Exploring the dermal safety of green-synthesized Ag–TiO2 nanocomposites for topical applications†

We investigated Ag–TiO₂ nanocomposites (NCs) synthesized using leaf extracts of Azadirachta indica and Mangifera indica for topical applications. The Ag–TiO₂ NCs were first characterized by their spherical shapes, with sizes ranging from 20–26 nm to 5–6 nm, and a zeta potential value between −27 and −23 mV. DLS analysis revealed average particle sizes of 671 nm and 573 nm for Ag–TiO₂ NCs synthesized from A. indica and M. indica, respectively. The MICs of the nanocomposites were determined via dilution in both Gram-positive and Gram-negative bacteria to determine the optimal concentration for dermal applications. The cytotoxicity assay (MTT) of ATN and ATM compounds at MICs of 312.5 μg mL⁻¹, 625 μg mL⁻¹, and 1250 μg mL⁻¹ showed that they were nontoxic to fibroblast cells. Further assessments of acute and subacute dermal safety were conducted on Charles Foster rats with NCs applied at 625 μg mL⁻¹, 3125 μg mL⁻¹, and 6250 μg mL⁻¹ concentrations. Observations were made for any signs of dermal toxicity using behavioural and physical indices. In acute dermal toxicity, the NCs were applied once, and in subacute dermal toxicity, NCs were applied once daily for 28 days and observed for any sign of dermal toxicity using observation indices like behavioural changes, edema scores, and erythema scores. Post-experiment analyses of body weight, serum biochemistry, oxidative stress, and hematological profiles revealed that the nanocomposites exhibited significant antimicrobial activity. Notably, the safety evaluations indicated no adverse changes, suggesting these NCs are well-tolerated for dermal applications and show great promise for future topical applications.