Formation Of AuNPs Research Articles

Thuja occidentalis mediated AuNPs as wound dressing agents for abdominal wound healing in nursing care after surgery

Prevention of infection at the surgical area and outbreak of wounds are the most important and at the same time challenging tasks in clinical care. This research investigates the healing effect of laparotomy wounds after the use of bio-fabricated gold nanoparticles (Au NPs) prepared utilizing Thuja occidentalis leaf extract. Ultraviolet–visible (UV–Vis) spectroscopy and X-ray diffraction (X-RD) results confirmed the successful formation of Au NPs. High-resolution Transmission Electron Microscopy (HR-TEM) images confirmed the formation of spherical shaped Au NPs comprising of 30–50 nm particle size. Dermal fibroblasts were subjected to increased concentrations of Au NPs and their effect of cytotoxicity and synthesis of collagen was evaluated. The procedure of celiotomy was conducted on rabbits where the surgical area was exposed topically with either vehicle or once/everyday with Au NPs for about 14 days. Au NPs raised the collagen production from dermal fibroblasts and improved the expression of caspase 3 by exposure to a long period. AuNPs also showed cytotoxic impact with half-maximal inhibitory concentration (IC50) of 0.16 mg/mL. Regular treatment of surgical area with AuNPs led to higher collagen deposition with reduced microbial load and enhanced healing of wounds.

Rapid mycosynthesis and characterization of phenols-capped crystal gold nanoparticles from Ganoderma applanatum, Ganodermataceae

Abstract This study aims to mycosynthesize crystal gold nanoparticles (AuNPs) using phenolic compounds isolated from Ganoderma applanatum (Reishi mushroom). The phenols-capped AuNPs were described by change of color, UV–Vis, FTIR, AFM, FESEM, TEM, HRTEM, SAED, EDX, XRD and Zeta Potential analyses. HPLC and FTIR analyses exhibited the presence of some phenolic compounds including rutin, qurcetine, epigene, keampherol, and gallic acid. The mycosynthesized AuNPs were capped by phenols as a reducer and stabilizer agent as in FTIR, and Zeta Potential. The lambda max of UV–Vis (550 nm) and EDX results proved the formation of AuNPs after 10 min. AFM, FESEM, TEM, HRTEM, and SAED images showed face-centered cubic crystals (phenols-capped AuNPs) with average 18.70 nm. The mycosynthesized phenols-capped AuNPs exhibited rapid catalytic reduction of methylene blue dye to leucomethylene blue in the existence of NaBH4. This study is considered first attempt to mycosynthsize of AuNPs using phenols isolated from edible mushrooms which showed significant rapid role to decolorize MB dye.

Optical, Structural, and Antimicrobial Study of Gold nanoparticles Synthesized Using an Aqueous Extract of Mimusops elengi Raw Fruits

Gold nanoparticles (AuNPs) has been synthesized via a green route using an aqueous extract of Mimusops elengi raw fruits. The phytochemicals of the fruit help in stabilizing and capping of the nanoparticles. The formation and stability of the synthesized samples has been explained based on results that we obtain from UV-Visible spectroscopy, Fourier Transform Infra-Red (FTIR) spectroscopy, Dynamic Light Scattering (DLS), X-ray diffraction (XRD), scanning electron microscopy (SEM). Further, the positive results of the antimicrobial test add one more novelty to this work. The axiom of this work is the synthesis of stable AuNPs without using any external stabilizing or reducing agents. The formation of AuNPs with the help of photochemical present in Mimusops elengi is yet another important aspect of this work, which provides an eco-friendly method for the synthesis of AuNPs, which can be used extensively because of its non-hazardous condition.

