Calligonum comosum and Fusarium sp. extracts as bio-mediator in silver nanoparticles formation: characterization, antioxidant and antibacterial capability

C. S, Anil VS, Raghavan S. Phytosynthesis of silver nanoparticles using aqueous sandalwood (Santalum album L.) leaf extract: Divergent effects of SW-AgNPs on proliferating plant and cancer cells

The biogenic approach for the synthesis of metal nanoparticles provides an efficient eco-friendly alternative to chemical synthesis. This study presents a novel route for the biosynthesis of silver nanoparticles using aqueous sandalwood (SW) leaf extract as a source of reducing and capping agents under mild, room temperature synthesis conditions. The bioreduction of Ag+ to Ago nanoparticles (SW-AgNPs) was accompanied by the appearance of brown color, with surface plasmon resonance peak at 340-360 nm. SEM, TEM and AFM imaging confirm SW-AgNP's spherical shape with size range of 10-32 nm. DLS indicates a hydrodynamic size of 49.53 nm with predominant negative Zeta potential, which can contribute to the stability of the nanoparticles. FTIR analysis indicates involvement of sandalwood leaf derived polyphenols, proteins and lipids in the reduction and capping of SW-AgNPs. XRD determines the face-centered-cubic crystalline structure of SW-AgNPs, which is a key factor affecting biological functions of nanoparticles. This study is novel in using cell culture methodologies to evaluate effects of SW-AgNPs on proliferating cells originating from plants and human cancer. Exposure of groundnut calli cells to SW-AgNPs, resulted in enhanced proliferation leading to over 70% higher calli biomass over control, enhanced defense enzyme activities, and secretion of metabolites implicated in biotic stress resistance (Crotonyl isothiocyanate, Butyrolactone, 2-Hydroxy-gamma-butyrolactone, Maltol) and plant cell proliferation (dl-Threitol). MTT and NRU were performed to determine the cytotoxicity of nanoparticles on human cervical cancer cells. SW-AgNPs specifically inhibited cervical cell lines SiHa (IC50-2.65 ppm) and CaSki (IC50-9.49 ppm), indicating potential use in cancer treatment. The opposing effect of SW-AgNPs on cell proliferation of plant calli (enhanced cell proliferation) and human cancer cell lines (inhibition) are both beneficial and point to potential safe application of SW-AgNPs in plant cell culture, agriculture and in cancer treatment.

Synthesis and Antioxidant Activity of Silver Nanoparticles Using the Odontonema strictum Leaf Extract

The aqueous extract of the leaves of Odontonema strictum (OSM) is used in folk medicine for its antihypertensive properties, and it contains a wide range of secondary metabolites, mostly polyphenols such as verbascoside and isoverbascoside, which could play a major role in the preparation of silver nanoparticles. In this study, we aimed to prepare AgNPs for the first time using the OSM leaf extract (OSM-AgNPs) to investigate their free radical-scavenging potency against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide (H₂O₂). Dynamic light scattering (DLS), UV/Vis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) were used to characterize the OSM-AgNPs. With a size around 100 nm and a ζ-potential of −41.1 mV, OSM-AgNPs showed a good stability and a better colloidal property due to electrostatic repulsion and the dispersity. The strong absorption peak at 3 keV in the EDX spectra indicated that silver was the major constituent. Additionally, the existence of silver atoms was confirmed by the Ag 3d_5/2 peak around 367 eV in the XPS spectra. IC₅₀ values of 116 μg/mL and 4.4 μg/mL were obtained for the scavenging activities of DPPH and H₂O₂, respectively. The synthetic OSM-AgNPs can be further exploited as potential antioxidant agents.

