Formulation, development & Evaluation of Calcium carbonate silver nanogel in Rheumatoid arthritis

AbstractRheumatoid arthritis (RA) is a chronic, systemic autoimmune inflammatory disorder characterized byprogressive joint destruction, synovial inflammation, and bone erosion. Current treatment paradigms relyheavily on systemic disease-modifying antirheumatic drugs (DMARDs) and biologic agents, which arelimited by severe systemic toxicity, incomplete therapeutic response, and an inability to halt localized jointdamage. This study presents the formulation, architectural optimization, and in vitro biologicalevaluation of a novel hybrid nanotherapeutic delivery vehicle: a calcium carbonate–silver nanoparticlecomposite embedded within a biocompatible hyaluronic acid nanogel matrix (HA-NG5). Calciumcarbonate nanoparticles (CCNPs) were precipitated under strict conditions to yield the highly porousvaterite polymorph, offering local pH-buffering and mineralization support to seal the "bone protectiongap". Concurrently, silver nanoparticles (AgNPs) biosynthesized using Azadirachta indica provided amulti-target antimicrobial profile and potent anti-inflammatory properties via the suppression ofmacrophage activation.Using a Quality by Design (QbD) / Factorial Design model, the optimized HA-NG5 formulationdemonstrated excellent physicochemical characteristics, including a nanoscale particle size ($<250$ nm),uniform distribution, acceptable polydispersity, high entrapment efficiency ($>80%$), and dynamicviscoelastic properties suitable for intra-articular and localized topical retention. Dynamic ion-releaseassays verified a highly tunable, pH-responsive liberation profile for both Ca²⁺ andAg⁺ ions, adapting to the acidic microenvironment (pH 5.5–6.5) typical of arthritic joints.Biological assays confirmed remarkable hemocompatibility ($<5%$ hemolysis), excellentcytocompatibility ($>93%$ cell viability), extensive biofilm disruption (70--84% inhibition)against Staphylococcus aureus and MRSA, and significant suppression of nitric oxide (NO) generation inlipopolysaccharide-stimulated macrophages. These findings indicate that the developed hybrid nanogelsystem provides a robust, multimodal therapeutic alternative for localized joint therapy, successfullymerging structural tissue protection with targeted immunomodulation and antimicrobial prophylaxis.