Chitosan/selenium nanoparticles Pickering emulsion prolong quercetin retention time to ameliorates cognitive disorder: Focus on restoring the metabolic disorder and gut microbiota.

Gut microbiota influence brain inflammation and cognitive impairment by regulating lipid metabolism. The therapeutic efficacy of quercetin (Que) in Alzheimer's disease (AD) treatment is significantly limited by its poor water solubility and short residence time in vivo. Herein, Chitosan (CS) modified selenium nanoparticles was used to prepare a high-loading Pickering emulsion (Que-CS/Se-PE), improving bioaccessibility of Que. Simulated gastrointestinal fluid experiments demonstrate that Que-CS/Se-PE exhibits strong stability under acidic conditions. In vitro digestion studies indicate that Que-CS/Se-PE enables QUE to target intestinal fluids and release slowly. In vivo imaging revealed that the gastrointestinal retention time of Que-CS/Se-PE was up to 48 h. In HFD + D-gal-induced mice, Que-CS/Se-PE treatment reduced serum TC and brain TNF-α levels by 40.8 % and 31.5 %, respectively, indicating substantial improvement in lipid metabolism and neuroinflammation. Behavioral tests showed that Que-CS/Se-PE improved cognitive performance, with preference index elevated by 2.1-fold. Moreover, the relative abundances of Akkermansia, Lactobacillus, and Bacteroidota increased by 2.7-, 17.8-, and 4.7-fold, respectively. In conclusion, Que-CS/Se-PE exhibits interfacial stability, excellent adhesion, and sustained-release properties, significantly prolonging the retention time of quercetin in vivo and enhancing its bioavailability. Furthermore, it modulates lipid metabolism and gut microbiota, and finally ameliorates cognitive impairment in obesity and age-related AD.