Layer-by-layer assembled quercetin-lysozyme-pectin nanoparticles alleviate high-fat diet-induced intestinal injury through gut microbiota modulation in Drosophila melanogaster

LBL-assembled MPN-LYS-PEC nanoparticles enable microbiota-targeted quercetin delivery. • The nanoparticles show high quercetin encapsulation and structural stability. • The nanoparticles alleviate HFD-induced intestinal injury in D. melanogaster . • Germ-free assays confirm a gut microbiota-dependent protective mechanism. Quercetin is a bioactive flavonoid; however, its poor stability and low bioavailability limit its protective effect against intestinal injury. To address this limitation, quercetin-Fe 2 + metal-phenolic network (MPN) nanocores are constructed using a solvent exchange method, followed by layer-by-layer electrostatic assembly with positively charged lysozyme (LYS) and negatively charged pectin (PEC) to form ternary MPN-LYS-PEC nanoparticles. Comprehensive physicochemical characterization confirms effective charge regulation and structural stability throughout the assembly process, together with a high quercetin encapsulation efficiency (92.57 ± 0.67%) and loading efficiency (25.98 ± 2.59%). The multilayered architecture further protects quercetin during gastrointestinal digestion, enabling microbiota-targeted delivery. In a high-fat diet (HFD)-induced female and male Drosophila melanogaster ( D. melanogaster ), the nanoparticles effectively reduced intestinal leakage, cell death, and oxidative stress, and improved metabolic dysregulation. They also beneficially reshaped gut microbiota by enriching Commensalibacter and reducing Novosphingobium . Importantly, experiments in germ‑free D. melanogaster further demonstrate that the gut‑protective effects induced by MPN‑LYS‑PEC nanoparticles are associated with the gut microbiota. Collectively, these findings establish the self-assembled MPN-LYS-PEC nanoparticle as an effective strategy for gut microbiota-targeted quercetin delivery, thereby alleviating HFD-induced intestinal injury and restoring metabolic homeostasis. Download: Download high-res image (184KB) Download: Download full-size image