title: Multienzymatic-rotating biosensor for total cholesterol determination in a FIA system.
abstract: Fabrication of an amperometric-rotating biosensor for the enzymatic determination of cholesterol is reported. The assay utilizes a combination of three enzymes: cholesterol esterase (ChE), cholesterol oxidase (ChOx) and peroxidase (HRP); which were co-immobilizing on a rotatory disk. The method is developed by the use of a glassy carbon electrode as detector versus Ag/AgCl/3M NaCl in conjunction with a soluble-redox mediator 4-tert-butylcatechol (TBC). ChE converts esterified cholesterol to free cholesterol, which is then oxidized by ChOx with hydrogen peroxide as product. TBC is converted to 4-tert-butylbenzoquinone (TBB) by hydrogen peroxide, catalyzed by HRP, and the glassy carbon electrode responds to the TBB concentration. The system has integrated a micro packed-column with immobilized ascorbate oxidase (AAOx) that works as prereactor to eliminate l-ascorbic acid (AA) interference. This method could be used to determine total cholesterol concentration in the range 1.2muM-1mM (r=0.999). A fast response time of 2min has been observed with this amperometric-rotating biosensor. Lifetime is up to 25 days of use. The calculated detection limits was 11.9nM. Reproducibility assays were made using repetitive standards solutions (n=5) and the percentage standard error was less than 4%.
authors.affiliation: Department of Chemistry, National University of San Luis, Chacabuco y Pedernera, 5700 San Luis, Argentina.
authors.forename: Eloy
authors.initials: E
authors.lastname: Salinas
authors.forename: Valeria
authors.initials: V
authors.lastname: Rivero
authors.forename: Angel A J
authors.initials: AA
authors.lastname: Torriero
authors.forename: Delia
authors.initials: D
authors.lastname: Benuzzi
authors.forename: María I
authors.initials: MI
authors.lastname: Sanz
authors.forename: Julio
authors.initials: J
authors.lastname: Raba