An injectable carboxymethyl chitosan–polyaniline/oxidized dextran triple-network hydrogel for long-term gastrointestinal tissue marking and photothermal tumor therapy

This study presents a novel carboxymethyl chitosan-polyaniline/oxidized dextran (CMCS-PANI/OD) hydrogel specifically designed for gastrointestinal tissue marking in endoscopic procedures. The hydrogel addresses key limitations of existing marking agents, including sedimentation, leakage, and short marking durations, while providing enhanced biocompatibility, injectability, and stability. Synthesized using Schiff base linkages and amide bonds, this polysaccharide-polymer hybrid structure demonstrates exceptional performance under physiological conditions. Its photothermal conversion properties enable dual functionalities, facilitating precise lesion localization and effective tumor ablation under near-infrared laser irradiation. Comprehensive <i>in vitro</i> and <i>in vivo</i> evaluations confirm its safety, biocompatibility, and hemocompatibility, and studies of injectability reveal seamless application <i>via</i> a standard and endoscopic syringe. The CMCS-PANI/OD hydrogel maintains its <i>in vivo</i> marking stability for up to 120 days, significantly outperforming conventional agents. These results suggest that the CMCS-PANI/OD hydrogel offers a cost-effective, versatile, and highly promising solution for minimally invasive gastrointestinal procedures and oncological therapies.