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A study of the antioxidative behavior of phenolic acids, in aqueous herb extracts, using a dsDNA biosensor

100%
Skeva E., Girousi S.
Open Chemistry
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2012
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vol. 10
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issue 4
1280-1289
EN
Electrochemical DNA biosensors are promising tools for the fast, inexpensive and simple in vitro analysis for the determination of free radicals and antioxidants. High concentrations of antioxidants in such compounds as phenolic acids and plant extracts, act as free radical terminators which reduce the effect of the oxidative dam-age on DNA. The electrochemical behavior of three representative phenolic acids, caffeic acid, gallic acid and trolox were studied by cyclic voltammetry. Moreover, the determination of the above antioxidants under the optimized conditions (scan rate, deposition potential and time) using differential pulse voltammetry was also investigated. In vitro studies focused on their antioxidative effect were performed by adsorptive transfer stripping voltammetry and dsDNA biosensor. Using Fenton’s system, with FeSO4 and H2O2 was chosen as a strong oxidative system. This biosensor was applied as a screening antioxidant test in order to estimate the antioxidant capacity of aqueous herb extracts. [...]
2
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Electrochemical study of dsDNA on carbon nanotubes paste electrodes applying cyclic and differential pulse voltammetry

81%
Serpi C., Voulgaropoulos A., Girousi S.
Open Chemistry
|
2013
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vol. 11
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issue 3
413-423
EN
Abstract Carbon nanotubes paste electrodes (CNTPEs) in combination with adsorptive transfer stripping voltammetry are shown to be very suitable for the determination of calf thymus double-stranded DNA (dsDNA). The performance of three types of multi-walled carbon nanotubes paste electrodes (MWCNTPEs) is investigated. The effects of surface pre-treatment and accumulation conditions on the adsorption and electrooxidation of the dsDNA at MWCNTPEs are also described. The results indicate that the electroactivity inherent to carbon nanotubes/paste electrodes allows a large enhancement of the guanine oxidation signal compared to that obtained at the conventional carbon paste electrodes (CPEs). Moreover, the extent of the enhancement dependents on the type of MWCNTs incorporated into the paste. Based on the signal of guanine, under optimal conditions, very low levels of dsDNA can be detected following short accumulation times for all three types of MWCNTPEs (MWCNTPE1, MWCNTPE2, MWCNTPE3), with detection limits of 2.64 mg L−1, 2.02 mg L−1 and 1.46 mg L−1, respectively. Additionally, the dsDNA isolated from rat liver tissues is determined by use of the previously mentioned MWCNTPEs. Graphical abstract [...]
3
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Square wave anodic stripping voltammetry determination of eco-toxic metals in samples of biological and environmental importance

81%
Anastasiadou Z., Jannakoudakis P., Girousi S.
Open Chemistry
|
2010
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vol. 8
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issue 5
999-1008
EN
Square wave anodic stripping voltammetry was used in simultaneous determinations of eco-toxic metals (Pb, Cd, Cu and Zn) on bismuth film electrodes. The electrodes were prepared in situ on a glassy-carbon electrode (GCE) from 0.1 M acetate buffer (pH 4.5) containing 200 μg L−1 of bismuth (III), as well ex situ on electrochemically oxidized graphitized polyacrylonitrile carbon fibres from 200 mg L−1 Bi(NO3)3 in 1% HNO3 (aqueous) solution. Preparation of a Bi-modified carbon fibre electrode (CFE) was by cation exchange of Bi+3 ions for H+ of the acidic surface groups of the electro-oxidized carbon fibres, followed by electrochemical reduction to Bi0. For the Bi-GCE the linear range was 20–280 μg L−1 for zinc, 10–100 μg L−1 for lead, 10–80 μg L−1 for copper, and 5–50 μg L−1 for cadmium. For the Bi-CFE it was 20–160 μg L−1 for zinc, 10–100 μg L−1 for lead, 10–100 μg L−1 for copper, and 2–120 μg L−1 for cadmium. For both kinds of bismuth modified carbon electrodes, low limits of detection and satisfactory precision were achieved. The method was successfully applied to certified reference materials of biological (bovine liver) and environmental (mussel tissue) importance. [...]
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