Green synthesis of silver nanoparticles using phlomis leaf extract and investigation of their antibacterial activity

Abstract

In recent years, the green synthesis of silver nanoparticles using various plant extracts has attracted great attention. This is because, these methods are simple, inexpensive and, eco-friendly. In this study, it was observed that silver ions were reduced by phlomis leaf extract after 5 min, leading to the formation of crystalline silver nanoparticles. Phlomis species is known as a rich source of flavonoids, phenylpropanoids and other phenolic compounds. The silver nanoparticles produced by the phlomis extract were characterized by different techniques including UV-vis spectrophotometry, X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and FT-IR. The SEM and TEM results indicated that AgNPs were predominantly spherical in shape with an average particle size of 25 nm. In addition, the antibacterial activity of biologically synthesized nanopartilcles against Gram-positive (Staphyloccocus aureus and Bacillus cereus) and Gram-negative (Salmonella typhimurium and Escherichia coli) bacteria was proved. This study, therefore, showed that the phlomis leaf extract could be used for the green synthesis of silver nanoparticles with the appropriate antibacterial activity.

Biologically synthesized silver nanoparticles by aqueous extract of Satureja intermedia C.A. Mey and the evaluation of total phenolic and flavonoid contents and antioxidant activity

“…[3]. Silver has long been recognized as having an inhibitory effect toward many microorganisms [4] while it is not toxic to human cells in low concentrations [5]. The most widely used and known applications of silver and silver nanoparticles are in the medical industry; for example, in topical ointments to prevent infection of burns or open wounds and also in medical devices and implants [6].…”

Biosynthesis, characterisation and therapeutic applications of plant-mediated silver nanoparticles

“…First, the demonstration of AgNPs formation is made visually by the color change from a colorless, 47 pale yellow, 66,67 yellow, 49,67 yellow-brown 46 or yellowish-brown 45,67 solution to a brown, 44,47,49 or dark brown sol 45 due to excitation of the surface plasmon resonance in the AgNPs. 46,47,66,67 The color is due to surface plasmon resonance that occurs due to the presence of collective oscillation of conducting free electrons induced by an electromagnetic field that interact, 17 and electrons gathering around the surface of the metal particles. 20 The frequency and width of the surface plasmon resonance depends on the size and shape of the metal nanoparticles, the dielectric constant of the metal and the environment.…”

“…UV-Vis spectroscopy is used to observe the change in AgNPs size, based on the wavelength of the surface plasmon resonance band. 49 Allafchian et al 66 synthesized 25-nm spherical AgNPs using a Phlomis sp. extract rich in flavonoids, phenylpropanoids and other phenolic compounds and a 0.01 M AgNO 3 solution at room temperature.…”

“…The zeta potential describes the degree of stability of a colloidal dispersion of nanoparticles. 66 The zeta potential value may be positive or negative; a negative value may occur due to the possible incorporation of bioactive components present in the extract. 45,[70][71][72] In addition, a negative potential suggests that the surface of the nanoparticles is negatively charged, which causes a strong rejection force between the particles, thus preventing their aggregation.…”

Green Biosynthesis of Spherical Silver Nanoparticles by Using Date Palm (Phoenix Dactylifera) Fruit Extract and Study of Their Antibacterial and Catalytic Activities

“…In this regard, a great deal of effort has been devoted toward the biosynthesis of silver nanoparticles using bacteria, [13][14][15][16][17] fungi, [18][19][20] actinomycetes, [21][22][23] yeast 24 and viruses [25][26][27] but the rate of nanoparticle synthesis is faster using fruits and plants extracts than microbes, and the pro-Farhadi et al : Green Biosynthesis of Spherical Silver Nanoparticles ... duced nanoparticles are more stable. 28 In recent regards, the synthesis of Ag NPs has been reported by using the natural extract of leaves, seeds and or roots of plants such as Nelumbo nucifera, 29 Anisochilus carnosus, 30 Mimusops elengi, 31 marine macroalga Chaetomorpha linum, 32 Bunium persicum, 33 Olea europaea, 34 Hamamelis virginiana, 35 Justicia adhatoda, 36 Suaeda acuminata, 37 Mentha piperita, 38 Phlomis, 39 Pennyroyal, 40 Murraya keenigii, 41 Mangifera indica, 42 Nicotiana tobaccum, 43 Bunium persicum, 44 Hamamelis virginiana. 45 However, the reaction time of Ag + ions for complete reduction in these works was very long.…”