Brajesh Kumar

Sonochemical Synthesis of Silver Nanoparticles Using Starch: A Comparison

A novel approach was applied to synthesize silver nanoparticles using starch under sonication. Colloidal silver nanoparticles solution exhibited an increase of absorption from 420 to 440 nm with increase starch quantity. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, amorphous, silver nanoparticles of diameter ranging from 23 to 97 nm with mean particle size of 45.6 nm. Selected area electron diffraction (SAED) confirmed partial crystalline and amorphous nature of silver nanoparticles. Silver nanoparticles synthesized in this manner can be used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications. The optimized reaction conditions include 10 ml of 1 mM AgNO3, 25 mg starch, 11 pH range, and sonication for 20 min at room temperature.

Green synthesis of silver nanoparticles using Andean blackberry fruit extract

Green synthesis of nanoparticles using various plant materials opens a new scope for the phytochemist and discourages the use of toxic chemicals. In this article, we report an eco-friendly and low-cost method for the synthesis of silver nanoparticles (AgNPs) using Andean blackberry fruit extracts as both a reducing and capping agent. The green synthesized AgNPs were characterized by various analytical instruments like UV–visible, transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The formation of AgNPs was analyzed by UV–vis spectroscopy at λmax = 435 nm. TEM analysis of AgNPs showed the formation of a crystalline, spherical shape and 12–50 nm size, whereas XRD peaks at 38.04°, 44.06°, 64.34° and 77.17° confirmed the crystalline nature of AgNPs. FTIR analysis was done to identify the functional groups responsible for the synthesis of the AgNPs. Furthermore, it was found that the AgNPs showed good antioxidant efficacy (>78%, 0.1 mM) against 1,1-diphenyl-2-picrylhydrazyl. The process of synthesis is environmentally compatible and the synthesized AgNPs could be a promising candidate for many biomedical applications.

One pot phytosynthesis of gold nanoparticles using Genipa americana fruit extract and its biological applications.

In this article, rapid one pot synthesis of gold nanoparticles (GNPs) using an eco-friendly extract of Genipa americana L. fruit is described. Electrospray ionization mass spectrometry (ESI-MS) and Fourier transform infrared (FTIR) spectroscopic studies demonstrated that small molecules such as genipin, genipaol, geniposide and ranolazine can act as reducer as well as stabilizers. The monodispersed, spherical GNPs were further characterized by UV-vis spectroscopy at λmax=535 nm, transmission electron microscopy (TEM), dynamic light scattering (DLS) and X-ray diffraction (XRD) analysis. This synthetic approach offers a greener and alternate route to the preparation of GNPs free from toxic chemical components and stable for 6-7 months under room temperature. The green synthesized GNPs showed weak antioxidant efficacy against 1,1-diphenyl-2-picrylhydrazyl and no cytotoxicity against A-549 and HeLa human cancer cell lines, from lung and cervix. This study opens a new industrial scope of G. americana fruit in nanoscience and as surface modified GNPs can be developed into a successful drug carrier for future pharmaceutical products.

In Vitro Evaluation of Selected Benzimidazole Derivatives as an Antioxidant and Xanthine Oxidase Inhibitors

2‐Aryl‐1‐arylmethyl‐1H‐benzimidazole derivatives having different side chains on the structure were examined in vitro for their antioxidant abilities by 2,2‐diphenyl‐1‐picryl hydrazine radical scavenging activity, reducing ability, OH radical scavenging activity, inhibition of polyphenol oxidase and xanthine oxidase. Overall, with few exceptions, all the 2‐aryl‐1‐arylmethyl‐1H‐benzimidazoles showed moderate biological activity with all parameters examined. The 2‐aryl‐1‐arylmethyl‐1H‐benzimidazoles were found to be reactive toward 2,2‐diphenyl‐1‐picryl hydrazine radical and had considerable reducing ability, with significant xanthine oxidase inhibition. With few exceptions, all the compounds under study were found to possess moderate‐to‐poor OH radical scavenging activity and inhibited polyphenol oxidase significantly. These findings suggest that these 2‐aryl‐1‐arylmethyl‐1H‐benzimidazoles can be considered as potential antioxidant and xanthine oxidase inhibitory agents, those might be further, explored for the design of lead antioxidant and antigout drug candidates using in vivo trials.

Green Approach for Fabrication and Applications of Zinc Oxide Nanoparticles

Zinc oxide nanoparticles (ZnO-NPs) are known to be one of the multifunctional inorganic compounds which are widely used in everyday applications. This study aims to fabricate ZnO-NPs using grapefruit (Citrus paradisi) peel extract with particle size ranging from 12 to 72 nm. Structural, morphological, and optical properties of the synthesized nanoparticles have been characterized by using UV-Vis spectrophotometer, TEM, DLS, and FTIR analysis. They show the significant photocatalytic degradation efficiency (>56%, 10 mg/L, 6 h) against methylene blue and antioxidant efficacy (≥80% for 1.2 mM) against 1,1-diphenyl-2-picrylhydrazyl. From the results obtained it is suggested that green ZnO-NPs could be used effectively in environmental safety applications and also can address future medical concerns.

