| 1. |
- Ghosh, Tanushree, et al.
(författare)
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A novel third generation uric acid biosensor using uricase electro-activated with ferrocene on a Nafion coated glassy carbon electrode
- 2015
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Ingår i: Bioelectrochemistry. - : Elsevier. - 1567-5394 .- 1878-562X. ; 102
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Tidskriftsartikel (refereegranskat)abstract
- A new uric acid biosensor was constructed using ferrocene (Fc) induced electro-activated uricase (UOx) deposited within Nation (Naf) on glassy carbon electrode (GCE). Electro-activation of UOx was successfully achieved by cyclic voltammetry through the electrostatic interaction of Fc with Trp residues within the hydrophobic pockets in UOx. The Naf/UOx/Fc composite was characterised by AFM, FTIR and EDX to ensure proper immobilisation. The interaction of Fc with the enzyme was analysed by Trp fluorescence spectroscopy and the alpha-helicity of the protein was measured by CD spectropolarimetry. The charge transfer resistance (R-ct), calculated from electrochemical impedance spectroscopy, for the modified sensor was lowered (1.39 k Omega) and the enzyme efficiency was enhanced by more than two fold as a result of Fc incorporation. Cyclic voltammetty, differential pulse voltammetty and amperometry all demonstrated the excellent response of the Naf/UOx/Fc/GCE biosensor to uric acid. The sensor system generated a linear response over a range of 500 nM to 600 mu M UA, with a sensitivity and limit of detection of 1.78 mu A mu M-1 and 230 nM, respectively. The heterogeneous rate constant (k(s)) for UA oxidation was much higher for Naf/UOx/Fc/GCE (1.0 x 10(-4) cm s(-1)) than for Naf/UOx/GCE (8.2 x 10(-5) cm s(-1)). Real samples, i.e. human blood, were tested for serum UA and the sensor yielded accurate results at a 95% confidence limit. (C) 2014 Elsevier B.V. All rights reserved.
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| 2. |
- Ghosh, Tanushree, et al.
(författare)
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Disposable uric acid biosensor by bacterial crude uricase enzyme modified screen printed electrode
- 2015
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Ingår i: Journal of the Indian Chemical Society. - : SCIENTIFIC PUBL-INDIA. - 0019-4522. ; 92:1, s. 127-133
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Tidskriftsartikel (refereegranskat)abstract
- Uric acid is the primary end product from purine derivatives in human metabolism. Excessive production of uric acid may lead to gout, hyperuricemia and kidney disorder: Different analytical methods for uric acid such as Colorimetry, commercial enzyme electrode and commercially available uric acid kit are used widely. The main purpose of this research was to develop,a screen printed electrode based uric acid biosensor using gelatin immobilized uricase enzyme extracted from Comamonas sp. BTUA. The enzyme catalyzed oxidation of uric acid in presence of oxygen, producing allantoin and hydrogen peroxide. The linearity of the standard curve in the concentration ranges from 5.94 x 10(-6) to 4.75 x 10(-4) molar was satisfactory and could be used for the quantitative determination of uric acid in human serum samples. The limit of detection (LOD) was 2.26 mu M and sensitivity was evaluated as 3.31 nA mu M-1 of uric acid. One Modified electrode could be used for six measurements with 95%. accuracy up to 25 days. The developed biosensor was easy to use, inexpensive, sensitive and reliable.
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| 3. |
- Wiel, Clotilde, 1987, et al.
(författare)
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BACH1 Stabilization by Antioxidants Stimulates Lung Cancer Metastasis
- 2019
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Ingår i: Cell. - : Elsevier BV. - 0092-8674 .- 1097-4172. ; 178:2, s. 330-345
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Tidskriftsartikel (refereegranskat)abstract
- For tumors to progress efficiently, cancer cells must overcome barriers of oxidative stress. Although dietary antioxidant supplementation or activation of endogenous antioxidants by NRF2 reduces oxidative stress and promotes early lung tumor progression, little is known about its effect on lung cancer metastasis. Here, we show that long-term supplementation with the antioxidants N-acetylcysteine and vitamin E promotes KRAS-driven lung cancer metastasis. The antioxidants stimulate metastasis by reducing levels of free heme and stabilizing the transcription factor BACH1. BACH1 activates transcription of Hexokinase 2 and Gapdh and increases glucose uptake, glycolysis rates, and lactate secretion, thereby stimulating glycolysis-dependent metastasis of mouse and human lung cancer cells. Targeting BACH1 normalized glycolysis and prevented antioxidant-induced metastasis, while increasing endogenous BACH1 expression stimulated glycolysis and promoted metastasis, also in the absence of antioxidants. We conclude that BACH1 stimulates glycolysis-dependent lung cancer metastasis and that BACH1 is activated under conditions of reduced oxidative stress.
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