Green synthesis of silver nanoparticles using Thymbra spicata L. var. spicata (zahter) aqueous leaf extract and evaluation of their morphology-dependent antibacterial and cytotoxic activity

Abstract

Silver (Ag) nanoparticles (NPs) were green synthesized at room temperature using different concentrations of the Thymbra spicata L. var. spicata (Zahter) aqueous leaf extracts for the first time. With the synthesis of AgNPs using the leaf extract of Cynara scolymus (Artichoke) and Mentha piperita (Peppermint), the biological activities of the nanoparticles synthesized using leaf extract of three economically significant plants have been studied comparatively. Nanoparticles were characterized by different spectroscopic and microscopic analysis. TEM analysis of the biosynthesized AgNPs revealed that the size and shape of the AgNPs were changed with the plant extract concentration. Biologically synthesized AgNPs from leaf extracts of the three different plants displayed significant differences in antibacterial activity against two different gram-negative and gram-positive bacteria. Also, the results from this study show the shape dependence of the antibacterial and cytotoxic activity of silver nanoparticles synthesized using T. spicata leaf extract. The nanoparticles with different shapes exhibited the strongest antibacterial and cytotoxic activity compared to mostly spherical nanoparticles. Present results clearly indicate that biological activities of silver nanoparticles were affected by nanoparticle shape and the source of the plant extract used in the synthesis.

Antimicrobial and antibiofilm activity of green synthesized silver nanoparticles by using aqueous leaf extract of Thymus serpyllum

“…In this study, The Gram-positive bacteria showed larger zones of inhibition, compared with the Gram-negative bacteria. These findings agree with previous studies that examined antibacterial activity of AgNPs synthesized by using aqueous extract of different plant leaves [6]. This may be due to the structural difference in the cell wall composition of Gram-positive and Gram-negative bacteria.…”

“…DLS studies have revealed that the average particle size distribution of the AgNPs was 30.5 nm, and the PDI was 0.261. The size difference observed between TEM and DLS may be due to the existence of bioactive molecules of plants on the surface of AgNP or by reason of the aggregation during the sample preparation [6,26]. In addition, AgNPs dispersed in Milli-Q water showed zeta potential values of -29.5 mV for AgNPs ( Figure 5B).…”

“…The band at 3334 cm -1 shows O-H stretching vibration. The peak at 2358 and 1635 cm -1 characterizes the N-H stretching vibrations of the amides and the C═C stretching vibrations of the alkenes or the C═O stretching vibrations of the amides, respectively [6]. The functional groups estimated according to the FTIR results may have significant roles in the green synthesis of AgNPs as both reducing and stabilizing agents.…”

“…two approaches to produce NPs which are called bottom-up and top-down methods [4]. In recent years, NP synthesis has become a focus of interest by using biological methods that are nontoxic, less costly and environmentally compatible than physicochemical NP synthesis methods [4][5][6]. Synthesis of NPs under completely 'green' principles can be achieved using biologically compatible solvent systems with environmentally friendly reducing and stabilizing agents.…”

Biosynthesis of silver nanoparticles using Onosmasericeum Willd. and evaluation of their catalytic properties and antibacterial and cytotoxic activity

“…It is known that zeta potential is an important parameter related to the stability of nanoparticles. The negative value of the zeta potential indicates that AgNPs are covered with negatively-charged biomolecules and that electrostatic interaction between these nanoparticles results in the long-term stability of metal nanoparticles by preventing possible aggregation [40].…”