A Protein Fibril and Carboxylated Cellulose Nanofibril Gel Enhances Quercetin Delivery for Intestinal Barrier Protection in DSS-Induced Intestinal Barrier Injury

The intestinal barrier-protective efficacy of quercetin (Que) is limited by its poor gastrointestinal stability and insufficient bioaccessibility. To overcome this, we engineered a dual-fibril gel delivery system for Que, termed QTC, through the assembly of tiger-nut protein fibrils and carboxylated cellulose nanofibrils. In the DSS-induced intestinal barrier injury mouse model, QTC outperformed free Que in preserving intestinal mucosal architecture and mitigating epithelial damage. It markedly restored intestinal barrier integrity, reflected by the upregulation of tight-junction proteins and reduced intestinal permeability. Furthermore, QTC effectively suppressed inflammatory responses and oxidative stress, thereby maintaining barrier homeostasis. Notably, QTC intervention positively modulated the gut microbiota, enriching for beneficial genera and boosting short-chain fatty acid production. Collectively, our findings demonstrate that the novel QTC gel significantly amplified the intestinal barrier-protective effects of Que. This study provides an effective food-grade delivery strategy to enhance the efficacy of polyphenols for gut health management.