Experimental Investigations on Behaviour of Rhamnolipid Biosurfactant as a Green Stabilizer for the Biological Synthesis of Gold Nanoparticles

Use of biosurfactant as a stabilizer for the biological synthesis of gold nanoparticles (AuNPs) is now emerging as a nontoxic and environmentally acceptable green chemistry procedure. Stability of AuNPs at different pHs is very important because our body has different pHs. This paper addresses this issue. In this work, first P. aeruginosa PTCC 13401 was used to produce rhamnolipid biosurfactant. The highest rhamnolipid production occurred at 120 h, achieving a value of 3.1 g/L. The thin layer chromatography (TLC) indicated that the crude product is a mixture of mono-rhamnolipid and di-rhamnolipid with retardation factor (Rf) value of about 0.35 and 0.78, respectively. Moreover, rhamnolipid solutions with different pHs were added to HAuCl4 solution and incubated for 24 h at 37 oC and 150 rpm. The formation of spherical AuNPs was monitored using a UV–vis spectrophotometer and verified by TEM. Our results showed that the formation of AuNPs occurred just for pH values between 7.0 -8.0. Measurement of the surface tension of the solution at different pH values was performed to find out the reason for this observation. Our results showed that the surface tension was also stable only between pH 7.0-8.0. This was inferred from precipitation of rhamnolipid at higher and lower pH values. The results of this work may help pharmacists to have a good prediction of behavior of rhamnolipid biosurfactants as a stabilizer for biomedical applications including tissue engineering and drug delivery.

Bio fabrication of gold nanoparticles and their combination with chemotherapy and ultrasound for effective treatment of tumors

Chemotherapy is one of the important medical option for the cancer therapy, but still new combination of therapeutic treatment methods are needed to achieve efficient anti tumor activity. In this work, Pueraria lobata leaf extract was utilized as a bio reductant for the fabrication of the Gold nanoparticles (Au-NPs) by an ecological approach without using any harmful chemical. This work also evaluates whether the combined effect of chemotherapy along with Au-NPs and Ultrasound (US) is effective over the tumors or not. About 10 mL of plant extract was added to 1mM of HAuCl4 solution (20.0 mL) and pH was maintained at 12 and allowed for stirring for half an hour. The change in solution color from yellow to purple signified the Au-NPs formation. XRD results and TEM images confirmed the formation of crystalline Au-NPs with sizes ranging from 23-30 nm. Further, biological studies revealed that the combination of Au-NPs and US along with chemotherapy improved the impact of anti-cancer drug. In conclusion, Pueraria lobata leaf extract mediated synthesis of Au-NPs by an eco-friendly approach was reported in this work. The plant biomolecules of the extract were involved in the reduction and capping of the Au-NPs formed. The major conclusion is that addition of Au-NPs with chemotherapy and ultrasound has shown more effective anti-tumor activity.

Fabrication of an electrochemical sensing platform based on hydrophilic carbon/gold nanoparticles composite

A simple, economical, and environmentally friendly strategy for the one-pot preparation of a nanocomposite made up of gold nanoparticles and Electrogenerated Hydrophilic Carbon material (EHC), is reported in this work. The EHC material works itself as the reducing agent and conductive carbon material support. The formation of AuNPs was confirmed by UV–visible spectroscopy and transmission electron microscopy. It was demonstrated that after the nanocomposite immobilization on a substrate, the EHC material can be easily removed due to its outstanding solubility in water. This procedure was exemplified for the modification of a glassy carbon electrode, resulting in a bare AuNPs/GC electrode. The cyclic voltammetry was used to evaluate the effectiveness of AuNPs immobilization on the electrode and to track the dependence of the electroactive surface area and Au loading with the reaction mixture composition (HAuCl4/EHC). The potential of the AuNPs and nanocomposite-modified electrodes as sensor platforms for medical and biological applications was exemplified by their performance for the oxygen reduction reaction in a phosphate buffer saline solution.

