Green Synthesis of Silver Nanoparticles Using <i>Myrtillocactus geometrizans</i> Extract for Enhancing Stability and Antimicrobial Properties

ABSTRACT The green synthesis of silver nanoparticles (AgNPs) has attracted considerable interest due to their antimicrobial properties and because this method is more sustainable than conventional techniques. In this context, the Garambullo cactus ( Myrtillocactus geometrizans ) is emerging as a valuable source of bioactive compounds for their production. The whole fruit showed 83.5% moisture, with 6.9% fat, 5.8% protein, 5.3% ash, 75.2% carbohydrates, 6.8% fiber (dry basis), and 45.56 mg GAE/100 g phenolics, highlighting reducing‐stabilizing potential. The formation of AgNPs was evidenced by a color change, as well as the appearance of an absorption peak in the 420–430 nm range in the UV–vis spectrum. High‐resolution scanning electron microscopy (HR‐SEM) images revealed spherical particles with sizes ranging from 11 to 45.6 nm, and x‐ray diffraction (XRD) analysis confirmed their crystalline structure. Dynamic light scattering (DLS) indicated good colloidal stability with a zeta potential greater than −30 mV. FTIR revealed phenolic and carbonyl groups aiding nanoparticle formation. Finally, AgNPs exhibited remarkable antimicrobial activity against Escherichia coli ATCC 11229 and Staphylococcus aureus ATCC 6538, with inhibition halos comparable to those of conventional antibiotics at a concentration of 1 × 10⁴. Garambullo extracts allow the synthesis and stabilization of AgNPs with potential applications.