Myco-Facilitated Biosynthesis of Nano-Silver From Wasp Nest Fungus, Paecilomyces variotii, and Its Antimicrobial Activity Against MTCC Strains

The utility of fungi as stabilizing and reducing agents in the biogenic synthesis of silver nanoparticles is striking due to the production of large quantities of biomolecules of minute toxic residuals. During the current study, sunlight- and dark-assessed silver nanoparticles were synthesized from wasp nest fungus, Paecilomyces variotii, at different pHs. Synthesized silver nanoparticles (AgNPs) at 6 pH were found to be more prominent than at 7 and 8 pHs. AgNPs were within the 20- to 90-nm range and were polygonal and elongated in shape. FTIR spectra of light-mediated AgNPs showed diverse transmittance bands than the silver nanoparticles synthesized in the dark. The synthesized AgNPs were found with diverse antimicrobial activities against pathogenic MTCC bacterial strains, i.e., Staphylococcus aureus, Vibrio parahaemolyticus, Escherichia coli, Shewanella putrefaciens, and fungus, Candida albicans. Aqueous filtrate and filtrate-mediated AgNPs combined with methanol solvent extract of yeast extract manitol broth (YEMB) had more inhibitory effects on all bacteria and Candida albicans. Furthermore, the combined effect of AgNPs and methanol solvent extract from YEMB culture filtrate was found more effective against E. coli, while AgNPs combined with methanol solvent of aqueous filtrate had inhibitory effects on E. coli and Candida albicans.

Bacterial Mediated Rapid and Facile Synthesis of Silver Nanoparticles and Their Antimicrobial Efficacy against Pathogenic Microorganisms

In the present study, silver nanoparticles (AgNPs), biosynthesized using culture supernatant of bacterial strain Paenarthrobacter nicotinovorans MAHUQ-43, were characterized and their antimicrobial activity was investigated against both Gram-positive Bacillus cereus and Gram-negative bacteria Pseudomonas aeruginosa. Bacterial-mediated synthesized AgNPs were characterized by UV-Visible (UV-Vis) spectrophotometer, field emission-transmission electron microscopy (FE-TEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) analysis. The UV-Vis spectral analysis showed the absorption maxima at 466 nm which assured the synthesis of AgNPs. The FE-TEM analysis revealed the spherical shape of nanoparticles with the size range from 13 to 27 nm. The EDX and XRD analysis ensured the crystalline nature of biosynthesized AgNPs. The FTIR analysis revealed the involvement of different biomolecules for the synthesis of AgNPs as reducing and capping agents. The bacterial-mediated synthesized AgNPs inhibited the growth of pathogenic strains B. cereus and P. aeruginosa and developed a clear zone of inhibition (ZOI). The MIC and MBC for both pathogens were 12.5 µg/mL and 25 µg/mL, respectively. Moreover, field emission scanning electron microscopy analysis revealed that the synthesized AgNPs can destroy the outer membrane and alter the cell morphology of treated pathogens, leading to the death of cells. This study concludes the eco-friendly, facile and rapid synthesis of AgNPs using P. nicotinovorans MAHUQ-43 and synthesized AgNPs showed excellent antimicrobial activity against both Gram-positive and Gram-negative pathogens.

Biosynthesis of silver nanoparticles using Malva parviflora and their antifungal activity

Cheeseweed mallow (Malva parviflora L.) was used to biosynthesize silver nanoparticles. The biosynthesized silver nanoparticles were classified by UV-vis Spectroscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). The shape and size distribution were visualized by Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), and Zeta potential analysis. The chemical composition of M. parviflora leaf extract was identified by Gas Chromatography and Mass Spectroscopy (GC/MS). Finally, in vitro antifungal assay was done to assess the potential of biosynthesized silver nanoparticles and crude leaf extract of M. parviflora for inhibiting the mycelial growth of phytopathogenic fungi. The UV-vis analysis manifests the formation of silver nanoparticles. FTIR analysis established that chemicals of the leaf extract stabilized the biosynthesized silver nanoparticles by binding with the free silver ions. The TEM, FE-SEM and zeta potential analyzer confirmed that the biosynthesized silver nanoparticles were mostly spherical with an average diameter of 50.6 nm. The biosynthesized silver nanoparticles and leaf extract of M. parviflora effectively mitigate the mycelial growth of Helminthosporium rostratum, Fusarium solani, Fusarium oxysporum, and Alternaria alternata. The maximum reduction in mycelial growth by biosynthesized nanoparticles was observed against H. rostratum (88.6%). Whereas, the leaf extract of M. parviflora was most effective against F. solani (65.3%). Thus, the biosynthesis of nanoparticle assisted by M. parviflora is a feasible and eco-friendly method for the synthesis of silver nanoparticles. Further the silver nanoparticles and leaf extract of M. parviflora could be explored for the development of the fungicide.