Green synthesis of non-spherical gold nanoparticles using Solidago canadensis L. extract

In the present article, we reported the application of the extract of leaves from Solidago canadensis L. for the green synthesis of triangular and hexagonal gold nanoparticles (AuNPs). The phytochemical characterization, by reaction with HAuCl4 solutions, showed that the extract of Solidago canadensis L. contained the secondary metabolites that can act both as reducing and as stabilizing agents. For the synthesis of AuNPs, the effects of the HAuCl4 concentration (0.25–0.975 mM) and the reaction time (10–180 min) were investigated. The formation of AuNPs is confirmed by the color change from yellowish to purple-red. Photoluminescence measurements of Au nanocolloids showed a continuous emission band ranging from violet to red. UV–Vis characterization of AuNPs in the prepared nanocolloids showed surface plasmon resonance peaks at 530 and > 870 nm. TEM revealed that the AuNPs are in the range of 8–200 nm, they have spherical, triangular, and hexagonal forms of varying sizes. AFM and STM showed a non-ideal relief of large triangular and hexagonal gold nanoprisms. The EDX analysis, XRD and SAED patterns confirmed the face-center cubic structure of AuNPs.

Rapid One-Pot Synthesis of Polydopamine Encapsulated Carbon Anchored with Au Nanoparticles: Versatile Electrocatalysts for Chloramphenicol and Folic Acid Sensors.

Designing and engineering nanocomposites with tailored physiochemical properties through teaming distinct components is a straightforward strategy to yield multifunctional materials. Here, we describe a rapid, economical, and green one-pot microwave synthetic procedure for the preparation of ternary nanocomposites carbon/polydopamine/Au nanoparticles (C/PDA/AuNPs; C = carbon nanotubes (CNTs), reduced graphene oxide (rGO)). No harsh reaction conditions were used in the method, as are used in conventional hydrothermal or high-temperature methods. The PDA unit acts as a non-covalent functionalizing agent for carbon, through π stacking interactions, and also as a stabilizing agent for the formation of AuNPs. The CNTs/PDA/AuNPs modified electrode exhibited excellent electrocatalytic activity to oxidize chloramphenicol and the resulting sensor exhibited a low detection limit (36 nM), wide linear range (0.1–534 μM), good selectivity (against 5-fold excess levels of interferences), appreciable reproducibility (3.47%), good stability (94.7%), and practicality (recoveries 95.0%–98.4%). Likewise, rGO/PDA/AuNPs was used to fabricate a sensitive folic acid sensor, which exhibits excellent analytical parameters, including wide linear range (0.1–905 μM) and low detection limit (25 nM). The described synthetic route includes fast reaction time (5 min) and a readily available household microwave heating device, which has the potential to significantly contribute to the current state of the field.

Characterization of Biocompatible Gold Nanoparticles Synthesized by using Curcuma xanthorrhiza and their Catalytic Activity

Background: Based on various distinguished physical and chemical properties of gold nanoparticles, they have far wide applications in several areas of industry and medicine, such as catalysis, bio-sensor and drug delivery. Compared to a chemical method, biological synthesis is an economical and less toxic process, thus it is a better alternative for nanoparticle synthesis. In this study, an environmentally friendly method was chosen to produce AuNPs using Curcuma xanthorrhiza. Methods: Alkaline aqueous extract of C. xanthorrhiza rhizomes, which acts as a reducing and stabilizing agent was used to produce AuNPs by bio-reduction of HAuCl4. The formation of AuNPs was periodically monitored by UV-visible spectroscopy. The obtained AuNPs were characterized by Xray diffraction, energy dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared (FTIR) spectroscopy. Catalytic activity and toxicity of the AuNPs were evaluated. Results: The AuNPs obtained from this study mostly were spherical in shape with approximately 15 nm in size. The presence of functional groups derived from C. xanthorrhiza rhizome extract involved in the gold bio-reduction process was confirmed by the spectrum of FTIR spectroscopy. The biosynthesized AuNPs at the concentration of 0.5 μg/ml had catalytic activity in dye degradation of Congo red. The results showed that this biogenic AuNPs did not cause any toxicity to zebrafish embryos and all tested cell lines. Conclusion: The biocompatible AuNPs with catalytic activity were successfully fabricated with C. xanthorrhiza rhizome extract by simple eco-friendly and inexpensive method. This catalytic activity of the obtained AuNPs is potentially useful for industrial applications as well as nanoscience and nanotechnology.

