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Electrochemical Fabrication of Carbon Nanomaterial and Conducting Polymer Composites for Chemical Sensing
Published in Di Wei, Electrochemical Nanofabrication, 2017
Zhanna A. Boeva, Rose-Marie Latonen, Tom Lindfors, Zekra Mousavi
Recently, an oxalate biosensor based on the composite of graphite oxide, PPy, PANI and chitosan was reported by Devi et al. [109]. PPy was first deposited electrochemically together with graphite oxide on a Au electrode. Aniline was then electrochemically polymerized in the presence of chitosan on the PPy and graphite oxide composite. Eventually, oxalate oxidase was covalently immobilized on the composite film surface via the amino groups of chitosan by using glutaraldehyde chemistry. The composite biosensor was used for amperometric detection of oxalate both in buffer solution and in human serum. It was found to be selective to oxalate in the presence of glucose, UA, AA, cysteine, acetic acid, ethanol, and citric acid and showed a linear response range from 1 to 400 μM. The biosensor has potential application areas within diagnostics of acute and chronic kidney diseases.
Analytical Chemistry
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Results/Comments LOD = 2.5 mg/kg (NO3-) and 5.0 mg/kg (NO2-) Quantification of 15N-labeled nitrate and nitrite biological fluids LOD = 10 nmol/L; RSD = 3 % (200 nmol/L) to 5% (400 nmol/L) Use of acid run buffer to revert electroosmotic flow LOD = 500 µg by use of a flame ionization detector Test strip equipped with sorghum leaf oxalate oxidase cross-linked with glutaraldehyde and o-toluidine LOD = 0.07% of the matrix Use of acid run buffer to revert electroosmotic flow LOD = 500 µg by use of a flame ionization detector Oxalate oxidase and peroxidase are immobilized on Au electrode Analysis of methylated product LOD = 6 µg/L to 9 µg/L Detection at = 254 nm; LOD = 20 nmol/L System attached to online weak anion exchange chromatography Intensity of peak at 1462 cm-1 is used Analysis of catalytic effect of reaction products of methylene blue/Cr2O7-2 Analysis of the NaDH NAD+ reaction with C2O4-2 Titration against MnO4Titration against Ce+4 Analysis of catalytic effect of reaction products of methylene blue/Cr2O7-2 Analysis of the NaDH NAD+ reaction with C2O4-2 Titration against MnO4Titration against Ce+4 Yb-pyrocatechol violet complex Determination of reddish-violet color produced by adding methylene blue/ZnSO4 in presence of NO3LOD = 0.2 ppb Analysis typically performed on tobacco plants Determination of organic basephosphate complex Use of cationic surfactants Titration against H-tetramethylammonium sulfate with various indicators Back titration of excess TiCl3 against Fe2(SO3)2 Use of 1037 cm-1 (Ca3(PO4)2) and 1010 cm-1 (MgNH4PO4)
Fungal Biodeterioration
Published in Thomas Dyer, Biodeterioration of Concrete, 2017
In at least one case, calcium oxalate was found to be absent at the fungi-inhabited surface of a cement paste specimen, despite analytical evidence that oxalic acid was being produced. It had previously been thought that once calcium oxalate was precipitated, fungi were subsequently unable to utilise the oxalate in any manner [81]. Recently, however, experiments conducted into calcium oxalate formation by a range of fungi found that, for some species, there was a subsequent disappearance of oxalate crystals [82]. It was proposed that the fungi were releasing enzymes such as decarboxylase or oxalate oxidase which were breaking down the oxalate to produce hydrogen peroxide (H2O2) which could be used in the oxidative decomposition of cellulose.
Optimization of oxalate-free starch production from Taro flour by oxalate oxidase assisted process
Published in Preparative Biochemistry & Biotechnology, 2021
Moni Philip Jacob Kizhakedathil, Suraksha Suvarna, Prasanna D. Belur, Rungtiwa Wongsagonsup, Esperanza Maribel G. Agoo, Jose Isagani B. Janairo
Oxalate oxidase (EC 1.2.3.4) catalyzes the oxidative cleavage of oxalate to carbon dioxide with the reduction of molecular oxygen to hydrogen peroxide.[15] Hydrogen peroxide being relatively unstable decomposes into water and molecular oxygen leaving behind with no undesirable residues. Total oxalates (soluble and insoluble) were removed by incubating taro flour with known amount of OxO enzyme. Earlier study on eddoe-type taro starch proved that oxalate present in the flour could be removed by treating the flour using OxO enzyme.[10] For the eddoe-type taro, Kumar and Belur[10] had performed a one factor at a time approach in order to maximize the oxalate removal. That study had mainly focused on enzyme load and incubation time. They had reported 97% oxalate reduction (790 mg/100 g to 24.2 mg/100 g) with 6 U OxO incubated for 120 min.[10] As the variety of taro taken in this study was different (dasheen type), the oxalate content was estimated in the beginning. The oxalate content in the taro flour was about 2344 mg/100 g DW, indicating the high acrid nature of the taro corms. Due to this, requirement of higher enzyme load and longer incubation period could be expected to bring down oxalate content in the resultant starch to an acceptable level. Hence, the range of chosen independent variables was fixed based on the studies of Kumar and Belur[10] and some degree of speculation. The OxO treatment was performed at 55 °C to prevent gelatinization of starch. After OxO treatment, taro flour slurry was homogenized and taro starch was extracted according to the protocol described earlier.