Activation of polyvinyl chloride sheet surface for covalent immobilization of oxalate oxidase and its evaluation as inert support in urinary oxalate determination

A novel amperometric biosensor for rapid detection of ethanol utilizing gold nanoparticles and enzyme coupled PVC reaction cell

This research was aimed at the fabrication of an improved enzyme-based amperometric biosensor for rapid quantification of ethanol. Alcohol oxidase (AOX) from Pichia pastoris was covalently immobilized on chemically treated polyvinylchloride (PVC) beaker and subsequently horseradish peroxidase (HRP), nafion (Nf), carboxylated multi-walled carbon nanotubes (c-MWCNTs), chitosan (CHIT) and gold nanoparticles (AuNPs) were immobilized onto Au electrode to fabricate a working electrode. The enzyme-coated PVC surface was analysed morphologically via scanning electron microscopy (SEM). At different stages of construction, the electrochemical properties of working electrode were deciphered by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The biosensor displayed optimal response in a short time span of 12 s at pH 7.5 and 35°C temperature. The working range exhibited by the proposed biosensor was 0.01-42 mM with a limit of detection (LOD) of 0.0001 µM and storage stability of 180 days at 4°C. When level of alcohol was evaluated in commercial samples via standard assay kit and existing biosensor, a good correlation (R²= 0.98) was observed which authenticates its reliability.

Manipulation of oxalate metabolism in plants for improving food quality and productivity

Oxalic acid is a naturally occurring metabolite in plants and a common constituent of all plant-derived human diets. Oxalic acid has diverse unrelated roles in plant metabolism, including pH regulation in association with nitrogen metabolism, metal ion homeostasis and calcium storage. In plants, oxalic acid is also a pathogenesis factor and is secreted by various fungi during host infection. Unlike those of plants, fungi and bacteria, the human genome does not contain any oxalate-degrading genes, and therefore, the consumption of large amounts of plant-derived oxalate is considered detrimental to human health. In this review, we discuss recent biotechnological approaches that have been used to reduce the oxalate content of plant tissues.

Covalent immobilization of mixed proteases, trypsin and chymotrypsin, onto modified polyvinyl chloride microspheres

A commercially available trypsin-chymotrypsin mixture was covalently immobilized onto modified polyvinyl chloride (PVC) microspheres, which were activated by the subsequent treatment of PVC microspheres with ethylenediamine and glutaraldehyde. The immobilized mixed protease was characterized by FT-IR and SEM analyses. Immobilization conditions were optimized by Box-Behnken design and the response surface method. The activity of the immobilized mixed protease prepared under optimal conditions (pH 6.6, 23 °C, 2 h) reached 1341 U/g. Compared with the free form, the immobilized enzyme possesses a slightly higher optimal pH value and a wider pH-activity profile, superior thermal stability, and a higher Km value. Reusability of the immobilized mixed protease indicated that >70% of the original activity was retained after having been recycled six times.