Effect of subcutaneous application of chlorhexidine nanocapsules on local microvascularization in rats

Objective: To evaluate the effects of subcutaneous application of chlorhexidine-containing nanocapsules (N_CLX) on local microvascularization and inflammatory response in rats. Methods: Thirty Wistar rats were divided into five groups (n=6): saline solution (control), pure chlorhexidine (CLX), nanocapsules without chlorhexidine (Nano 0), nanocapsules with chlorhexidine (Nano CLX), and formalin 1% (positive control). Each received 0.1 mL subcutaneous injections. Laser-Doppler flowmetry measured microvascular blood flow, erythrocyte concentration, and skin temperature at baseline, 3, 6, and 24 hours. Histological analysis assessed collagen fibers, fibroblast proliferation, and inflammation. Results: N_CLX and CLX groups showed no significant alterations in blood flow, erythrocyte concentration, or skin temperature compared to control (p>0.05), while formalin increased all parameters (p<0.05). Histological analysis revealed slight fibroblast proliferation and collagen deposition in N_CLX, indicating moderate inflammation and tissue repair. Fibroblast density and collagen differed significantly between N_CLX and formalin groups (p<0.05). Conclusion: N_CLX induced a mild inflammatory response without affecting microcirculation, confirming its biocompatibility. These findings support its potential for controlled drug delivery in localized therapies.