Fusarium as a Novel Fungus for the Synthesis of Nanoparticles: Mechanism and Applications

Nanotechnology is a new and developing branch that has revolutionized the world by its applications in various fields including medicine and agriculture. In nanotechnology, nanoparticles play an important role in diagnostics, drug delivery, and therapy. The synthesis of nanoparticles by fungi is a novel, cost-effective and eco-friendly approach. Among fungi, Fusarium spp. play an important role in the synthesis of nanoparticles and can be considered as a nanofactory for the fabrication of nanoparticles. The synthesis of silver nanoparticles (AgNPs) from Fusarium, its mechanism and applications are discussed in this review. The synthesis of nanoparticles from Fusarium is the biogenic and green approach. Fusaria are found to be a versatile biological system with the ability to synthesize nanoparticles extracellularly. Different species of Fusaria have the potential to synthesise nanoparticles. Among these, F. oxysporum has demonstrated a high potential for the synthesis of AgNPs. It is hypothesised that NADH-dependent nitrate reductase enzyme secreted by F. oxysporum is responsible for the reduction of aqueous silver ions into AgNPs. The toxicity of nanoparticles depends upon the shape, size, surface charge, and the concentration used. The nanoparticles synthesised by different species of Fusaria can be used in medicine and agriculture.

Biosynthesis of Silver Nanoparticles Using Culture Supernatant of Shewanella sp. ARY1 and Their Antibacterial Activity

PURPOSE

In this study, silver nanoparticles (AgNPs) were biosynthesized using culture supernatant of strain Shewanella sp. ARY1, characterized and their antibacterial activity was investigated against Gram-negative bacteria Escherichia coli and Klebsiella pneumoniae.

METHODS

The strain Shewanella sp. ARY1 was isolated from river Yamuna, Delhi and used for biosynthesis of AgNPs via extracellular approach. Biosynthesized AgNPs were characterized by UV-Visible (UV-Vis) spectrophotometer, fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Antibacterial activity of AgNPs was determined by well diffusion, broth microdilution and streaking plate assay to determine the zone of inhibition (ZOI), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), respectively. The effect of AgNPs on treated bacteria was investigated by electron microscopy analysis. Further, the biocompatibility of AgNPs was tested against mice erythrocytes (RBC) by hemolytic assay.

RESULTS

The UV-Vis spectral analysis revealed absorption maxima at 450 nm which confirmed the formation of AgNPs. The FTIR analysis suggested the involvement of various supernatant biomolecules, as reducing and capping agents in the synthesis of AgNPs. The XRD and EDX analysis confirmed the crystalline and metallic nature of AgNPs, respectively. The TEM and SEM analysis showed nanoparticles were spherical with an average size of 38 nm. The biosynthesized AgNPs inhibited the growth and formed a clear zone of inhibition (ZOI) against tested Gram-negative strains. The MIC and MBC were determined as 8-16 µg/mL and 32 µg/mL, respectively. Further, electron microscopy analysis of treated cells showed that AgNPs can damage the outer membrane, release of cytoplasmic contents, and alter the normal morphology of Gram-negative bacteria, leading to cell death. The hemolytic assay indicated that the biosynthesized AgNPs were biocompatible at low dose concentrations.

CONCLUSION

This study demonstrates an eco-friendly process for extracellular synthesis of AgNPs using Shewanella sp. ARY1 and these AgNPs exhibited excellent antibacterial activity, which may be used to combat Gram-negative pathogens.

Biosynthesis of Silver Nanoparticles Using Cucumis prophetarum Aqueous Leaf Extract and Their Antibacterial and Antiproliferative Activity Against Cancer Cell Lines

