Quaternized Molecular Brush‐Grafted Injectable Microgel with Anti‐Inflammatory and Drainage Properties for Efficient Therapy of Anal Fistula

Anal fistula is a common disease with recurrent inflammation and accumulated exudate. Traditional treatments often fail to effectively eliminate inflammation and ensure adequate drainage, leading to prolonged healing time and a high recurrence rate. Herein, a new class of quaternized molecular brush-grafted injectable microgel (denoted as GAA@CNT-g-PVBTMA) is developed through thermal polymerization and mechanical fragmentation to promote the healing process of anal fistula. Benefiting from the fragmented morphology with a porous structure, the microgel can effectively fill the fistula and facilitate the drainage of exudate. Owing to the electrostatic interactions between the positively charged quaternized carbon nanotube molecular brush (CNT-g-PVBTMA) and the negatively charged inflammatory cytokines, GAA@CNT-g-PVBTMA microgel exhibits excellent anti-inflammatory properties with scavenging rates of 92.6% for tumor necrosis factor-α (TNF-α) and 92.5% for interleukin-1β (IL-1β). Rat inflammatory anal fistula model demonstrates that the microgel can effectively reduce inflammation and epithelialization of the fistula, thereby promoting the healing of the anal fistula. By integrating effective filling, adequate drainage, and excellent anti-inflammatory properties, GAA@CNT-g-PVBTMA microgel provides a promising new direction for the treatment of anal fistula.