Fabrication and characterization of AgMgO nanocomposites synthesized using Parmelia tiliaceae : Evaluation of their antibacterial, photocatalytic, antialgal, and cytotoxic activities

The increasing demand for eco-friendly and multifunctional nanomaterials has intensified interest in green synthesis strategies for biomedical and environmental applications. In this study, AgMgO nanocomposites (NCs) were successfully synthesized using Parmelia tiliaceae extract as a biological reducing and stabilizing agent. The synthesized NCs were comprehensively characterized by UV–Vis spectroscopy, SEM, STEM, DLS, FTIR, EDX, XRD, and TGA analyses, confirming their spherical morphology, homogeneous distribution, and particle size in the range of 20–80 nm. The biological and functional properties of the AgMgO NCs were systematically evaluated. The nanocomposites exhibited notable antibacterial activity, with a maximum inhibition zone of 17.3 ± 0.5 mm against Escherichia coli O157:H7 ATCC 35150, and a strong antibiofilm effect, achieving up to 94% inhibition against Staphylococcus aureus ATCC 29213. In addition, effective antialgal activity was observed across all tested concentrations. The photocatalytic performance of the NCs demonstrated moderate efficiency, achieving 61.8% degradation of methylene blue (2 mg/L) within 180 min, indicating their potential as a proof-of-function system for environmental remediation. Furthermore, the synthesized NCs showed significant cytotoxic activity against A549 lung cancer cells. Overall, the results demonstrate that lichen-mediated AgMgO NCs are cost-effective, biocompatible, and multifunctional materials with promising applications in antimicrobial, environmental, and biomedical fields.