Zia Ur Rahman

Lanzhou University, Lanzhou, Gansu Sheng, China

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Publications (9)26.13 Total impact

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    ABSTRACT: MFe2O4 (M=Mg, Ni, Cu) magnetic nanoparticles (MNPs) were found to have catalytic activities similar to those of biological enzymes such as catalase and peroxidase. These nanomaterials, as bifunctional catalase/peroxidases (KatGs), not only could catalyze H2O2 to produce hydroxyl radicals, which oxidized peroxidase substrate to produce color, but also could catalyze the decomposition reaction of H2O2 into water and oxygen directly in the same condition through the catalase-like activity. And it was also found that the amount of generated hydroxyl radicals and oxygen was related to the concentration of MFe2O4 (M=Mg, Ni, Cu) MNPs. The peroxidase-like catalytic behavior of MFe2O4 MNPs was analyzed in detail. Under the optimized conditions, NiFe2O4 MNPs were used as a colorimetric biosensor for the detection of 9.4×10(-7)-2.5×10(-5)molL(-1) glucose with a limit of detection (LOD) of 4.5×10(-7)molL(-1). The sensor was successfully applied to glucose detection in urine sample.
    Biosensors and Bioelectronics. 01/2015; 63:384–391.
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    ABSTRACT: In this study, an on-line sample preconcentration technique, field-amplified sample injection combined with water removal by electroosmotic flow pump, was applied to realize a highly sensitive chiral analysis of β-blocker enantiomers by microemulsion electrokinetic chromatography (MEEKC). The introduction of a water plug in capillary before the electrokinetic injection provided the effective preconcentration of chiral compounds. And then the water was moving out of the column from the injection end under the effect of the electroosmotic flow (EOF), which avoided dilution of the stacked β-blocker enantiomers concentration suffering from the presence of water in separation buffer. Moreover, the addition of H3PO4 and methanol in the sample solution greatly improved the enhancement efficiency further. Under optimized conditions, more than 2700-fold enhancement in sensitivity was obtained for each enantiomer of bupranolol (BU), alprenolol (AL) and propranolol (PRO) via electrokinetic injection. Limits of detection were 0.10, 0.10, 0.12, 0.11, 0.02 and 0.02 ng/mL for S-BU, R-BU, S-AL, R-AL, S-PRO and R-PRO, respectively. Eventually, the proposed method was successfully applied to the determination of BU, AL and PRO in serum samples with good recoveries ranging from 93.4 to 98.2%.This article is protected by copyright. All rights reserved
    Electrophoresis 05/2014; · 3.26 Impact Factor
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    ABSTRACT: Due to the unusual properties of the structure, the metal organic frameworks (MOFs) have received great interest in separation science. However, the most existing methods for the applications of MOFs in separation science require an off-line procedure to prepare the materials. Here, we report an in situ, layer-by-layer self-assembly approach to fabricate MIL-100(Fe) coated open tubular (OT) capillary columns for capillary electrochromatography. By a controllable manner, the OT capillary columns with a tailored MIL-100(Fe) coating have been successfully synthesized. The results of SEM, XRD, FT-IR, and ICP-AES indicated that MIL-100(Fe) was successfully grafted on the inner wall of the capillary. Some neutral, acidic and basic analytes were used to evaluate the performance of the MIL-100(Fe) coating OT capillary column. Because of the size selectivity of lattice aperture and hydrophobicity of the organic ligands, three types of analytes were well separated with this novel MIL-100(Fe) coating OT capillary column. For three consecutive runs, the intra-day relative standard deviations (RSDs) of migration time and peak areas were 0.4-4.6% and 1.2-6.6%, respectively. The inter-day RSDs of migration time and peak areas were 0.6-8.0% and 2.2-9.5%, respectively. The column-to-column reproducibility of retention time was in range of 0.6-9.2%. Additionally, the 10 cycles OT capillary column (10-LC) could be used for more than 150 runs with no observable changes on the separation efficiency.
    Analytical Chemistry 11/2013; · 5.70 Impact Factor
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    ABSTRACT: In this paper, we established a new on-line method using micelle to solvent stacking (MSS) technique combining with large amount sample electrokinetic stacking injection (LASEKSI) for the analysis of cationic molecules. In this MSS-LASEKSI, by modulating the integral EOF across the capillary, a equilibrium state was formed and can be maintained for a long time, leading to the continuous stacking of the analytes on the basis of MSS. Thereby, an extremely large amount sample was permitted to be injected into the capillary and then an improved enrichment fold can be achieved comparing with the each case. The variables affecting the performance of MSS-LASEKSI were investigated and discussed. Under the optimized conditions, 6.3×10(3)- and 6.4×10(2)-fold enrichment in peak heights upon normal CZE method (injected at 0.5psi for 3s) and number of plates of 2.9×10(6) and 6.5×10(5) were attained for berberine and theophylline, respectively. The developed method described here may provide prospects for exploiting a new concentration technique to achieve higher enrichment factor.
    Journal of Chromatography A 09/2012; · 4.61 Impact Factor
