterial Tracking

Currently, the evaluation of in vivo antimicrobial efficacy predominantly relies on endpoint detection methods, such as Colony Forming Units (CFU) counting and histopathological staining following animal sacrifice, to assess the antimicrobial properties of materials. These traditional detection methods struggle to capture real-time changes in infection status during treatment. This study proposes a novel strategy utilizing lipophilic near-infrared dye (e.g., DIR, [1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide]) for bacterial fluorescent labeling, combined with In Vivo Imaging System (IVIS) technology, to achieve real-time monitoring of dynamic changes in bacterial infection in localized infection models. Following local injection of stained bacteria, IVIS imaging revealed temporal changes in fluorescence signals within infected areas, which were further utilized to evaluate the in vivo efficacy of antimicrobial biomaterials. We have effectively validated this approach in a rat bone defect infection model. Additionally, this method can be used in conjunction with micro-CT to enable three-dimensional observation. Experimental results demonstrate that this approach intuitively reflects the immediate effects of antimicrobial treatment and facilitates precise quantitative analysis, providing technical support for in vivo detection of antimicrobial efficacy.