Green synthesis of silver nanoparticles using calamondin (Citrus microcarpa) peel essential oil and evaluation of their biological activities

The exceptional biological qualities of silver nanoparticles (AgNPs), including their antibacterial, antioxidant, and anti-inflammatory capabilities, have garnered a lot of interest. The synthesis of AgNPs using plant-derived compounds is considered an environmentally friendly method, limiting the use of toxic chemicals. Among them, natural essential oils, rich in flavonoids and terpenoids, have shown effective roles as reducing agents and stabilizers. Calamondin (Citrus microcarpa) peel essential oil (CmEO), which is notable for its high limonene and flavonoid content, was chosen as the green synthesis agent in this study. AgNPs were created by reducing AgNO3 with CmEO, and they were examined using UV-Vis, FTIR, DLS, and SEM. Dynamic light scattering (DLS) and SEM based on the analysis, it was observed that the AgNPs-CmEO possessed a spherical morphology with an average particle size of approximately 204.3 nm. The UV–Vis spectrum exhibited a characteristic surface plasmon resonance peak around 420 nm. In addition, both Gram-positive and Gram-negative bacteria were susceptible to the antibacterial activity of AgNPs-CmEO. However, the activity was still lower than that of gentamicin. The antioxidant activity was moderate, with IC50 of 617.37 μg/mL (DPPH) and 385.48 μg/mL (ABTS). Overall, CmEO is a potential bioreducing agent for AgNPs synthesis, opening up potential applications in food preservation and biomedicine while indicating the need for further process optimization to improve product performance and stability.