Silver nanoparticles as a potential nematicide against Meloidogyne graminicola.

Plant-parasitic nematodes cause severe damage to the various agricultural crops, leading to economic losses for farmers. Therefore, identification and development of novel and environmentally benign nematicides is critically important. In this study, a silver nanoparticle (AgNP) formulation was synthesized, characterized, and investigated as a potential nematicide against rice root-knot nematode, Meloidogyne gramnicola, on rice (Oryza sativa). A series of lab assays (water and sand screening) and glasshouse experiments (using soilless system, autoclaved soil, and naturally infested soil) were conducted to examine the nematicidal effects of AgNP. The results from lab assays revealed 0.1 µg/ml as the minimum concentration for 100% irreversible nematode mortality after 12 hr in the water screening test. However, results from the sand screening test indicated 100% nematicidal effect of AgNP at 2 µg/ml after 24 hr of incubation. In glasshouse assays in soilless system of rice cultivation, 1 µg/ml concentration of AgNP applied directly to the trays achieved significant suppression of root gall formation. The effective dosage to kill nematodes in field soil assays was determined to be 3 µg/ml, which is lower than the value of 150 µg/ml reported in the literature. No visible adverse effect of AgNP was observed on seed germination or plant growth in all the experiments. The results indicate that AgNP has effective nematicidal activity against M. graminicola in rice.Plant-parasitic nematodes cause severe damage to the various agricultural crops, leading to economic losses for farmers. Therefore, identification and development of novel and environmentally benign nematicides is critically important. In this study, a silver nanoparticle (AgNP) formulation was synthesized, characterized, and investigated as a potential nematicide against rice root-knot nematode, Meloidogyne gramnicola, on rice (Oryza sativa). A series of lab assays (water and sand screening) and glasshouse experiments (using soilless system, autoclaved soil, and naturally infested soil) were conducted to examine the nematicidal effects of AgNP. The results from lab assays revealed 0.1 µg/ml as the minimum concentration for 100% irreversible nematode mortality after 12 hr in the water screening test. However, results from the sand screening test indicated 100% nematicidal effect of AgNP at 2 µg/ml after 24 hr of incubation. In glasshouse assays in soilless system of rice cultivation, 1 µg/ml concentration of AgNP applied directly to the trays achieved significant suppression of root gall formation. The effective dosage to kill nematodes in field soil assays was determined to be 3 µg/ml, which is lower than the value of 150 µg/ml reported in the literature. No visible adverse effect of AgNP was observed on seed germination or plant growth in all the experiments. The results indicate that AgNP has effective nematicidal activity against M. graminicola in rice.

High Methanol Electro-Oxidation Using PtCo/Reduced Graphene Oxide (rGO) Anode Nanocatalysts in Direct Methanol Fuel Cell.

The higher methanol utilization efficiency in direct methanol fuel cell (DMFC) is one of the key parameter to show the performance of an anode catalyst. Here in, we have synthesized a highly efficient and stable PtCo anode nanocatalysts (2-4 nm size) supported on reduced graphene oxide (rGO) for the electro-oxidation of methanol in a DMFC. Three different compositions of anode catalysts PtCo (1:7)/rGO, PtCo (1:9)/rGO and PtCo (1:11)/rGO comprising of 20% metal loading by weight of rGO are being investigated for methanol electro-oxidation in acidic medium with different methanol concentration using cyclic voltammetry. The electrochemical response from three different catalysts revealed that the PtCo (1:9)/rGO catalyst has efficiently oxidized 5 M methanol in a half cell configuration. A peak anodic current density of 46.8 mA/cm² and a power density of 136.8 mW/cm² are achieved using PtCo (1:9)/rGO anode catalyst at 100 °C for DMFC with 5 M methanol supply with negligible amount of methanol crossover. About 34% Faradaic efficiency and 22% energy efficiency is attained using PtCo (1:9)/rGO anode catalyst for a DMFC. Further, the 3% methanol oxidation reaction (MOR) efficiency is attained as revealed by evaluating the MOR by-products i.e., formic acid and formaldehyde formation. The results indicate excellent catalytic behavior of PtCo (1:9)/rGO towards MOR and its potential application as anode catalyst in DMFC.

