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Andhariya N.,Bhavnagar University | Chudasama B.,Thapar University | Mehta R.V.,Bhavnagar University | Upadhyay R.V.,Charotar University of Science & Technology
Journal of Nanoparticle Research | Year: 2011

The use of nanoparticles as drug delivery systems for anticancer therapeutics has great potential to revolutionize the future of cancer therapy. The aim of this study is to construct a novel drug delivery platform comprising a magnetic core and biodegradable thermoresponsive shell of tri-block-copolymer. Oleic acid-coated Fe3O4 nanoparticles and hydrophilic anticancer drug "doxorubicin" are encapsulated with PEO-PLGA-PEO (polyethylene oxide-poly d, l lactide-co-glycolide-polyethylene oxide) tri-block-copolymer. Structural, magnetic, and physical properties of Fe 3O4 core are determined by X-ray diffraction, vibrating sample magnetometer, and transmission electron microscopy techniques, respectively. The hydrodynamic size of composite nanoparticles is determined by dynamic light scattering and is found to be ∼36.4 nm at 25°C. The functionalization of magnetic core with various polymeric chain molecules and their weight proportions are determined by Fourier transform infrared spectroscopy and thermogravimetric analysis, respectively. Encapsulation of doxorubicin into the polymeric magnetic nanoparticles, its loading efficiency, and kinetics of drug release are investigated by UV-vis spectroscopy. The loading efficiency of drug is 89% with a rapid release for the initial 7 h followed by the sustained release over a period of 36 h. The release of drug is envisaged to occur in response to the physiological temperature by deswelling of thermoresponsive PEO-PLGA-PEO block-copolymer. This study demonstrates that temperature can be exploited successfully as an external parameter to control the release of drug. © 2010 Springer Science+Business Media B.V.

Parekh K.,k-Technology | Upadhyay R.V.,Charotar University of Science & Technology
Journal of Magnetic Resonance | Year: 2012

The electron spin resonance (ESR) technique has been applied to study the spin dynamics in broad temperature range for rare earth doped Mn 0.5Zn0.5Fe1.9Gd0.1O4 (MZG5) magnetic fluid. Zero field cooled (ZFC) ESR spectra of MZG5 fluid exhibit an isotropic shift in the resonance field below 40 K, while the field cooled (FC) ESR spectra show a deviation from sin2 θ behavior and an angle dependent hysteresis, this unambiguously points to the dominating unidirectional freezing of surface spins below 40 K. Above 60 K, the resonance field exhibits sin2 θ behavior, indicating the uniaxial anisotropy contribution of core spin. This indicates that surface spin freezing temperature is around 40 K. The presence of surface spin freezing and the coupling between core and surface spins are further supported by cycle dependent FC ESR spectra measured at 20 K, which show the systematic increase in resonance field (Hres) and intensity. The double peak behavior of blocking temperature distribution retrieved from ZFC-FC magnetization measurement is an additional corroboration of the existence of surface spin glass like layer. © 2012 Elsevier Inc. All rights reserved.

Popli S.,Charotar University of Science & Technology | Patel U.D.,M. S. University of Baroda
International Journal of Environmental Science and Technology | Year: 2012

Dyes are synthetic organic compounds widely used in various industries such as, textile, leather, plastic, food, pharmaceutical, and paints manufacturing industries. Coloured effluents are highly toxic to the aquatic life and mutagenic to humans. Wastewater containing dyes has become an important issue demanding serious attention. Among the synthetic dyes, azo dyes are the largest and most widely used dyes and account for more than half of the annually produced dyes. The biodegradation of azo dyes is difficult due to their complex structure and synthetic nature. Several treatments have been proposed for efficient azo dye removal, most of them presenting some limitations such as generation of waste sludge, high operational costs, poor efficiency, and incomplete mineralization. Biological treatment is a cost-effective and eco-friendly process for dye degradation. Sequential anaerobic–aerobic biological treatment is considered as one of the most cost-effective methods for the complete mineralization of azo dyes. The anaerobic stage yields decolourization through reductive cleavage of the dye’s azo linkages, resulting in the formation of generally colourless but potentially hazardous aromatic amines. The aerobic stage involves degradation of the aromatic amines. It is the most logical step for removing the azo dyes from the wastewater. Several factors can influence the microbial activity and consequently the efficacy and effectiveness of the complete biodegradation processes. This paper summarizes the results of biological decolourization of azo dyes using various types of reactors, elaborates biochemical mechanisms involved, and discusses influence of various operational parameters on decolourization based on reports published in the last decade. © 2014, Islamic Azad University (IAU).

Chudasama B.,Thapar University | Vala A.K.,Bhavnagar University | Andhariya N.,Bhavnagar University | Mehta R.V.,Bhavnagar University | Upadhyay R.V.,Charotar University of Science & Technology
Journal of Nanoparticle Research | Year: 2010

In this article, we describe a simple onepot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO3 using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block copolymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV- vis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 ± 1.5 nm (σ= 18.3%) and 31.1 ± 4.5 nm (σ= 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive (Bacillus megaterium and Staphylococcus aureus), and three Gram negative (Escherichia coli, Proteus vulgaris and Shigella sonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.

Parekh K.,Indian Institute of Technology Gandhinagar | Upadhyay R.V.,Charotar University of Science & Technology
Journal of Applied Physics | Year: 2010

Static and dynamic magnetic properties of oleic acid/oleyamine coated Mn-Zn ferrite nanoparticles of diameter 82 Å are reported. The zero-field-cooled peak temperature decreases with increasing magnetic field and obeys the well known de Almeida-Thouless line. The zero-field-cooled magnetization data are simulated by assuming noninteracting magnetic particles with uniaxial anisotropy and lognormal particle size distribution. The relevant parameters give the values of particle diameter (D) 80 Å, standard deviation 0.3 in ln(D), and the anisotropy constant K to be 5.8× 10 5 erg/cm3. The observed higher value of standard deviation is due to the interparticle interaction. The complex magnetic susceptibility was measured as a function of temperature for frequencies ranging from 67 to 1800 Hz. The temperature at which the maximum in the ac-susceptibility curve is observed is well accounted by the Vogel-Fulcher law for both χ′ and χ″. The peak is also observed in a plot of χ″/χ′ versus temperature, which may mean the existence of magnetic aftereffect, and furthermore, it has an Arrhenius as well as Vogel-Fulcher law type dependence. An observed nonthermal activation type relaxation mechanism at 12 K is attributed to possible quantum tunneling effect in Mn-Zn ferrite nanoparticles. © 2010 American Institute of Physics.

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