Fluorescent poly(methacryloxy quinolin) microparticles allowing simultaneous gold detection with additive-free photocatalytic synthesis of raspberry-like gold nanoparticles and gold nanoparticle decorated microparticles

Novel, fluorescent polymer particles based on poly(8-methacryloxy quinoline) (PMAQ) have been synthesized via suspension and mini-suspension polymerization with a diameter between 400 nm and 4 µm. Usage of sodium dodecyl sulfate (SDS) co-stabilizer causes formation of smaller microparticles with rough surfaces. Easy, one step and additive free synthesis of gold nanoparticles (AuNPs) is firstly achieved by using these new fluorescent microparticles as electron donor material and stabilizer. It is observed that the surfaces of the microparticles is successfully covered by a self-assembled layer of AuNPs. An evolution for different stages of AuNPs formation on PMAQ microparticles or colloidal raspberry-like AuNPs is offered. Raspberry-like AuNPs consist of hundereds of smaller AuNPs that result in higher surface area. Hovewer, Au nanocrystals on PMAQ are obtained in the last stage of evolution. Gold existense is also detected simultaneously due to its fluorescence quenching property during interaction with microparticles. Moreover UV-light assisted AuNPs synthesis on the PMAQ microparticles is achived in a quite short time. The Au content of the AuNP-polymer hybrid particles is determined to be 12 wt%with ICP-MS studies. These unique particles are promising candidates for various applications such as in catalysis, biosensor technology, biomedical applications, and easily prepared SERS substrates.

Effect of Reaction Time and Stability Properties of Gold Nanoparticles Synthesized by <i>p</i>-Aminobenzoic Acid and <i>p</i>-Aminosalicylic Acid

In this work, we determined the influenced of the reaction time at the synthesis of gold nanoparticles (AuNPs) by p-aminosalicylic acid and p-aminobenzoic acid as reducing agent. Besides working as a reducing agent, the p-aminobenzoic acid and p-aminosalicylic acid also simultaneously played a role as a capping agent/stabilizing agent. Gold ion was first mixed with the pH adjusted p-aminobenzoic acid and p-aminosalicylic acid. The mixture then heated in boiling water at 86 °C. The formation of AuNPs was indicated by the appearance of red color and analyzed with UV/Vis spectrophotometry to evaluate their surface plasmon resonance (SPR) absorption in the wavelength range 400–800 nm. The reducing ability of the reducing agents was affected by its structure. Gold nanoparticles that were synthesized with p-aminosalicylic acid were more stable, faster and had a smaller size than its counterpart that is synthesized with p-aminobenzoic acid. The stability test over a periods 5 months showed that AuNPs were relatively stable.

Facile synthesis of anisotropic gold nanoparticles and its synergistic effect on breast cancer cell lines.

Gold nanoparticles (AuNPs) possess colourful light-scattering properties due to different composition, size and shape. Their unique physical, optical and chemical properties coupled with advantages, have increased the scope of anisotropic AuNPs in various fields. This study reports a green methodology developed for the synthesis of anisotropic AuNPs. The aqueous extracts of Alternanthera sessilis (PGK), Portulaca oleracea (PAK) and Sterculia foetida (SF) with gold ions produced violet, purple and pink coloured AuNPs, respectively, under sonication and room temperature methods revealing the formation of different shapes of AuNPs. The results of TEM analysis of AuNPs confirmed the formation of triangular plate AuNPs of the size 35 nm for PAK extract. Spherical-shaped AuNPs (10-20 nm) were obtained using an extract of PGK. SF extract produced rod, hexagon, pentagon-shaped AuNPs and nanorice gold particles. The cell viability studies of the PGK, PAK and SF-mediated AuNPs on MCF-7 cell lines by MTT assay revealed the cytotoxic activity of AuNPs to depend on the size, shape and the nature of capping agents. The synthesised AuNPs significantly inhibited the growth of cancer cells (MCF-7) in a concentration-dependent manner. The size and shape of these anisotropic AuNPs also reveal its potency to be used as sensors, catalysis, photothermal and therapeutic agents.

