Xanthine oxidase (XO) amperometric biosensor for antioxidant determination of orthosiphon stamineus benth extracts

Simple item page
dc.contributor.authorKwan, Wei Yen
dc.date.accessioned2014-10-27T08:49:48Z
dc.date.available2014-10-27T08:49:48Z
dc.date.issued2009
dc.descriptionMasteren_US
dc.description.abstractAn amperometric chitosan-based xanthine oxidase membrane biosensor for evaluation of xanthine oxidase inhibition capacity of Orthosiphon stamineus extract samples is studied. The fabrication process involves entrapment of xanthine oxidase on a modified chitosan membrane to retain the natural environment of the enzyme. The biosensor showed optimum current response and linear range at 0.001 Units of immobilized xanthine oxidase based on its linearity and current response using pH 5.0 chitosan solution to form the sensing membrane to entrap xanthine oxidase molecules. The optimum pH value of working buffer is 7.0, indicating the enzyme molecules were immobilized in an environment similar to its presence in free solution. The biosensor showed drastic decrease in performance after one week of storage then remains at a plateau starting at week two until week three before another drastic decrease occurred. The biosensor displayed 17.75% of its original activity after four weeks of storage. The calibration curve was linear in the range of 5.0 × 10-7 M to 4.3 × 10-5 M xanthine with detection limit (S/N=3) of 1.5 × 10-7 M, operating at potential 600 mV vs. silver/silver chloride as reference electrode. The Hanes plot of the biosensor gives K‟m value of 25.33 μM, lower that all the xanthine oxidase based biosensors. The usefulness of the biosensor for the herbal extract antioxidant assay was demonstrated by determining the percentage of XO inhibition of Orthosiphon stamineus Benth extracts, as compared with the spectrophotometric method. The results from the T test showed that the biosensor and UV-Visible spectrophotometry method have a high correlation of 0.829.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/180
dc.language.isoenen_US
dc.subjectPharmaceutical scienceen_US
dc.subjectXanthine oxidaseen_US
dc.subjectAntioxidanten_US
dc.titleXanthine oxidase (XO) amperometric biosensor for antioxidant determination of orthosiphon stamineus benth extractsen_US
dc.typeThesisen_US
Files
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Pusat Pengajian Sains Farmasi - Tesis