Synthesis and Characterization of Nitrogen Doped Reduced Graphene Oxide (N-rGO) Supported PtCu Anode Catalysts for Direct Methanol Fuel Cell.

Incomplete methanol oxidation and rapid activity degradation of electro-catalysts are key barriers to successful commercialization of direct methanol fuel cell (DMFC). To address these problems, we report the synthesis of platinum-copper (PtCu) alloy nanoparticles supported on nitrogen doped reduced graphene oxide (N-rGO) as the anode catalyst for the efficient electro-oxidation of methanol. Catalysts with varying molar ratios of PtCu were fabricated using impregnation reduction method and their electrochemical performance was compared with the commercially available Pt/C (20 wt%) anode catalyst. The electro-catalytic activity of the synthesized PtCu (1:2)/N-rGO catalyst was found to be much higher to those that observed for Pt/N-rGO and Pt/C catalyst as revealed by cyclic voltammetry, electrochemical impedance spectroscopy and electron transfer measurements. The enhanced electrochemical activity of PtCu (1:2)/N-rGO catalyst is not only attributed to strong interfacial interaction between the nitrogen group of N-rGO and PtCu active metal phase but also to the altered electronic structure of Pt as a result of Cu alloying. This reduces the adsorption of CO and OH- species on Pt surface, thereby creating more Pt active sites for methanol electro-oxidation; thus faster kinetics is exhibited. These results indicate the potential application of PtCu/N-rGO catalyst as an anode material in a DMFC.

Synthesis and Characterization of PtCo Alloy Nanoparticles Supported on a Reduced Graphene Oxide/g-C3N4 Composite for Efficient Methanol Electro-Oxidation.

In the development of direct methanol fuel cell (DMFC) the fabrication of an anode comprising of a Pt or Pt-based bi or tri-metallic alloys nanoparticles on a suitable support material having higher stability, higher surface area, electrical conductivity and strong interaction is very important. In the present work we have solved this problem by using a nanocomposite of reduced graphene oxide (rGO) and graphitic carbon nitride (g-C3N4) as the support material and deposited PtCo nanoparticles by in-situ chemical reduction. The electro-oxidation of methanol is carried out in an acidic medium. The electrochemical behaviour of as-synthesized PtCo/rGO-gC3N4 catalyst was found to be much superior to Pt/rGO-g-C3N4 catalysts towards electro-oxidation of methanol and is mainly due to the homogeneous dispersion of PtCo nanoparticles onto rGO-g-C3N4 nano composite, higher electrical conductivity and a strong interaction between metal nanoparticles and N group of the support material. By using the as-synthesized electro-catalyst the adsorption or poisoning of Pt due to CO is greatly reduced and more active Pt sites are created for the electro-oxidation of methanol. Thus, the as-synthesized electro-catalyst can be used as an efficient anode material in a direct methanol fuel cell.

In vitro cytotoxicity of GO-DOx on FaDu squamous carcinoma cell lines.

We have synthesized graphene oxide (GO) nanosheets using modified Hummer's method and conjugated it with doxorubicin (DOx), an anticancer drug. Drug release kinetics from GO-DOx conjugate indicated the drug release at acidic pH. MTT assay performed on FaDu hypopharyngeal cancer cell lines revealed that the GO-DOx nanoconjugate inhibited cell proliferation more efficiently compared with pure DOx. Preliminary results indicate the potential of designed GO-DOx drug conjugate for head and neck cancer.

Synthesis and characterization of multifunctional gold nanoclusters for application in radiation therapy.

Gold nanoparticles, because of their high radiation absorption coefficient and efficient generation of secondary photoelectrons, have been predicted to enhance therapeutic efficacy in radiation therapy. However, high dose for effective treatment limits their use. We have synthesized multifunctional gold nanoclusters (GNCs) that can be used for imaging and radiation therapy. The designed GNCs have been characterized for their physicochemical properties, biocompatibility, and their radiation dose enhancement potential on PC3 cell lines.