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Bioanalytical device based on cholesterol oxidase-bonded SAM-modified electrodes.

Authors
  • Parra, A
  • Casero, E
  • Pariente, F
  • Vázquez, L
  • Lorenzo, E
Type
Published Article
Journal
Analytical and bioanalytical chemistry
Publication Date
Jul 01, 2007
Volume
388
Issue
5-6
Pages
1059–1067
Identifiers
PMID: 17340085
Source
Medline
License
Unknown

Abstract

A rapid, simple and reproducible two-step method for constructing cholesterol biosensors by covalently bonding cholesterol oxidase (ChOx) to a 3,3'-dithiodipropionic acid di(N-succinimidyl ester) (DTSP)-modified gold electrode is described. Exhaustive characterizations of both the immobilization process and the morphological properties of the resulting ChOx monolayer were performed via a quartz crystal microbalance (QCM) and atomic force microscopy (AFM) operated under liquid conditions, respectively. In addition, scanning electrochemical microscopy (SECM) measurements were performed in order to check that the immobilized enzyme retains its catalytic activity. The replacement of the natural electron acceptor (O(2)) in the enzymatic reaction with an artificial mediator, hydroxymethylferrocene (HMF), was also studied. Finally, cholesterol was amperometrically determined by measuring the hydrogen peroxide produced during the enzymatic reaction at +0.5 V. The optimized cholesterol biosensor exhibited a sensitivity of 54 nA mM(-1) and a detection limit of 22 microM.

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