title: An amperometric cholesterol biosensor based on multiwalled carbon nanotubes and organically modified sol-gel/chitosan hybrid composite film.
abstract: A new type of amperometric cholesterol biosensor based on sol-gel chitosan/silica and multiwalled carbon nanotubes (MWCNTs) organic-inorganic hybrid composite material was developed. The hybrid composite film was used to immobilize cholesterol oxidase on the surface of Prussian blue-modified glass carbon electrode. Effects of some experimental variables such as enzyme loading, concentration of Triton X-100, pH, temperature, and applied potential on the current response of the biosensor were investigated. Analytical characteristics and dynamic parameters of the biosensors with and without MWCNTs in the hybrid film were compared, and the results show that analytical performance of the biosensor can be improved greatly after introduction of the MWCNTs. Response time, sensitivity, linear range, limit of detection (S/N=3), and apparent Michaelis-Menten constant Km are 25s, 0.54 microA mM(-1), 8.0 x 10(-6) to 4.5 x 10(-4) M, 4.0 x 10(-6) M, and 0.41 mM for the biosensor without MWCNTs and 13 s, 1.55 microA mM(-1), 4.0 x 10(-6) to 7.0 x 10(-4) M, 1.0 x 10(-6) M, and 0.24 mM for the biosensor with MWCNTs, respectively. The activation energy of the enzyme-catalyzed reaction was measured to be 42.6 kJ mol(-1). This method has been used to determine the free cholesterol concentration in real human blood samples.
authors.affiliation: School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China.
authors.forename: Xuecai
authors.initials: X
authors.lastname: Tan
authors.forename: Minjian
authors.initials: M
authors.lastname: Li
authors.forename: Peixiang
authors.initials: P
authors.lastname: Cai
authors.forename: Lijun
authors.initials: L
authors.lastname: Luo
authors.forename: Xiaoyong
authors.initials: X
authors.lastname: Zou
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D048271:Chitosan; D002784:Cholesterol / Q000032:analysis / Q000097:blood*; D002789:Cholesterol Oxidase; D004566:Electrodes; D004800:Enzymes, Immobilized; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon; D044367:Phase Transition; D013696:Temperature
chemical_list: D004800:Enzymes, Immobilized; D037742:Nanotubes, Carbon; D048271:Chitosan; D002784:Cholesterol; D002789:Cholesterol Oxidase