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ABSTRACT: A novel Co(3)O(4) nanoparticles-decorated graphene (GR) composite was synthesized by electro-deposition and characterized by scanning electron micrographs, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. Then, amperometric biosensors based on a Co(3)O(4) nanoparticles-decorated GR composite modified glassy carbon electrode (GCE) were developed for the sensitive determination of L-tryptophan (Trp). The direct electrooxidation behaviors of Trp on the Co(3)O(4)/GR/Nafion/GCE were carefully investigated by cyclic voltammetry and square wave voltammetry. The results indicated that Trp showed an increase of the oxidation peak current with a negative shift of the oxidation peak potential compared with that on the bare GCE. Under optimum conditions, the proposed biosensor can be applied to the quantification analysis of Trp with a wide linear range covering 0.05-10 μM (R = 0.996) and a low detection limit of 0.01 μM. The experimental results also showed that the sensor exhibited good reproducibility, long-term stability as well as high selectivity. Moreover, the novel biosensor for the detection of Trp in a real amino acid sample with satisfactory results has been proved.
The Analyst 05/2012; 137(12):2840-5. · 4.23 Impact Factor
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ABSTRACT: A reliable and simple sensor was fabricated by modifying a carbon paste electrode with nanosized gold particles and poly (glutamic
acid) for determination of paracetamol (PAR). The modified electrode exhibited an effective catalytic response to the oxidation
and reduction of PAR with good reproducibility and stability. The determination was carried out by differential pulse adsorptive
stripping voltammetry after a 30s accumulation time with an open circuit potential and under stirring. The calibration curve
is linear in the range from 0.05 to 70μM of PAR (with a correlation coefficient of 0.9990), and the sensitivity is 1.51μA·μM-1. The modified electrode was used to detect PAR in commercial tablets.
KeywordsCarbon paste electrode-Glutamic acid-Nanogold-Paracetamol-Adsorptive stripping voltammetry
Microchimica Acta 04/2012; 171(1):133-138. · 3.03 Impact Factor
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ABSTRACT: A novel nitrite sensor was fabricated based on a graphene/polypyrrole/chitosan nanocomposite film modified glassy carbon electrode. The nanocomposite film was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The electron transfer behaviour of the modified electrodes was investigated in [Fe(CN)(6)](3-)/(4-) redox probe using cyclic voltammetry and electrochemical impedance spectroscopy. Differential pulse voltammetry and amperometry were used to study the electrochemical properties of the proposed sensor. Under optimum conditions, the sensor exhibited good reproducibility and stability for nitrite determination. Linear response was obtained in the range of 0.5-722 μM with a detection limit of 0.1 μM (S/N = 3) for nitrite determination.
The Analyst 09/2011; 136(21):4563-9. · 4.23 Impact Factor
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ABSTRACT: A novel poly-glutamic acid (PGA) film modified carbon paste electrode (CPE) incorporating carbon nanotubes (CNTs) was first prepared for the determination of l-tryptophan (l-Trp). Scanning electron microscopy and Fourier transform infrared spectroscopy were applied for characterization of the surface morphology of the modified electrodes and cyclic voltammetry was used to investigate the electrochemical properties of the proposed electrode towards the oxidation of l-Trp. Optimization of the experimental parameters was performed with regard to pH, ratio of CNTs, concentration of glutamic acid, electro-polymerization cycles, accumulation time and concentration of sodium dodecylbenzene sulfonate. The linearity between the oxidation peak current and the l-Trp concentration was obtained in the range of 5.0×10(-8) to 1.0×10(-4)M with a detection limit of 1.0×10(-8)M (S/N=3) and the sensitivity was calculated to be 1143.79μA∙mM(-1)∙cm(-2). In addition, the PGA modified CPE incorporating CNTs displayed high selectivity, good stability and reproducibility, making it suitable for the routine analysis of l-Trp in clinical use.
Bioelectrochemistry (Amsterdam, Netherlands) 05/2011; 82(1):38-45. · 2.65 Impact Factor
