Biosynthesis of silver nanoparticles via Medusomyces gisevii fermentation with Tilia cordata extract: antimicrobial, antioxidant properties and phytochemical analysis

Nanotechnology is one of the most advanced fields in the twentieth century, with diverse research areas and applications [1, 2]. Multiple nanoobjects with simultaneous action capability often possess both antioxidant and antimicrobial qualities, in this case emphasizing silver nanoparticles with a size range of 1-100 nm, which exhibit high antimicrobial properties as they interact strongly with low concentrations of microorganisms. Silver ions initiate several mechanisms that disrupt natural cell processes and metabolites, such as the cell’s protein structure, the activity of the respiratory chain, cell membrane structure, and deoxyribonucleic acid (DNA) replication. Synthesis of silver nanoparticles (AgNPs) can be achieved through various methods – microwave and biological, photochemical, chemical, physical, and microemulsion. When it comes to biological synthesis, reducing agents often are microorganisms and parts of plants. The therapeutic properties of the flowers and leaves of Tilia species (Linden) contribute to their significance in pharmacogenetic research. Tilia cordata, rich in phenolic compounds, flavonoids, and tiliroside, has been traditionally used for its sedative, diuretic, and antibacterial properties, with its extracts showing potential in treating anxiety, hypertension, respiratory infections, and oxidative stress-related conditions. The goal of our study was to investigate the significance of green nanotechnology in the development of a cost-effective and eco-friendly approach for the biosynthesis of silver nanoparticles utilizing Tilia cordata extract. This process aimed to enhance the antioxidant and antimicrobial activities of the synthesized nanoparticles. To quantify the total phenolic content (mg GAE/g) in the ethanol extracts of Tilia cordata, the Folin–Ciocâlteu method was used. The highest concentration of phenolic compounds was observed in the composition of fermented T. cordata AgNPs extract. In contrast, a significantly lower phenolic content (18%) was detected in the pure T. cordata herb extract. Furthermore, the data indicate that following the synthesis of silver nanoparticles, the phenolic compound concentration decreased to 206.00±0.59 mg GAE/g ( 2%). This reduction in phenolic content is likely attributed to the role of phenolic compounds as reducing agents and stabilizers. The pure aqueous extract of T. cordata herb demonstrated antioxidant properties across all applied analytical methods, including Cupric Reducing Antioxidant Capacity (CUPRAC), Ferric Reducing Antioxidant Power (FRAP) assay, and Ultra-High Performance Liquid Chromatography (UHPLC) coupled with mass spectrometry. The surface morphology and chemical composition of AgNPs were analysed using Scanning Electron Microscopy (SEM). SEM micrographs of fermented T. cordata showed uniformly distributed nanoparticles without irregularities or holes. Transmission Electron Microscopy (TEM) images revealed diverse morphologies, predominantly spherical o