〔Abstract〕 Objective To investigate the effects ofa dual-functional cationic nucleic acid nanodelivery system (DCNA) loaded with small interfering RNA targeting Bruton’s tyrosine kinase (siBTK) on the immune-inflammatory microenvironment of periodontitis by regulating BTK expression. Methods DCNAsiBTK was prepared using a double-emulsion solvent evaporation method, and its physicochemical properties and sustained-release performance were characterized. Cytotoxicity was evaluated using the Cell Counting Kit-8 (CCK-8) assay. Antibacterial activity against periodontal pathogens was assessed by colony-forming assays. BTK mRNA and protein expression levels were determined by quantitative real-time PCR (qRT-PCR) and Western blotting, respectively. Enzyme-linked immunosorbent assay (ELISA) was performed to quantify the levels of inflammatory cytokines, including IL-1β, IL-6, and TNF-α . A murine periodontitis model was established and treated with DCNAsiBTK. Therapeutic efficacy and biosafety were evaluated using qPCR, micro-computed tomography (micro-CT), hematoxylin-eosin (HE) staining, and immunohistochemistry (IHC). Results Stable DCNAsiBTK nanoparticles with an average particle size of (168.8 ± 2.2) nm and a zeta potential of (17.9 ± 0.8) mV were successfully prepared. Transmission electron microscopy (TEM) revealed uniformly spherical morphology with favorable sustained-release properties. CCK-8 assays demonstrated no significant cytotoxicity of DCNAsiBTK within the concentration range of 0-100 nmol/L. In vitro studies showed that DCNAsiBTK effectively inhibited the growth of Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), and Fusobacterium nucleatum (Fn), indicating broad-spectrum antibacterial activity. qRT- PCR and Western blotting analyses demonstrated that DCNAsiBTK downregulated BTK mRNA and protein expression in a dose-dependent manner. ELISA results showed that DCNAsiBTK significantly reduced the secretion of IL-1β, IL-6, and TNF-α, thereby attenuating inflammatory responses. In vivo experiments further demonstrated that DCNAsiBTK suppressed anaerobic bacterial proliferation within periodontal pockets, alleviated alveolar bone resorption and periodontal inflammation, and caused no obvious pathological damage in major organs, including the heart, liver, spleen, lungs, and kidneys. Conclusion DCNAsiBTK efficiently encapsulated and released siBTK, and exhibited dual antibacterial and anti-inflammatory activities. By suppressing BTK expression, DCNAsiBTK effectively attenuated the progression of periodontitis, providing a promising novel strategy for adjunctive periodontal therapy.