Fabrication Of AuNPs Research Articles

Supported gold nanoparticles on lignosulfonate coated magnetic nanoparticles: Investigation of its catalytic efficiency in the reductive formylation of nitroarenes

This article describes a biogenic synthesis towards the fabrication of Au NPs over sodium lignosulfonate (NaLS) modified Fe3O4 bio-nanocomposite and its catalytic and biological applications. The morphology and physicochemical characteristics of the material were determined over a number of analytical techniques like FT-IR, FE-SEM, TEM, EDS, XRD, ICP-OES and VSM. The prepared Fe3O4@NaLS/Au nanocomposite presented an excellent catalytic performance in the one-pot synthesis of N-formyl amines via reductive formylation of different nitrobenzene derivatives using NaBH4 as the hydride source and triethyl orthoformate [CH(OEt)3] as the formylating agent. Due to magnetic core, the nanocatalyst was retrieved magnetically with facile and recycled for 8 successive runs keeping its potential intact.

In vitro assessment of antimicrobial, anti-inflammatory, and schistolarvicidal activity of macroalgae-based gold nanoparticles

There is a growing need to improve facile, eco-friendly, and cheap approaches for nanoparticle (NP) synthesis. Green protocols have been investigated for the fabrication of NPs using several natural sources as plants, algae, fungi, and bacteria. Thus, the present study proposed a rapid, convenient, and efficient biosynthesis of gold NPs (Au-NPs) using the ethanolic extracts of three macroalgae, i.e., Cystoseira myrica, C. trinodis, and Caulerpa prolifera. The reduction of Au ions and the fabrication of Au-NPs were validated using ultraviolet-visible (UV–Vis) spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and zeta potential analysis. The produced Au-NPs were tested for their antibacterial, antifungal, anti-inflammatory, and schistolarvicidal activity. Results revealed the formation of Au-NPs with an average size of 12.6–15.5 nm and different shapes that are mainly spherical with pure crystalline nature. The strong antibacterial activities of C. trinodis– and C. myrica–based Au-NPs against E. coli (inhibition zones of 22 and 19 mm) and against Staphylococcus aureus (inhibition zones of 18 and 20.5 and mm) were recorded, respectively. On the other hand, the high antifungal activity of C. trinodis Au-NPs against Aspergillus niger and Alternaria alternate showed the inhibition zones of 18 and 17 mm, respectively. The high antifungal activity of C. trinodis Au-NPs against Candida albicans (inhibition zone 16 mm) was also recorded. Regarding anti-inflammatory and schistolarvicidal activity, Au-NPs fabricated using C. myrica showed 64.2% of the inhibitory effect on protein denaturation and recorded the highest schistolarvicidal activity against Schistosoma mansoni cercariae that sank and died after 7 min. Overall, these findings proved that macroalgal ethanolic extracts can be effectively used for the biosynthesis of Au-NPs. These Au-NPs offer a significant alternative antimicrobial, anti-inflammatory, and schistolarvicidal agents. for biomedical uses.

Fabrication of resveratrol coated gold nanoparticles and investigation of their effect on diabetic retinopathy in streptozotocin induced diabetic rats

This study includes the fabrication of gold nanoparticles (AuNPs) with the help of a plant polyphenol called Resveratrol through an ecofriendly synthetic process without any use of harmful reductants. In the fabrication of AuNPs, Resveratrol acts as both stabilizing and reducing agent. The prepared AuNPs is tested on streptozotocin (STZ) induced diabetic rats for their amelioration consequence. The images of TEM displayed the development of spherical nanoparticles (NPs) with a median of 20 nm particle size. The STZ injected diabetic rats were administrated orally with calcium dobesilate (CD; 500 mg/kg/day) or AuNPs (200, 300 mg/kg/day) for a period of 3 months. The characteristics displayed by AuNPs were found to be similar with CD in decreasing permeability of blood–retinal barrier in STZ injected diabetic rats. The retinal vessels in the AuNPs administrated diabetic rats were observed to be decreased through the retinal histopathological examination. In the AuNPs administrated diabetic rats, the retinal expression of renal Pigment Epithelium-Derived Factor (PEDF) was observed to be increased and the Vascular Endothelial Growth Factor (VEGF-1), which was increased in diabetic rats was declined on treating with AuNPs. On treating the STZ injected diabetic rats with AuNPs, all the retinal mRNA expressions of VEGF-1, Tumor Necrosis Factor (TNFα), Monocyte Chemotactic Proteins-1 (MCP-1), Intercellular Adhesion Molecule-1 (ICAM-1), and Interleukin (IL)-6, IL-1β were observed to be reduced. Furthermore, AuNPs can reduce phosphorylation of Nuclear Factor Kappa B (NF-κB) p65 and Extracellular signal Regulated Kinase (ERK) 1/2 along with a growth in nuclear translocation of pNF-κB p65 produced by STZ. To conclude, the protective effect of AuNPs on STZ injected diabetic rats could help in redeveloping the balance among the inhibitors and stimulators of angiogenesis. Furthermore, on treating with AuNPs results in inhibiting the signaling pathway of ERK1/2 as well as with amelioration of retinal inflammation through trans repression of NF-κB.