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    ABSTRACT: In this report, graphene oxide-Fe(3)O(4) magnetic nanocomposites were demonstrated to possess intrinsic peroxidase-like activity and enhanced affinity toward H(2)O(2). The nanocomposites retain their magnetic properties and can be effectively separated by a magnet. Significantly, they were proved to be novel peroxidase mimetics which could quickly catalyze oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H(2)O(2), producing a blue-colored solution. Kinetic analysis indicates that the catalytic behavior is in accord with typical Michaelis-Menten kinetics and follows a ping-pong mechanism. On the basis of the high activity, the reaction provides a simple, sensitive and selective method for colorimetric detection of glucose in diabetic urine.
    Nanoscale 05/2012; 4(13):3969-76. · 6.73 Impact Factor
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    ABSTRACT: Magnetic iron oxide nanoparticles were prepared by chemical co-precipitation method and then modified with sodium citrate. These iron oxide nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), and vibrating sample magnetometer (VSM). BSA was adsorbed on these citrate modified nanoparticles using two types of buffers (acetate buffer, pH 4.0, 4.7 and phosphate buffer, pH 7.4). The results showed that the maximum adsorption of BSA was 83 mg/g at its isoelectric point (pH 4.7). Fourier-transform infrared spectroscopy (FTIR) was used to confirm the attachment of citrate groups and BSA on the prepared magnetic nanoparticles. BSA was desorbed from nanoparticles under alkaline conditions, which was confirmed by SDS-PAGE electrophoresis, UV-vis and fluorescence spectra. The desorbed BSA showed small changes in its structure. The adsorption results indicated that BSA adsorption on citrate modified iron oxide nanoparticles occurred mainly by electrostatic mechanism.
    Journal of Nanoscience and Nanotechnology 03/2012; 12(3):2598-606. · 1.15 Impact Factor
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    ABSTRACT: In this study, the interaction between C.I. Acid Orange 7 (AO7) and human serum albumin (HSA) was firstly investigated using nuclear magnetic resonance (NMR) spectroscopy in combination with fluorescence quenching spectroscopy, three-dimensional fluorescence spectroscopy, UV–vis absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy and molecular modeling method in vitro. The results of NMR data confirmed that AO7 indeed interacted with HSA, and the hydrophobic portion of AO7 should be embedded to the hydrophobic pocket of HSA. The fluorescence quenching analysis revealed that AO7 can bind to HSA. The conformational change of HSA in the presence of AO7 was confirmed by synchronous fluorescence, three-dimensional fluorescence, UV–vis absorption, FT-IR and CD spectra. The binding distance between AO7 and tryptophan residue of HSA was calculated by the efficiency of fluorescence resonance energy transfer. Molecular modeling showed that hydrophobic force and hydrogen bonds were the major interaction between AO7 and HSA.
    Dyes and Pigments 03/2012; 92(3):1100–1107. · 3.53 Impact Factor
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    ABSTRACT: Guanidine group (Gnd) functionalized magnetic nanoparticles (Fe3O4@SiO2@NH2-Gnd) were synthesized and characterized in this work for the first time. The characterization of Fe3O4@SiO2@ NH2-Gnd nanoparticles was demonstrated by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectra, vibration sample magnetometer, and zeta potential analyzer. The novel multifunctional nanoparticles were served as a solid-phase extraction sorbent for easy isolation and preconcentration of acidic protein from aqueous solution only using a magnet. Bovine serum albumin (BSA) was selected as a model protein and the main experimental parameters influencing the adsorption and desorption efficiency were investigated and optimized. Under the optimum conditions, the particles reached saturated adsorption within 20 min and exhibited significant specific recognition for the acidic proteins. Fifteen fold enrichment efficiency was achieved and the detection limits was 45 ng x mL(-1) for BSA by capillary electrophoresis (CE). The practical application of the novel nanoparticles as a sorbent for the isolation and preconcentration of acidic proteins from basic proteins was demonstrated by effective separation and enrichment of bovine serum albumin from lysozyme and cytochrome C mixture, which was assayed by CE.
    Journal of Nanoscience and Nanotechnology 12/2011; 11(12):10387-95. · 1.15 Impact Factor
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    ABSTRACT: Multifunctional nanocomposites with mesoporous silica having superparamagnetic, near-infrared (NIR) plasmon resonance, and catalytic behavior, were synthesized. These nanocomposites, with an inner magnetite core, an outer mesoporous silica shell, and a gold shell sandwiched between a thin silica layer and a thick outer silica shell, were characterized using different techniques, such as transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy, vibrating sample magnetometer, UV–vis spectroscopy, X-ray photoelectron spectrometry, dynamic light scattering, zeta potential, N2 adsorption/desorption, and thermal gravimetric analysis. The results indicated that the nanocomposites have high magnetization (21.4 emu/g) due to the inner magnetite core, significant absorbance in the NIR region due to the gold shell, large surface area (315 m2/g), and mesopores (2.1 nm) in the outer silica shell. The outer mesoporous silica shell was investigated for adsorption and release of drug as well as for attaching of dye molecules, while the gold shell was investigated its catalytic behavior. These multifunctional nanocomposites show adsorption and sustained release of ibuprofen, and also have excellent catalytic behavior.
    Chemical Engineering Journal. 222:382–390.