title: Highly-sensitive cholesterol biosensor based on well-crystallized flower-shaped ZnO nanostructures.
abstract: This paper reports the fabrication of highly-sensitive cholesterol biosensor based on cholesterol oxidase (ChOx) immobilization on well-crystallized flower-shaped ZnO structures composed of perfectly hexagonal-shaped ZnO nanorods grown by low-temperature simple solution process. The fabricated cholesterol biosensors reported a very high and reproducible sensitivity of 61.7 microA microM(-1)cm(-2) with a response time less than 5s and detection limit (based on S/N ratio) of 0.012 microM. The biosensor exhibited a linear dynamic range from 1.0-15.0 microM and correlation coefficient of R=0.9979. A lower value of apparent Michaelis-Menten constant (K(m)(app)), of 2.57 mM, exhibited a high affinity between the cholesterol and ChOx immobilized on flower-shaped ZnO structures. Moreover, the effect of pH on ChOx activity on the ZnO modified electrode has also been studied in the range of 5.0-9.0 which exhibited a best enzymatic activity at the pH range of 6.8-7.6. To the best of our knowledge, this is the first report in which such a very high-sensitivity and low detection limit has been achieved for the cholesterol biosensor by using ZnO nanostructures modified electrodes.
authors.affiliation: Department of Chemistry, Faculty of Science, Najran University, Najran, Kingdom of Saudi Arabia. ahmadumaresn@gmail.com
authors.forename: Ahmad
authors.initials: A
authors.lastname: Umar
authors.forename: M M
authors.initials: MM
authors.lastname: Rahman
authors.forename: A
authors.initials: A
authors.lastname: Al-Hajry
authors.forename: Y-B
authors.initials: YB
authors.lastname: Hahn
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods* / Q000592:standards; D002784:Cholesterol / Q000032:analysis*; D002789:Cholesterol Oxidase / Q000378:metabolism; D003460:Crystallization; D004800:Enzymes, Immobilized / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D049329:Nanostructures / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D002784:Cholesterol; D002789:Cholesterol Oxidase; D015034:Zinc Oxide