Colorimetric-enzymatic determination of tyramine by generation of gold nanoparticles.

In this paper, it has been demonstrated that Au(III) is able to act instead of O2 in the oxidase enzymatic reaction, so that it becomes reduced to purple gold nanoparticles (AuNPs). The plasmon band (at 540nm) can be used as the analytical signal. Tyramine has been determined using its enzymatic reaction with tyramine oxidase (TAO). The kinetic of the AuNP formation has been studied in the light of both the Avrami equation for crystallization and the Finke-Watsy mechanism for AuNP nucleation and growth. The effects of the Au(III), TAO and tyramine concentrations on the corresponding kinetic constants have beeninvestigated. Working at room temperature, under optimal conditions (phosphate buffer pH7.0, TAO 0.5U.mL-1 Au(III) 1mM), the linear response ranges from 2.5 × 10-5 M to 3.3 × 10-4 M Tyramine (5.6% RSD) and the LOD is 2.9 × 10-6 M. Under theseconditions, the signal is measured after 30min reaction (to obtain the highest sensitivity), but this time can be significantly reduced by increasing the temperature (the reaction is finished after 4min whenworking at 50°C). The method has been applied to tyramine determination in a cheese sample with good results. The new scheme proposed in this paper can be extended, in principle, to other enzymatic methods based on oxidase enzymes. Graphical abstractTyramine is determined by measuring the plasmon band of the gold nanoparticles formed during its enzymatic reaction with Tyramine oxidase. Moreover, a mathematical model has been developed to explain the formation of the gold nanoparticles during the reaction.

From spherical to bone-shaped gold nanoparticles-Time factor in the formation of Au NPs, their optical and photothermal properties.

Using the same synthesis method, which was stopped at different time intervals, gold nanoparticles (Au NPs) with different shapes, from spherical to bone-shaped, were obtained. The physical properties of the synthesized Au NPs were investigated using transmission electron microscopy (TEM) combined with selected area electron diffraction patterns (SAED) and ultraviolet-visible spectroscopy (UV-vis). The TEM images showed, that stopping the synthesis after one minute lead to the formation of small spherical Au NPs, which evolved to the cubic shape, rods and bone-shaped Au NPs after 15 min, 30 min, 2 h, respectively. SAED patterns showed, that all the obtained Au NPs were crystalline. UV-vis spectra revealed, that the light absorbance depends on the shape of the Au NPs. Moreover, the effects of the time factor in the formation of Au NPs on the effective conversion of electromagnetic energy into thermal energy, was studied. Furthermore, simulated photothermal therapy (PTT) in combination with the obtained NPs, was done for two cancer cell lines SW480 and SW620. The mortality of cells after using the differently shaped Au NPs as photosensitizers is between 18 % and 52 % and increases with the decrease of the synthesis time.