Biosynthesized nanoparticles are gaining attention because of biologically active plant secondary metabolites that help in green synthesis and also due to their unique biological applications. This study reports a facile, ecofriendly, reliable, and cost-effective synthesis of silver nanoparticles using the aqueous leaf extract of Cucumis prophetarum (C. prophetarum) and their antibacterial and antiproliferative activity. Silver nanoparticles were biosynthesized using the aqueous leaf extract of C. prophetarum, which acted as a reducing and capping agent. The biosynthesized C. prophetarum silver nanoparticles (Cp-AgNPs) were characterized using different techniques, such as UV-visible spectroscopy, dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX). Phytochemical analysis was performed to determine the phytochemicals responsible for the reduction and capping of the biosynthesized Cp-AgNPs. The antioxidant activity of the biosynthesized nanoparticles was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. Their antibacterial activity was checked against Staphylococcus aureus (Gram-positive) and Salmonella typhi (Gram-negative) bacteria. The biosynthesized nanoparticles showed dosage-dependent inhibition activity with a significant zone of inhibition and were more effective toward S. typhi as compared to S. aureus. Their antiproliferative activity was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on selected cancer cell lines. The IC₅₀ values of Cp-AgNPs on A549, MDA-MB-231, HepG2, and MCF-7 were found to be 105.8, 81.1, 94.2, and 65.6 μg/mL, respectively, and this showed that the Cp-AgNPs were more potent toward MCF-7 as compared to other cell lines used in this study. This work revealed that the biosynthesized silver nanoparticles using C. prophetarum leaf extract were associated with good antibacterial activity and antiproliferative potential against selected cancer cell lines. The biosynthesized C. prophetarum AgNPs can be further exploited as a potential candidate for antioxidant, antibacterial, and anticancer agents.

Biogenic synthesis of silver nanoparticles: Antibacterial and cytotoxic potential

In green chemistry, the application of a biogenic material as a mediator in nanoparticles formation is an innovative nanotechnology. Our current investigation aimed at testing the cytotoxic potential and antimicrobial ability of silver nanoparticles (AgNPs) that were prepared using Calligonum comosum roots and Azadirachta indica leaf extracts as stabilizing and reducing agents. An agar well diffusion technique was employed to detect synthesized AgNPs antibacterial ability on Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus bacterial strains. Furthermore, their cytotoxic capability against LoVo, MDA-MB231 and HepG2 ca cells was investigated. For phyto-chemical detection in the biogenic AgNPs the Fourier-transform infrared spectroscopy (FT-IR) was considered. Zeta sizer, TEM (Transmission Electron Microscope) and FE-SEM (Field Emission Scanning Electron Microscope) were used to detect biogenic AgNPs' size and morphology. The current results showed the capability of tested plant extract for conversion of Ag ions to AgNPs with a mean size ranging between 90.8 ± 0.8 and 183.2 ± 0.7 nm in diameter. Furthermore, prepared AgNPs exhibited apoptotic potential against HepG2, LoVo, and MDA-MB 231cell with IC₅₀ ranging between 10.9 and 21.4 μg/ml and antibacterial ability in the range of 16.0 ± 0.1 to 22.0 ± 1.8 mm diameter. Activation of caspases in AgNPs treated cells could be the main indicator for their positive effect causing apoptosis. The current investigation suggested that the green production of AgNPs could be a suitable substitute to large-scale production of AgNPs, since stable and active nanoparticles could be obtained.

Antibacterial and Cytotoxic Potential of Biosynthesized Silver Nanoparticles by Some Plant Extracts

The provision of nanoparticles using biogenic material as a part of green chemistry is an attractive nanotechnology. The current research aimed to test the antimicrobial and cytotoxic efficacy of silver nanoparticles synthesized by extracts of Phoenix dactylifera, Ferula asafetida, and Acacia nilotica as reductant and stabilizing agents in silver nanoparticle formation. Synthesized nanoparticles were evaluated for their antimicrobial activity against Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa and Escherichia coli (Gram-negative) using an agar well diffusion assay. Furthermore, cytotoxic ability was investigated against LoVo cells. The potential phyto-constituents of plant extracts were identified by Fourier-transform infrared spectroscopy (FT-IR) techniques. Field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), and zeta potential analyzed the size and morphology of the biogenic nanoparticles. The current study revealed the ability of the tested plant extract to convert silver ions to silver nanoparticles with an average size that ranged between 67.8 ± 0.3 and 155.7 ± 1.5 nm in diameter. Biogenic AgNPs showed significant antibacterial ability (10 to 32 mm diameter) and anticancer ability against a LoVo cell with IC50 ranged between 35.15–56.73 μg/mL. The innovation of the present study is that the green synthesis of NPs, which is simple and cost effective, provides stable nano-materials and can be an alternative for the large-scale synthesis of silver nanoparticles.