Conjugated Polymer Composite Flexible Wood Hydrogel‐Mediated Sequential NIR‐II Photothermal and Photodynamic Anti‐Bacteria and Macrophage Polarization for Acute Sinusitis

ABSTRACT Bacterial infection‐induced acute sinusitis is prevalent and can easily progress into chronic sinusitis, which is often difficult to treat due to the challenging nature of the site, increased environmental pollution, and bacterial drug resistance prevalent nowadays. To address these challenges, a flexible hydrogel (LM@P/S@CP@Hemin) that involves flexible wood‐modified logs, photoactive conjugated polymers, an immunomodulator, and an immobilization hydrogel was prepared for nasal cavity treatment. The flexible wood‐modified logs provide mechanical strength support. In vitro, experiments verified that the hydrogel could efficiently induce the photothermal effect under near‐infrared‐II laser irradiation after deeply penetrating bone and produce reactive oxygen species (ROS) to initiate the photodynamic effect for synergetically eliminating bacteria. The introduction of hemin endows LM@P/S@CP@Hemin hydrogel with a strong immunomodulatory effect on macrophages to achieve anti‐inflammation and cellular ROS clearance abilities, which avoids the excessive oxidative stress in the nasal cavity. The results showed that the hydrogel induced an anti‐bacterial effect with a 98.5% inhibition rate against methicillin‐resistant Staphylococcus aureus, hadexcellent clearance ability of excessive ROS, and promoted anti‐inflammatory M2 macrophage generation to relieve inflammation. Meanwhile, transcriptome sequencing and mRNA level measurements revealed that the hydrogel could regulate inflammatory‐related genes. In vivo, bacterial infection‐induced acute sinusitis rabbit model experiments and histological analysis further confirmed the great therapeutic effect of LM@P/S@CP@Hemin for acute sinusitis based on photothermal and photodynamic therapy. Therefore, LM@P/S@CP@Hemin is an excellent therapeutic material that can adapt to the nasal environment and treat acute sinusitis.