Nano-in-microalgae integrated modular hydrogel system for spatiotemporally targeted oral gene therapy of ulcerative colitis.

Small interfering RNAs (siRNAs) have brought revolutionary advances as promising therapeutic candidates for ulcerative colitis, owing to the durable anti-inflammatory efficacy and favorable biocompatibility. Nevertheless, the clinical translation of oral siRNA therapeutics remains hindered by the harsh conditions of the gastrointestinal tract. Thus, a colon-specific modular hydrogel platform (IG@SP@FK LNPs@siTNFα) was engineered through integration of microalgal biotechnology and nanomedicines. The system comprised three functionally components: (i) a cathepsin B/glutathione (GSH) dual-responsive gemini-like cationic MA-FK-SS lipid nanoparticles core encapsulating tumor necrosis factor-α siRNA (FK LNPs@siTNFα); (ii) a negatively charged Spirulina (SP) intermediate layer (SP@FK LNPs@siTNFα); and (iii) an outer inulin-derived hydrogel (IG) coating. The IG layer provided robust protection against harsh gastrointestinal conditions and regulated the gut microbiota homeostasis. Subsequent colonic degradation of IG triggered site-specific release of SP@FK LNPs@siTNFα, which exhibited enhanced mucosal adhesion through the intrinsic helical architecture of SP. Notably, FK LNPs@siTNFα demonstrated efficient cellular internalization, proton-sponge effect-driven endosomal escape and dual-responsive siRNA release, ultimately silencing the expression of TNF-α. IG@SP@FK LNPs@siTNFα significantly attenuated the progression of ulcerative colitis via suppression of pro-inflammatory cytokine cascades (IL-6, IL-1β, TNF-α), restoration of intestinal barrier integrity, and normalization of gut microbiota homeostasis. This nano-biohybrid system established a paradigm for oral nucleic acid delivery, combining spatiotemporal control and multi-mechanistic intervention for precise gene therapy of ulcerative colitis.