Green Synthesis and Antibacterial Properties of Silver Nanoparticles of Lawsonia inermis, Rhamnus frangula, Camellia sinensis and Thymus vulgaris Extracts

Green synthesis of silver nanoparticles using Malachra alceifolia (wild okra) for wastewater treatment and biomedical applications with molecular docking approach

The current investigation focused on the green synthesis of silver nanoparticles (Ag NPs) using Malachra alceifolia (Ma) (the common name is wild okra) leaf extract. The morphological, structural, and optical properties of the synthesized Ma-Ag NPs were characterized by various techniques. The absorption spectral studies (UV-vis and FTIR) confirm the formation of Ma-Ag NPs and their band gap was calculated as 2.1 eV with the help of Tauc's equation. The XRD study gives information about the crystalline nature and FCC structure. The SEM analysis estimates the particle size as 10-55 nm and the average size as 28 nm with a spherical shape. Furthermore, biological studies such as antibacterial activity was performed by the broth dilution method whereas antioxidant was studied through the DPPH radical scavenging technique. To compare the antibacterial activity between Gram-positive and Gram-negative pathogens, the highest bacterial growth of inhibition was observed for Pseudomonas aeruginosa than Staphylococcus aureus when increasing the concentration of the plant extract and Ma-Ag NPs. The scavenging activity of DPPH for both leaf extract and synthesized Ma-Ag NPs was represented in a dose-dependent manner (0.1-1.0 mg/mL), Ma-Ag NPs have shown a significant scavenging activity ranging from 39 to 54% with an average IC50 value of 0.87 ± 0.08. Furthermore, a molecular docking study was performed to confirm the binding interaction outline between the bioactive molecule methyl commate A, Ma-Ag NPs, and proteins such as Aminotransferase and Tyrosyl-tRNA synthetase active sites. The highest interaction tendency was observed between the Aminotransferase and methyl commate A with a binding energy of - 7.79 kcal/mol-1. The high electronegative oxygen of the ligand interacts with H-N- of Lys98 (-O--H-N-) through the formation of hydrogen bond by 3.53A° distance. In addition, the photocatalytic efficiency of Ma-Ag NPs was studied with methylene blue dye degradation under sunlight irradiation at different time intervals. The attained photocatalytic degradation efficiency was 98.3% after 120 min.

Green synthesis and characterization of silver nanoparticles using Morinda lucida leaf extract and evaluation of its antioxidant and antimicrobial activity

This study emphasizes the production of eco-friendly silver nanoparticles from a medicinal plant extract of Morinda lucida (M. lucida) and investigated its antioxidant and antimicrobial activity. Phytochemical screening of M. lucida (ML) leave extract was carried out and observed to contain some fundamental phyto-reducing agents such as reducing sugar, proteins, and alkaloids. The green synthesized AgNPs (ML-AgNPs) were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission emission microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy dispersive X-ray analysis (EDX). Thermo gravimetric analysis (TGA) was performed on the synthesized ML-capped AgNPs to determine the thermal stability and the formation of the green synthesized AgNPs. The formation of AgNPs was confirmed by the UV-vis absorption spectra, which showed an absorption band at 420 nm. The morphology of ML extract-mediated AgNPs was mostly spherical and rough-edged crystallite nanostructures, with an average particle size of 11 nm. The FTIR analyses revealed distinctive functional groups which were directly involved in the synthesis and stability of AgNPs. The crystallite size was 8.79 nm, with four intense peaks at 2θ angles of 38°, 44°, 64°, and 77°. At an energy level of 3.4 keV, a significant signal was observed indicating the production of thermally stable and pure crystallite AgNPs. The antioxidant property of green synthesized ML-AgNPs was determined to be 40% higher than that of crude M. lucida leaf extract. The ability of green synthesized ML-AgNPs to scavenge free radicals also increased in the order of OH- < NO < H2O2. The ML-AgNPs have strong activities with a maximum against P. vulgaris and a minimum with E. faecalis.

Green synthesis of (CS/OLE) AgNPs and evaluation of their physico-chemical characteristic

The present article involves the bio-synthesis of (Chitosan/olive leaf extract) silver nanoparticles (CS/OLE) AgNPs using a simple green electrochemical procedure followed by UV-irradiation time. The properties and structure of the resulting (CS/OLE) AgNPs were characterized by employing several analytical techniques including, Infrared spectrum (FT-IR), UV–VIS spectroscopy, X-ray analysis (XRD), energy-dispersive X-ray (EDX) and degredation. Besides, the studying of the thermal characteristics of the (CS/OLE) AgNPs electrets were also investigated. Formation of Ag nanoparticles was observed upon varying the solution color from faint yellow into yellowish brown and was achieved by the appearance of absorption peak at about ~ 410 nm of the resulting AgNPs corresponding to the surface plasmon resonance (SPR). The sharp peaks appear at 32.16°, 46.19°, 54.75°, 57.59°, and 76.7°, indicating the presence of AgNPs as shown from XRD. With comparing the anti-bacterial efficiency of (CS/OLE) AgNPs and (CS/OLE) we found that the AgNPs display a relatively high anti-bacterial activity than in plant extract and chitosan alone. The electrical properties of (CS/OLE) AgNPs films were studied by global thermally stimulated depolarization current (TSDC) spectra for explaining the relaxation phenomena of the samples. In addition, the molecular parameters (The activation energy Ea and pre-exponential time τo), have been evaluated by the Arrhenius equation. The Ea was found in ~ (0.39–0.62 eV) for (CS/OLE).