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Arya V.,Md University
Digest Journal of Nanomaterials and Biostructures | Year: 2010

Living organisms possess various Nature's secrets that are not completely understood by the human beings. They have inherent capacity to cope up with several types of stresses. In the present review, we emphasized on to the potential of living organisms like microbes and plants to synthesize nanoparticles not even in lab but also in their natural environment. We are highlighting the fact that biological methods of nanoparticles synthesis are more eco-friendly and safe as compared to other methods. So these can be used as factories for the production of nanoparticles and other future nanodevices. Source


An acetylcholinesterase (AChE) purified from maize seedlings was immobilized covalently onto iron oxide nanoparticles (Fe 3O 4NP) and carboxylated multi walled carbon nanotubes (c-MWCNT) modified Au electrode. An organophosphorus (OP) biosensor was fabricated using this AChE/Fe 3O 4/c-MWCNT/Au electrode as a working electrode, Ag/AgCl as standard and Pt wire as an auxiliary electrode connected through a potentiostat. The biosensor was based on inhibition of AChE by OP compounds/insecticides. The properties of nanoparticles modified electrodes were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The synergistic action of Fe 3O 4NP and c-MWCNT showed excellent electrocatalytic activity at low potential (+0.4V). The optimum working conditions for the sensor were pH 7.5, 35°C, 600μM substrate concentration and 10min for inhibition by pesticide. Under optimum conditions, the inhibition rates of OP pesticides were proportional to their concentrations in the range of 0.1-40nM, 0.1-50nM, 1-50nM and 10-100nM for malathion, chlorpyrifos, monocrotophos and endosulfan respectively. The detection limits were 0.1nM for malathion and chlorpyrifos, 1nM for monocrotophos and 10nM for endosulfan. The biosensor exhibited good sensitivity (0.475mAμM -1), reusability (more than 50 times) and stability (2 months). The sensor was suitable for trace detection of OP pesticide residues in milk and water. © 2011 Elsevier B.V. Source


Sharma V.K.,Md University | Solanki S.,Md University
Journal of Molecular Liquids | Year: 2013

The densities, ρ, speeds of sound, u of 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + aniline or N-methylaniline or 2-methylaniline (j) binary mixtures at 293.15, 298.15, 303.15, and 308.15 K and excess molar enthalpies, HE of the same mixtures at 298.15 K have been measured over entire mole fraction using DSA-5000 and 2-Drop microcalorimeter respectively. Excess molar volumes, VE and excess isentropic compressibilities, κS E values have been predicted by utilizing the measured densities and speeds of sound data. The Graph theory which deals with the topology of the constituents of mixtures has been applied to predict (i) state of components of ionic liquid mixture in their pure and mixed state; (ii) nature and extent of interactions existing in mixtures; and (iii) VE, HE and κS E values. The analysis of VE data in terms of Graph theory suggests that while 1-ethyl-3-methylimidazolium tetrafluoroborate is characterized by electrostatic forces of attraction and exists as monomer; aniline or N-methylaniline or 2-methylaniline exists as associated molecular entities. Further, (i + j) mixtures are characterized by interactions between nitrogen and fluorine atoms of 1-ethyl-3-methylimidazolium tetrafluoroborate with nitrogen and hydrogen atoms of aniline or N-methylaniline or 2-methylaniline to form 1:1 molecular complex. The IR studies also support this view point. The VE, H E and κS E values predicted by Graph theory compare well with the experimental values. © 2012 Elsevier B.V. All rights reserved. Source


Dhankhar R.,Md University | Hooda A.,Md University
Environmental Technology | Year: 2011

The removal of heavy metal from the environment, especially wastewater, is now shifting from the use of conventional methods to the use of biosorption, which may be defined as the binding and concentration of selected heavy metal ions or other molecules on to certain biological material. Although most biosorption research concerns metal and related pollutants, including radionuclides, the term is now applied for particulates and all manner of organic pollutants as well. Such pollutants can be in gaseous, soluble and insoluble forms. Biosorption is a physical process carried out through mechanisms such as ion exchange, surface complexation and precipitation. It is a property of both living and dead organisms (and their components) and has been heralded as a promising biotechnology for pollutant removal from solution. Various biomasses such as plant products (tree bark, peanut skin, sawdust, plant weeds etc.) have been tested for metal biosorption with very encouraging results. In this comprehensive review, biosorptive ability of fungal biomass toward heavy metals is emphasized. A detailed description of adsorption properties and mode of action of fungal biosorbents is offered in order to explain the heavy metal selectivity displayed by these biosorbents. The cell structure and cell wall of the fungal cell is evaluated in terms of metal sequestration. The parameters influencing the passive uptake of pollutants are analysed. The binding mechanism is discussed, including the key functional groups involved in the process. Quantification of metal-biomass interactions is fundamental to evaluation of potential implementation strategies; hence sorption isotherms and sorption kinetics, as well as models used to characterize fungal biosorbent sorption, are reviewed. Despite the continuing dramatic increase in published research on biosorption, there has been little or no exploitation in an industrial context. Thus, the current status and future directions regarding biosorption at an industrial level are discussed. A systematic comparative review of the literature, based on the metal-binding capacity of fungal biomass under different conditions, is also provided. The problems associated with fungal biosorption are analysed and suitable remedies are discussed. Thus, this article reviews the achievements and current status of fungal biosorption technology and hopes to provide insights into future research. © 2011 Taylor &Francis. Source


Devi R.,Md University | Thakur M.,Dr Sur Homeopathic College and Hospital | Pundir C.S.,Md University
Biosensors and Bioelectronics | Year: 2011

Zinc oxide nanoparticles (ZnO-NPs) were synthesized from zinc nitrate by simple and efficient method in aqueous media at 55°C without any requirement of calcinations step. A mixture of ZnO-NPs and pyrrole was eletropolymerized on Pt electrode to form a ZnO-NPs-polypyrrole (PPy) composite film. Xanthine oxidase (XOD) was immobilized onto this nanocomposite film through physiosorption. The ZnO-NPs/polypyrrole/Pt electrode was characterized by Fourier transform infrared (FTIR), cyclic voltammetry (CV), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) before and after immobilization of XOD. The XOD/ZnO-NPs-PPy/Pt electrode as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode were connected through a potentiostat to construct a xanthine biosensor. The biosensor exhibited optimum response within 5s at pH 7.0, 35°C and linearity from 0.8μM to 40μM for xanthine with a detection limit 0.8μM (S/E=3). Michaelis Menten constant (Km) for xanthine oxidase was 13.51μM and Imax 0.071μA. The biosensor measured xanthine in fish meat and lost 40% of its initial activity after its 200 uses over 100 days, when stored at 4°C. © 2011 Elsevier B.V. Source

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