Biogenic synthesis of gold nanoparticles using Commiphora wightii and their cytotoxic effects on breast cancer cell line (MCF-7)

The current study aimed at developing gold nanoparticles (AuNPs) using the aqueous extract of the medicinal plant Commiphora wightii. The phytosynthesized gold nanoparticles (Cw@AuNPs) were evaluated for their anticancer activity against MCF-7 breast cancer cell model. The formation of AuNPs by Commiphora wightii leaf extract was confirmed by UV–vis spectra where their surface plasmon resonance was found at 533 nm. Further characterization of Cw@AuNPs was done by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, and fourier-transform infrared spectroscopy (FTIR) analysis. In vitro anticancer potential of thus obtained AuNPs was evaluated against MCF-7 and where the IC50 was found to be 66.11 μg/mL Further, apoptotic studies were carried out using ethidium bromide dual staining, DNA fragmentation, comet assay, and flow cytometry studies. Results revealed that Cw@AuNPs at higher concentration significantly increased the apoptotic cells when compared to control cells. Cell cycle analysis of MCF-7 cells confirmed the cell cycle arrest at G2/M phase. These results demonstrate that the biosynthesized Cw@AuNPs appear to be promising for therapeutical applications against breast cancer.

A network composed of gold nanoparticles and a poly(vinyl alcohol) hydrogel for colorimetric determination of ceftriaxone.

A hydrogel network was prepared from poly(vinyl alcohol) (PVA) and borax, and then was modified with gold nanoparticles (AuNPs) that were obtained by in-situ nucleation and growth. This modified network is shown to be a viable optical nanoprobe for the drug ceftriaxone (CTRX) in biological samples. The properties and morphology of the modified network were investigated using energy dispersive X-ray analysis, transmission electron microscopy, zeta-sizing and viscosimetry. The UV-vis spectrum was recorded to verify the nanosynthesis of the red AuNPs, and the maximum absorption is found at 517nm. This AuNP-poly(vinyl alcohol)-borax hydrogel nanoprobe (AuNP/PBH) is introduced as an optical nanoprobe for ceftriaxone in biological samples. The AuNPs have a better ability to attach the sulfur functional groups than amino functional groups. Hence, the probable mechanism is based on the attachment of sulfur functional groups of CRTX structure with AuNPs located in the PBH. As a result of this interaction, the surface plasmon resonance of AuNPs is altered in the presence of CTRX and the absorption of the nanoprobe is decreased at 517nm. The effects of pH value, borax and PVA concentration were investigated. Under optimum conditions, the calibration graph is linear in the 1-90μgmL-1 CTRX concentration range, and the limit of detection is 0.33μgmL-1. The relative standard deviation for ten replicate measurements of at levels of 20 and 70μgmL-1 of CTRX was 4.0% and 2.2%, respectively. The nanoprobe was successfully applied to the determination of CTRX in (spiked) serum and urine samples. The performance of the nanoprobe was compared with HPLC method and the results were satisfactory. Graphical abstract Schematic representation of a new nanoprobe based on in situ formation of AuNPs into poly(vinyl alcohol) (PVA)-borax (PBH) hydrogel fabricated for ceftriaxone detection. The hydrogel acts as the reducing agent for production and embedding of AuNPs in the network.

Cephradine-Capped Gold Nanoparticle Modified Glassy Carbon Electrode for Trace Level Sensing of Triphenyltin Hydroxide

Synthesis of highly stable gold nanoparticles (AuNps) was accomplished using cephradine (Cep) drug as the capping molecule and sodium borohydride as the reducing agent. Characterization studies such as ultraviolet-visible (UV–vis) spectroscopy confirmed the formation of AuNps while fourier transform infra-red (FT-IR) spectroscopy showed the interaction of AuNps with Cep. The size and shape of Cep-AuNps were investigated using atomic force microscopy (AFM) while their crystallinity was determined through X-ray diffractometry (XRD). The synthesized Cep-AuNps, after getting deposited on a glassy carbon electrode (GCE), proved as a highly responsive sensor for low-level detection of triphenyltin hydroxide (TPTH) using cyclic voltammetry (CV) as the determining mode in stirred solution. The developed sensor linearly responded to TPTH in the range of 1–80 nM with a lower detection limit (LDL) of 0.12 nM and R2 value of 0.9948 under optimized conditions. Importantly, the sensor was highly stable and reproducible, showing a relative standard deviation (RSD) value of 1.1% based on 15 replicative runs and proved to be extremely selective for TPTH with negligible interference in the presence of expected interfering species. The developed sensor was effectively utilized for monitoring TPTH in natural water samples.

