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ABSTRACT: A novel biosensor was developed based on tyrosinase immobilization with ordered mesoporous carbon-Au (OMC-Au), l-lysine membrane and Au nanoparticles on a glassy carbon electrode (GCE). It was applied for the simultaneous determination of dihydroxybenzene isomers using differential pulse voltammetry (DPV). The tyrosinase/OMC-Au/l-lysine/Au film was characterized by scanning electron microscopy (SEM) and impedance spectra. Under optimized conditions, the DPV study results for two isomers, hydroquinone (HQ, 1,4-dihydroxybenzene) and catechol (CC, 1,2-dihydroxybenzene) showed low peak potentials, and the peak-to-peak difference was about 135.85 mV, which ensured the anti-interference ability of the biosensor and made simultaneous detection of dihydroxybenzene isomers possible in real samples. DPV peak currents increased linearly with concentration over the range of 4.0 × 10(-7) to 8.0 × 10(-5) M, and the detection limits of hydroquinone and catechol were 5 × 10(-8) M and 2.5 × 10(-8) M (S/N = 3), respectively. The tyrosinase biosensor exhibited good repeatability and stability. In addition, the response mechanism of enzyme catalysed redox on the OMC-Au/l-lysine/Au film modified electrode based on electrochemical study was discussed. The proposed method could be extended for the development of other enzyme-based biosensors.
The Analyst 05/2013; · 4.23 Impact Factor
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ABSTRACT: We have developed an optical assay for NADH (Dihydronicotinamide adenine dinucleotide) based on the catalytic growth of gold-silver core-shell nanoparticles (Au-Ag-CSNPs). The nanoparticles were immobilized on pretreated glass slide and are shown to catalyze the NADH-mediated reduction of Ag(I) ions in the presence of 1,4-benzoquinone and cetyltrimethyl ammonium ion. This leads to the formation of Au-Ag-CSNPs on the glass. The absorption peak of the Au-Ag-CSNPs at 415nm increases with the concentration of NADH in the solution used, and this can be measured by UV-vis photometry. High-resolution scanning electron microscopy analysis of the morphology of the surface of the Au-Ag-CSNPs before and after the catalytic reaction revealed a growth of their diameter. Under optimal conditions, NADH can be determined in the concentration range from 0.2 to 3.2mM, and the detection limit is 15.6μM. The sensor has good precision and good storage stability, simple in operation, and can be fabricated at low costs, which made it suitable for the determination of NADH in complex biological systems and in related degradation processes of contaminants.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 09/2012; · 2.10 Impact Factor
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Yuanyuan Liu,
Zhuotong Zeng,
Guangming Zeng,
Lin Tang,
Ya Pang,
Zhen Li,
Can Liu, Xiaoxia Lei,
Mengshi Wu,
Pinyun Ren,
Zhifeng Liu,
Ming Chen,
Gengxin Xie
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ABSTRACT: A novel magnetically separable laccase immobilized system was constructed by adsorbing laccase into bimodal carbon-based mesoporous magnetic composites (CMMC). A large adsorption capacity (491.7 mg g(-1)), excellent activity recovery (91.0%) and broader pH and temperature profiles than free laccase have been exhibited by the immobilized laccase. Thermal stability was enhanced to a great extent and operational stability was increased to a certain extent. The shift of kinetic parameters indicated affinity change between enzyme and substrate. Application of the immobilized system in phenol and p-chlorophenol removal was investigated in a batch system. Adsorption effects of the support were responsible for the quick removal rate in the first hour, and up to 78% and 84% of phenol and p-chlorophenol were removed in the end of the reaction, respectively, indicating that the magnetic bimodal mesoporous carbon is a promising carrier for both immobilization of laccase and further application in phenol removal.
Bioresource technology 11/2011; 115:21-6. · 4.25 Impact Factor
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ABSTRACT: a b s t r a c t A stable magnetic nanoparticle with a shell core structure of -Fe 2 O 3 @Fe 3 O 4 was developed. Water soluble Polyethylenimine (PEI) was grafted to the nanoparticle to prepare a positive charged adsorbent, which was characterized by XRD, FTIR and SEM. The adsorbent was able to effectively remove anionic Cr(VI) in the pH range of 2–3 due to the large amount of protonated imine groups on its surface, and could be magnetically separated from liquid quickly. Adsorption equilibrium was reached within 30 min and independent of initial Cr(VI) concentration. The Cr(VI) maximum sorption capacity at a temperature range of 35–15 • C was obtained using the Langmuir adsorption isotherm. The calculated thermodynamic parameters (G, H, and S) indicated that adsorption of Cr(VI) was spontaneous and exothermic in nature. Competition from coexisting ions (K + , Na + , Ca 2+ , Cu 2+ , Cl − , and NO 3 −) was found insignificant. The adsorbent had satisfying acid–alkali stability and could be regenerated by 0.02 mol L −1 NaOH solution. The results suggested the potential application of the PEI-modified magnetic nanoparticles in selective removal of Cr(VI) from wastewater.
Chemical Engineering Journal. 01/2011; 175:222-227.
