Fabrication Of Noble Metal Nanoparticles Research Articles

Effects of anionic and cationic surfactants on the surface Plasmon resonance intensity of biogenic silver nanoparticles: Stability, and position of optical band

Fabrication of noble metal nanoparticles by using green plant extract as reducing agent have been the subject of various investigators due to their enhanced plasmonic properties for various applications. This paper describes the effects of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) on the nucleation of silver sols formation by using coriander seeds extract and silver nitrate redox reaction. The wavelength maxima (λmax) were blue shifted from 433 nm to 425, 423, and 420 nm, respectively, with 0.0, 0.4, 1.0, and 1.6 mM CTAB. The blue and red shifts were also observed from 433 nm to 421, 421, 418, and 438 with 0.0, 0.4, 1.0, 1.6 and 2.0 mM SDS, respectively. The pre-micellar inhibition, and post-micellar catalytic effects were observed on the formation of silver sols with cationic CTAB surfactant. SDS exhibits inhibitory effect on the nucleation rate for an entire range of concentration. Additionally, antioxidant activity in vitro revealed that the percentage scavenging with 2,2-diphenyl-1-picrylhydrazyl (DPPH•) were depended on the dose of AgNPs.

Silver-platinum bimetallic nanoparticles as heterogeneous persulfate activator for the oxidation of malachite green

Fabrication of noble metal nanoparticles by using green chemical method with plant extract as reducing agent to the in situ oxidation toxic water contaminants have been the subject of various investigators due to their enhanced catalytic efficiencies. This paper describes the extraction of caffeic acid from Artemisia herba-alba aqueous extract, and preparation of silver (Ag), platinum (Pt), and silver-platinum (Ag-Pt) nanoparticles with caffeic acid as a reducing and capping agent. The as-prepared Ag-Pt NPs was used as a heterogeneous activator of persulphate (K2S2O8) for the in situ chemical oxidation of malachite green (MG). The Ag-Pt NPs shows no surface Plasmon resonance absorption band. The malachite green dye was completely decolorized in presence of Ag-Pt/K2S2O8 system. SO4-• and HO• radicals generated by the cleavage of S2O82- peroxide activation with Ag-Pt were responsible for the MG decolorization as well as mineralization. The Ag-Pt NPs acted as a sacrificial electron donor. The Ag-Pt NPs were characterized by using conventional techniques such as, UV–visible, FTIR, SEM, TEM, EDX, XPS, and XRD spectroscopic methods.

Piper betle: Augmented Synthesis of Gold Nanoparticles and Its In-vitro Cytotoxicity Assessment on HeLa and HEK293 Cells

Plant-based photo fabrication of noble metal nanoparticles is a dominating research area in nanobiotechnology as they offer immense applications in biomedicine, drug delivery and bioimaging. In this study, we report the synthesis of gold nanoparticles (GNPs) using Piper betle leaf extract. Extraction of secondary metabolites was performed by both acetonic and ethanolic extract to establish a comparative assessment. UV–Visible spectroscopic, Transmission Electron Microscopy, Energy Dispersive X-ray and X-ray diffraction characterization confirmed the synthesis of GNPs. The results thus suggested that the metabolites of P. betle L. leaf can effectively catalyze the conversion of Au3+ to Au0 ions and serve as excellent stabilizing agents. Morphological modulation was found with varying tetrachloroauric acid concentration and the solvent medium used. Cytotoxicity assessment of GNPs on HeLa and HEK293 signified the selective toxic behaviour of GNPs towards cancerous cell lines. Further, biocompatibility towards HEK293 cells signified that the GNPs can be used for drug delivery as well as bio-imaging applications.

Bio-synthesis and structural characterization of highly stable silver nanoparticles decorated on a sustainable bio-composite for catalytic reduction of nitroarenes

Bio-polymers are the most significant natural alternative stabilizers compared to their synthetic counterparts for fabrication of noble metal nanoparticles because of their higher thermal stability, renewability, low cost, eco-friendliness, strong mechanical capacity, and biodegradability properties. Therefore, a new bio-composite (CMC-Pct-AG), which is consisted of sodium carboxymethyl cellulose, agar, and pectin natural biopolymers, was fabricated as an immobilizing agent in this study. Then, highly stable silver nanoparticles (Ag NPs@CMC-AG-Pct) were successfully decorated on the surface of designed CMC-Pct-AG without the use of any hazardous reducing agents, and their chemical structures were illuminated with Uv–Vis, FT-IR, TG/DTG, SEM, EDS, XRD, and ICP-OES analyses. Subsequently, the catalytic performance of Ag NPs@CMC-AG-Pct was studied in the reduction of various nitroarenes in the presence of NaBH4 at room temperature. These tests indicate that Ag NPs@CMC-AG-Pct is an efficient catalyst which converts nitroarenes to desired amines with good yields and short reaction times. Reproducibility of the catalyst was also investigated, and it is found that Ag NPs@CMC-AG-Pct served several times as a retrievable and reusable catalyst for catalytic reduction of nitroarenes.

