Biofabrication of Silver Nanoparticles with Feijoa Sellowiana Tailored by Box-Behnken Design: an Eco-Friendly Approach to Enhance Antifungal Properties in Children's Toothpaste

Oral candidiasis and its association with dental caries necessitate the development of toothpaste with enhanced antifungal properties, particularly for children at high risk of infection. This study aims to investigate the antifungal efficacy of children's toothpaste incorporating biosynthesized silver nanoparticles (AgNPs) using Feijoa sellowiana. Silver fluoride and Feijoa leaf extract were used for the synthesis of AgNPs. The independent variables were the concentration of AgF, pH of the extract, and temperature. The optimized formula was obtained using Design Expert software and Box-Benken design. The physicochemical properties of AgNPs were evaluated by UV-absorption wavelength measurements, SEM, and TEM analyses. Finally, the powder of optimized AgNPs was added to Colgate Kids Toothpaste (R) and its antifungal effect was evaluated using the standard agar well diffusion method. The optimization process identified an AgF concentration of 8 mM, a pH value of 9.56, and a temperature of 58 C-degrees as influential factors for the formulation. The optimized AgNPs exhibited a size of 42.75 nm, and SEM and TEM analyses confirmed their spherical shape. Both toothpaste formulations, with and without AgNPs, demonstrated antifungal activity. Although the antifungal effect of both toothpaste types against Candida glabrata did not show a significant difference (p > 0.088), the toothpaste containing AgNPs exhibited significantly higher antifungal efficacy against Candida albicans (p < 0.014). In conclusion, the biosynthesis of silver nanoparticles using silver fluoride and Feijoa leaf extract as an eco-friendly approach can effectively enhance the antifungal potency of toothpaste against C. albicans.