Rapid mediated biosynthesis and quantification of AuNPs using persimmon (Diospyros Kaki L.f) fruit extract

Persimmon (Diospyros Kaki L.f), as a common fruit, is rich in polyphenols, flavonoids and sugars, having high ability for synthesis of nanoparticles. Thus, biosynthesis of AuNPs using persimmon fruit extract was investigated in this study. The results of UV–visible spectra, transmission electron microscopy images and dynamic light scattering demonstrated that the size and shape of AuNPs highly depended on the concentration of HAuCl4·4H2O and reaction temperature. When 1.0 and 1.5 mM of HAuCl4·4H2O were used as precursors, triangular and hexagonal AuNPs were formed; furthermore, 2.0 mM of HAuCl4·4H2O induced the formation of nanoaggregates. Although higher temperatures (e.g., 50, 60 and 70 °C) boosted the isotropic growth of AuNPs, they had no expressive impact on AuNPs size. Centrifugal ultrafiltration method with inductively coupled plasma-mass spectrometry was applied to assess the transformation efficiency of Au3+ during this biosynthesis procedure. So, the results indicated that more than 97% of Au3+ ions were successfully converted into AuNPs. In addition, the XRD analysis confirmed that AuNPs had face-centered cubic structure. Fourier transform infrared spectroscopy revealed that different functional groups (especially hydroxyl group) were mainly involved in the fabrication of AuNPs. The biosynthesized AuNPs exhibited good antioxidant and catalytic activities.

Homogeneous Plasmonic Au Nanoparticles Fabrication Using In Situ Substrate Heating by Sputtering

Increased usage of gold nanoparticles (Au NPs) in the high-tech world made these one of the pivotal components for large number of applications. In the present work, we present the fabrication of Au NPs and their characterisation for shape, size distribution and surface plasmon (SP) studies. Au NPs were synthesised on Si substrate in a self-assembled manner with different densities. In situ substrate heating was done to fabricate Au NPs with minimum size variation and direct deposition of these on the Si substrate. The prepared samples were then characterised by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), high-resolution transmission electron microscope (HRTEM), photoluminescence (PL) and UV-Vis diffuse reflectance spectroscopy (UV-DRS). The average size of the nanoparticles from FESEM was found to be 3, 5 and 9 nm for substrate temperatures of 400, 500 and 600 °C, respectively. Due to the high density of deposited Au NPs on the substrate, a strong and broad surface plasmon band was observed. UV spectra showed a shift in the absorption maxima towards the red region with increase in the temperature of substrate.

Gum-Mediated Fabrication of Eco-Friendly Gold Nanoparticles Promoting Cell Division and Pollen Germination in Plant Cells

In this study we reported a simple approach for the green synthesis of gold nanoparticles (AuNPs) using the Terminalia arjuna gum extract as a source of reducing and stabilizing compounds. The fabrication of AuNPs was confirmed by UV–Vis spectroscopy, XRD and TEM. UV–Vis spectrum clearly showed the absorption peak at 520 nm, which is due to the surface Plasmon resonance on AuNPs. XRD analysis highlighted the crystalline nature of AuNPs, with face-centered cubic structure. TEM showed that spherical shape of nanoparticles, with average particles size of 10–20 nm. AuNPs did not show any inhibitory activity both on Gram-positive and Gram-negative bacteria. Furthermore, different doses of AuNPs (0, 100, 500 and 1000 µM) were tested to assess their potential impact on mitotic division and pollen germination. A treatment with 100 µM of AuNPs significantly induced both mitotic division and pollen germination. In the plant cells, the passive uptake of AuNPs through cytosol allowed them to move towards the nuclear pore complex. Subsequently, they interacted with histone protein leading to mitotic cell division and pollen germination. Overall, our study highlighted the potential of gum-fabricated AuNPs in cytogenetic, gene expression and plant tissue culture applications.