**Background:** Periodontitis is an inflammatory disease of the supporting structures of the teeth caused by microorganisms, leading to loss of periodontal ligament and alveolar bone. Non-surgical periodontal therapy, including scaling and root planing, is essential, and local drug delivery agents such as hydrogels are used as adjuvants. Ocimum sanctum Linn (Tulsi) has documented antimicrobial, anti-inflammatory, and antioxidant properties. Sorbitol, a sugar alcohol, and carboxymethylcellulose (CMC), a natural polymer, are biocompatible and can enhance hydrogel properties. This study aimed to formulate a hydrogel combining these components and evaluate its physicochemical characteristics for potential use in periodontitis.
**Methods:** An ethanolic extract of Ocimum sanctum Linn was prepared by macerating 50 g of Tulsi powder in 1000 mL of ethyl alcohol for 48 hours, filtering, and evaporating at 65°C for 30 minutes to obtain a supercritical fluid. The hydrogel was prepared by soaking Carbopol in purified water with 0.2% w/v sodium benzoate overnight, then mixing with a CMC solution containing propylene glycol and 2 mL of Tulsi extract. Triethanolamine was added to neutralize pH. Separately, 2 g of CMC was dissolved in 100 mL distilled water and refrigerated for 24 hours. Then, 0.5 g of sorbitol was combined with 0.5 g of Ocimum sanctum gel, mixed with 100 mL of CMC solution, and refrigerated for 24 hours. Thirty mL of this mixture was placed in petri dishes at 37°C overnight. The swelling index was measured by placing 10 mg of freeze-dried hydrogel in 100 µL of phosphate-buffered solution (PBS) at 37°C, weighing at intervals up to 84 hours, and calculating swelling ratio as ((w2-w1)/w1) × 100%. In vitro drug release was assessed by dissolving 5 mg of hydrogel in 1 mL PBS at 37°C with mechanical agitation; 1 mL samples were collected at intervals and replaced with fresh PBS, and absorbance was measured at 450 nm using a UV spectrophotometer. Contact angle was measured using a K100 Force Tensiometer with advancing and receding angles. Atomic force microscopy (AFM) was performed using NANOSURF C3000 to assess surface roughness and particle size.
**Key Results:** The swelling index at 1 hour, 6 hours, and 84 hours was 11.1%, 13.7%, and 15.8%, respectively, indicating rapid initial swelling that stabilized after 6 hours, suggesting minimal degradation. In vitro drug release showed a burst release of 90-100 nM over the first 3 days, followed by sustained release of 200-210 nM from day 4 to day 13, another burst release of 250-280 nM from day 14 to day 17, and sustained release of 300 nM from day 18 to day 20. The contact angle was 72.81° on the left and 75.99° on the right, confirming hydrophilicity (angle <90°). AFM revealed a surface roughness of 119.32 nm, with 80% of particles in the range of 50-71 µm and a mean particle size of 51 µm. No particle breakage was observed over 20 days.
**Clinical Implications:** The hydrogel's sustained release profile over 20 days, hydrophilicity, and stable swelling index suggest it could provide prolonged local drug delivery in periodontal pockets, potentially reducing inflammation and promoting tissue regeneration. The particle size (50-71 µm) is within the optimal range for intra-articular injection in rats (35-105 µm) as per prior studies, indicating low toxicity for gingival tissues. The use of natural, non-toxic components (Tulsi, sorbitol, CMC) makes this formulation an economical and biocompatible alternative for non-surgical periodontal therapy. However, further in vivo and clinical studies are required to confirm efficacy and safety in periodontitis patients.