Biosynthesis of gold nanoparticles (AuNPs) by marine baitworm Marphysa moribidii idris, hutchings and arshad 2014 (annelida: polychaeta) and its antibacterial activity

Gold nanoparticles (AuNPs) have unique and outstanding optical properties that can be applied in various applications. The current productions of AuNPs are cumbersome owing to the use of reducing agents which are highly reactive and toxic in nature. Hence, a biogenic synthesis of AuNPs by exploiting local marine baitworm (Polychaeta), Marphysa moribidii as potential reducing agents was conducted. AuNPs were biosynthesised by using different masses of polychaete extracts (5, 10, 15, and 20 g) and observed up to 3 months. The formation of AuNPs was confirmed by the appearance of red-ruby colour and the presence of surface plasmon resonance (SPR) absorption peaks (548–563 nm) from UV-Vis spectroscopy. The AuNPs were in spherical-like shapes with large aggregations based on scanning electron microscope (SEM). The average particle size and morphology of AuNPs were confirmed using transmission electron microscopy (TEM) (30–150 nm) and dynamic light scattering (DLS) (20–100 nm). Fourier transformed infrared (FTIR) analysis and X-ray diffraction (XRD) were carried out on polychaete extracts to explore the functional groups existing and also to prove the absence of AuNPs in them. Lastly, the antibacterial assessment of AuNPs was examined using Kirby-Bauer disc diffusion method and revealed the exhibition of antibacterial activity on both Gram-positive and Gram-negative bacteria.

Microwave assisted synthesis of gold nanoparticles with Phyla nodiflora (L.) Greene leaves extract and its studies of catalytic reduction of organic pollutants

The synthesis of gold nanoparticles (AuNPs) has drawn attention over the past few years owing to their optical and physico-chemical properties. In this work, AuNPs were synthesized using Phyla nodiflora (L.) leaf extract by microwave irradiation method. This leaf extract act as reducing and stabilizing agent. The concentrations of Phyla nodiflora (L.) Greene leaf extract, HAuCl4 and duration of microwave irradiation were optimized for the better yield of AuNPs. The AuNPs formation was confirmed by different analytical techniques like UV–Vis spectrophotometry (UV), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM). Under the optimal synthetic conditions, the average diameter and zeta potential of AuNPs synthesized were 10 ± 2 nm and −24.0 mV respectively. Phytochemicals present in the extract help to reduce Au+3 to Au0 and act as a stabilizer in the synthesis of AuNPs. Afterwards, the catalytic activity of AuNPs was studied in NaBH4 assisted reduction of p-nitrophenol (4-NP), Congo Red (CR) and Methylene Blue (MB). Thus, AuNPs synthesized with leaf extract could be an excellent catalyst for 4-NP, CR and MB in chemical industries.

Antioxidant activity of environmentally - friendly noble metallic nanoparticles

This research paper presents the environmentally - friendly synthesis of two noble metallic nanoparticles, namely silver (AgNPs) and gold (AuNPs), from ten different plants with proven pharmaceutical benefits, e.g.: Sea buckthorn, Elderflower, Lungwort, Acacia, Cornflower, Ramson, etc. Both AgNPs and AuNPs are prepared via two routes: at room temperature, in the dark, for 24 hours and at 50°C under a constant stirring of 600 rpm for 30 minutes. UV - Vis spectroscopy was used to investigate the formation of both AgNPs and AuNPs and compared to the UV – Vis spectra of the plain aqueous extracts prepared at 4°C. The main purpose of our research was to investigate the antioxidant activity of the aqueous extracts and noble metallic nanoparticles obtained thereof and to determine whether the temperature-conducted environmentally - friendly synthesis of AgNPs and AuNPs influences the antioxidant activity in any way.