Abstract
Natural extracts are a rich source of biomolecules that are useful not only as antioxidant drugs or diet supplements but also as complex reagents for the biogenic synthesis of metallic nanoparticles. The natural product components can act as strong reducing and capping substrates guaranteeing the stability of formed NPs. The current work demonstrates the suitability of extracts of Camellia sinensis, Ilex paraguariensis, Salvia officinalis, Tilia cordata, Levisticum officinale, Aegopodium podagraria, Urtica dioica, Capsicum baccatum, Viscum album, and marine algae Porphyra Yezoensis for green synthesis of AgNPs. The antioxidant power of methanolic extracts was estimated at the beginning according to their free radical scavenging activity by the DPPH method and reducing power activity by CUPRAC and SNPAC (silver nanoparticle antioxidant capacity) assays. The results obtained by the CUPRAC and SNAPC methods exhibited excellent agreement (R2~0.9). The synthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), dynamic light scattering (DLS) particle size, and zeta potential. The UV-vis absorption spectra showed a peak at 423 nm confirming the presence of AgNPs. The shapes of extract-mediated AgNPs were mainly spherical, spheroid, rod-shaped, agglomerated crystalline structures. The NPs exhibited a high negative zeta potential value in the range from −49.8 mV to −56.1 mV, proving the existence of electrostatic stabilization. FTIR measurements indicated peaks corresponding to different functional groups such as carboxylic acids, alcohol, phenol, esters, ethers, aldehydes, alkanes, and proteins, which were involved in the synthesis and stabilization of AgNPs. Among the examined extracts, green tea showed the highest activity in all antioxidant tests and enabled the synthesis of the smallest nanoparticles, namely 62.51, 61.19, and 53.55 nm, depending on storage times of 30 min, 24 h, and 72 h, respectively. In turn, the Capsicum baccatum extract was distinguished by the lowest zeta potential, decreasing with storage time from −66.0 up to −88.6 mM.
Highlights
Nanoparticles (NPs) are of great interest in engineering, chemical, and biomedical sciences
Extracts prepared from natural raw materials, have a complex composition, which is the source of many phytochemicals, acting as reducing agents and as stabilizing factors that ensure the appropriate monodispersity of nanoparticles
The current research proves that methanol extracts obtained from ten natural products, representatives of common herbs (Salvia officinalis, Tilia cordata, Levisticum officinale, Aegopodium podagraria, Urtica dioica, Viscum album), vegetables (Capsicum baccatum), marine algae (Porphyra Yezoensis), and teas (Camellia sinensis, Ilex paraguariensis), can be useful for the synthesis of AgNPs
Summary
Nanoparticles (NPs) are of great interest in engineering, chemical, and biomedical sciences. These small particles, due to their high surface-to-volume ratio, have different properties compared to chemical species of the same composition. Nanoparticles belong to highly advanced and specialized biomedical products [1]. There are several interesting applications of nanoparticles in medicine and pharmacy: for example, in medical imaging, as nanocomposites, filters, components of drug delivery systems, and formulations for the treatment of cancer [2,3,4,5]. Gold nanoparticles have found applications in analytical procedures for the detection of cancer cells, proteins, and antibodies. Silver nanoparticles are known as antimicrobial agents even against infectious organisms such as Escherichia coli, Bacillus subtilis, Vibria cholera, Pseudomonas aeruginosa, Syphillis typhus, and Staphylococcus aureus. Apart from gold and silver nanoparticles, the literature describes nanoparticles of zinc oxide (ZnONPs), selenium (SeNPs), copper oxide (CuONPs), copper (CuNPs), nickel oxide (NiONP), and iron (INPs), covering iron oxide (ION) nanoparticles, iron hydroxide (IOOH), and zero-valent iron (ZVI) nanoparticles [6,7,8,9,10,11]
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