Lantana camara berry for the synthesis of silver nanoparticles

ABSTRACT Objective To synthesize the silver nanoparticles (AgNPs) by reduction of silver ions into nano silver, using ripened berry extract of Lantana camara and evaluate its antioxidant activity against 1, 1-diphenyl-2- picrylhydrazyl. Methods The prepared AgNPs were characterized by visual, UV-visible spectrophotometer, dynamic light scattering and transmission electron microscopy with selected area electron diffraction. Results Transmission electron microscopy and dynamic light scattering analysis confirmed the AgNPs are spherical and 75.2 nm average sized. Selected area electron diffraction analysis supports that the obtained nanoparticles were in crystalline form. In addition, the antioxidant efficacy of prepared AgNPs was found to be higher than berry extract against 1, 1-diphenyl-2- picrylhydrazyl. Conclusions From the results obtained it is suggested that surface modified AgNPs at lower concentration, showed higher antioxidant activity than berry extract against 1, 1-diphenyl-2- picrylhydrazyl and could be used effectively in future ethno pharmacological concerns.

In vitro evaluation of silver nanoparticles cytotoxicity on Hepatic cancer (Hep-G2) cell line and their antioxidant activity: Green approach for fabrication and application.

In this article, biosynthesis of silver nanoparticles (AgNPs) using Andean Mora (Rubus glaucus Benth.) leaf has been reported. Different analytical techniques including UV-vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used for the characterization of AgNPs. The initial appearance of color change with the intense surface plasmon resonance (SPR) bands around 440-455 in UV-visible spectra revealing the formation of AgNPs. The TEM image showed the AgNPs to be anisotropic, quasi-spherical in shape with sizes in the range of 12-50nm. On the other hand, XRD studies revealed the formation of face-centered cubic structure for AgNPs. The surface modified AgNPs showed no cytotoxicity at the concentration ranging from 0.01μM to 1.0μM on the Hepatic cancer (Hep-G2) cell line and observed antioxidant efficacy >70% at the concentration 0.05mM/0.20mL against 1, 1-diphenyl-2-picrylhydrazyl. From the results obtained it is suggested that AgNPs could be used effectively in future drug delivery systems and other biomedical concerns.

Direct spectrophotometric determination of trace amounts of mercury(II) in aqueous media as its dithizonate complex in the presence of a neutral surfactant

The spectrophotometric determination of mercury in aqueous solution as its dithizonate complex in the presence of Triton X-100, a neutral surfactant that renders both the ligand and the complex water soluble, is described. The molar absorptivity, specific absorptivity and Sandell sensitivity of the complex at the wavelength of maximum absorption (490 nm) were found to be 3.868 × 104 l mol–1 cm–1, 192.8 l g–1 and 5.2 ng cm–2, respectively. Beers law was obeyed between 1 × 10–6 and 2 × 10–5M Hg2+. The interference caused by the presence of a number of common cations and anions was studied and the method was applied successfully to the analysis of a mercury-based pesticide.

Biofabrication of nanogold from the flower extracts of Lantana camara.

The present investigation was done to explore the potential of Lantana camara (L. camara) flower in the fabrication of gold nanoparticles (AuNPs). The shape and size of AuNPs have been successfully controlled by introducing small amounts of L. camara flower extract. It produced spherical nanogold of average size 10.6 ± 2.9 nm without any aggregation and showed significant photocatalytic degradation activity of the methylene blue (>62%, 10 mg/L) in the presence of solar light. In addition, the experimental approach is inexpensive, rapid and eco-friendly for industrial scale production of nanoparticles.

Spectrophotometric and derivative spectrophotometric determination of copper (II) with dithizone in aqueous phase

A Spectrophotometric and derivative Spectrophotometric study of Cu-dithizonate complex in aqueous phase in the presence of Triton X-100, a neutral surfactant, is reported. The system obeys Beers law between 1.0 × 10−6−9.0 × 10−6 mol/l of Cu2+; detection limit is 12 ng/ml. The molar absorption coefficient, specific absorptivity and Sandells sensitivity of the complex are 3.06 × 104 1 mol−1 cm−1, 0.4825 ml g−1 cm−1 and 2.1 × 10−3 μg cm−2, respectively. The conditional stability constant of the 1 ∶ 2 complex, calculated considering simultaneously existing equilibria, has been found to be 1.73 × 1011 I2 mol2 (I = 0.07, pH 1.4, temperature = 10 °C). Absorption studies in the derivative mode have been carried out to determine the absorption maximum of the complex and to overcome interference due to the presence of certain metal ions. The method has been validated by determination of copper in beers, wines, human hair, goat liver and fly ash samples.