Biogenic fabrication of gold nanoparticles using Camellia japonica L. leaf extract and its biological evaluation

Development of green technique for the fabrication of noble metal nanoparticles is of great importance in order to avoid the usage of toxic chemicals. In this strategy, gold nanoparticles (AuNPs) are synthesized at room temperature by using Camellia japonica leaf extract under room temperature. The successful formation of AuNPs was confirmed by various spectroscopic techniques including UV, FTIR, XRD and SEM studies. The resulting antimicrobial activity of the synthesized AuNPs stabilized in C. japonica is tested against seven different microbial strains such as Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. The present study opens a new window for future synthesis of AuNPs via green technique.

One pot synthesis of dandelion-like polyaniline coated gold nanoparticles composites for electrochemical sensing applications

In this work, we report a facile and green strategy for one pot and in-situ synthesis of a dandelion-like conductive polyaniline coated gold nanoparticle nanocomposites (Au@PANI). The Au@PANI was characterized by SEM, TEM, XRD, TGA, FTIR, UV–vis and conductivity measurement, respectively. Newly-designed Au@PANI materials possessed a significantly high conductivity and strong adsorption capability. Thus, the Au@PANI modified glassy carbon electrode (GCE) was utilized for construct a novel electrochemical sensor for the simultaneous assay of Pb2+ and Cu2+ using square wave anodic stripping voltammetry (SWASV). Under the optimized conditions, an excellent electrochemical response in the simultaneous of Pb2+ and Cu2+ with detection limit of 0.003 and 0.008 μM (S/N = 3), respectively. Moreover, the prepared sensors realized an excellent reproducibility, repeatability and long term stability, as well as reliable practical assays in real water samples. Besides, the possible formation mechanism and sensing mechanism of Au@PANI nanocomposites have been discussed in detail. We believe this study provides a novel method of fabrication of noble metal nanoparticles decorated conducting polymer materials for the electrochemical sensing applications.

A simple plasma reduction for synthesis of Au and Pd nanoparticles at room temperature

A simple and fast plasma reduction method is developed for synthesis of Au and Pd metal nanoparticles. The scanning electron microscopy (SEM) analysis indicates a formation of aggregates of Au and Pd nanoparticles with branched structure. The transmission electron microscopy (TEM) image shows that the inclusive nanoparticles are all about 5nm in size. Compared to conventional hydrogen reduction method, plasma method inhibits the agglomeration of metal particles. The room temperature operation is very helpful to limit the nanoparticle size. Most interestingly, plasma reduction produces more flattened metal particles. This plasma reduction does not require the use of any hazardous reducing chemicals, showing the great potential for the fabrication of noble metal nanoparticles.

Controlled fabrication of noble metal nanoparticles loaded on the surfaces of cyclotriphosphazene-containing polymer nanotubes

We report on the fabrication of noble metal nanoparticles loaded on the surfaces of cross-linked poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanotubes of high stability. PZS nanotubes were first synthesized by precipitation polymerization between hexachlorocyclotriphosphazene and 4,4′-sulfonyldiphenol based on in situ template mechanism. Then the PZS nanotubes were directly used as scafford to load metal Au, Ag, and Pd nanoparticles, respectively, through cation complexation followed by gentle reduction. The structure and morphology of the metal/PZS nanocomposites were determined by means of Fourier transform infrared spectra, energy dispersive X-ray spectroscopy, elemental analysis, X-ray diffraction, scanning electron microscope, transmission electron microscope, and thermogravimetric analysis (TGA). Results showed that the metal/PZS nanocomposites possessed 460 °C of initial thermal decomposition temperature under air atmosphere and the loading amount of metal nanoparticles on the PZS nanotube surfaces could be controlled easily. As-fabricated metal/PZS nanocomposites are expected to have potential applications in catalysis.

Facile fabrication of noble metal nanoparticles encapsulated in hollow silica with radially oriented mesopores: multiple roles of the N-lauroylsarcosine sodium surfactant

A facile one-pot method was reported to fabricate noble metal nanoparticles encapsulated in silica hollow nanospheres with radially oriented mesopores, and the anionic amino acid surfactant, N-lauroylsarcosine sodium, played multiple roles: reducing agent, stabilizer, emulsion droplets and mesopore template.