No abstract

Green methods have become vital for sustainable development of the scientific and commercial sphere; however, they can bring new challenges, including the need for detailed characterization and elucidation of efficacy of their products. In this study, green method of silver nanoparticles (AgNPs) production was employed using an extract from grapevine canes. The aim of the study was to contribute to the knowledge about biosynthesized AgNPs by focusing on elucidation of their antifungal efficiency based on their size and/or hypothesized synergy with bioactive substances from Vitis vinifera cane extract. The antifungal activity of AgNPs capped and stabilized with bioactive compounds was tested against the opportunistic pathogenic yeast Candida albicans. Two dispersions of nanoparticles with different morphology (characterized by SEM-in-STEM, DLS, UV-Vis, XRD, and AAS) were prepared by modification of reaction conditions suitable for economical production and their long-term stability monitored for six months was confirmed. The aims of the study included the comparison of the antifungal effect against suspension cells and biofilm of small monodisperse AgNPs with narrow size distribution and large polydisperse AgNPs. The hypothesis of synergistic interaction of biologically active molecules from V. vinifera extracts and AgNPs against both cell forms were tested. The interactions of all AgNPs dispersions with the cell surface and changes in cell morphology were imaged using SEM. All variants of AgNPs dispersions were found to be active against suspension and biofilm cells of C. albicans; nevertheless, surprisingly, larger polydisperse AgNPs were found to be more effective. Synergistic action of nanoparticles with biologically active extract compounds was proven for biofilm cells (MBIC80 20 mg/L of polydisperse AgNPs in extract), while isolated nanoparticles suspended in water were more active against suspension cells (MIC 20 mg/L of polydisperse AgNPs dispersed in water). Our results bring new insight into the economical production of AgNPs with defined characteristics, which were proven to target a specific mode of growth of significant pathogen C. albicans.

The use of microorganisms as reducing and stabilizing agents in biogenic syntheses of metal nanoparticles is an attractive approach. There is a large number of potential bioagents able to yield big amounts of various biomolecules, and to prepare nanoparticles of diverse physicochemical properties. Microscopic fungi and algae are widely studied for the preparation of nanoparticles, mainly because of their ability to produce vast amounts of extracellular proteins, enzymes, and other metabolites that can actively participate in the metal reduction and also contribute to the nanoparticle stabilization. This results in highly stable metal nanoparticles with interesting properties that can be used, for example, as antimicrobial agents (especially Ag or Cu nanoparticles) or as catalysts. This review summarizes the main, promising representatives of microscopic fungi, yeasts, and algae used for the preparation of nanoparticles of various metals.

One of the many interesting properties of silver nanoparticles is their antimicrobial activity. Since these properties are related to the morphology of the particles, it is interesting to pay attention to the antimicrobial effects of various metal nanostructures, which differ in the method of synthesis, size, or shape. One of the very interesting methods of synthesis of metal nanoparticles, which seems to be very advantageous because of its low cost, efficiency, and ecology, is the synthesis using plant extracts. For this work, woody parts of the Vitis vinifera were selected as material for the preparation of the extract. The canes of this plant are an agricultural waste containing many bioactive substances, which are not used for other significant purposes, making it a promising material for the preparation of metal nanoparticles with antimicrobial potential. The biosynthesized nanoparticles were detected and characterized using UV-Vis spectrophotometry, transmission electron microscopy (TEM) and dynamic light scattering (DLS). TEM showed that the obtained nanoparticles have a heterogeneous shape with a size 4-51 nm. The DLS analysis supported that the Z-average was 113.8 nm and 0.165 PDI value. The use of biosynthesized nanoparticles showed an excellent growth inhibition property against two strains of the opportunistic pathogenic bacteria Pseudomonas aeruginosa (ATCC 10145 and ATCC 15442). Furthermore, a bactericidal concentration (BC) 40% v/v of AgNPs was found for P. aeruginosa ATCC 15442, while no BC was found in the range of tested concentrations for P. aeruginosa ATCC 10145.