Silver nanoparticle disinfectant synthesized with aqueous extract of Minthostachys verticillata (Griseb.) Epling (Lamiaceae)

Abstract

Urgent need for faster and greener disinfectant led to the development of this formulation based on a plant extract and silver nanoparticles. The plants were selected based on their ability to reduce silver salt, antioxidant capacity, antibacterial property and ethnomedical use. Antioxidant, antimicrobial, and physicochemical prop-erties of Minthostachys verticillata “peperina” for silver nanoparticles synthesis were investigated. This species exhibits the highest antioxidant activity. Glycosylated flavonoids and tannins were identified, with rutin confirmed by UPLC-MS at 6.05 ± 0.3 mg/g of dry extract. Mv@AgNP synthesis was achieved at 85 ◦C and 10 min. UV–Vis spectroscopy confirmed a plasmon resonance peak at 440 nm, and DLS analysis indicated stable nanoparticles over 120 days. SEM revealed predominantly spherical nanoparticles (~20 ± 10 nm), while EDS confirmed the presence of the elemental silver. FT-IR analysis suggested that flavonoids and phenolic compounds acted as key reducing and stabilizing agents. Mv@AgNP demonstrated antibacterial activity against Staphylo-coccus aureus and Escherichia coli, achieving total inhibition within 5–10 min. TEM imaging revealed bacterial membrane disruption, including a blebbing effect and disintegration of the coccal membrane in S. aureus, as well as membrane lysis, the formation of holes inside the bacteria, and a bubbling phenomenon in E.coli. Biofilm assays showed significant structural damage and reduced matrix density. Additionally, Mv@AgNP exhibited antifungal activity against Candida albicans, with inhibition observed within 2 min. These findings highlight M. verticillata-derived AgNPs as a promising natural antimicrobial agent with potential applications in biomedical and pharmaceutical fields.