title: Fabrication of a novel dual mode cholesterol biosensor using titanium dioxide nanowire bridged 3D graphene nanostacks.
abstract: Herein, we fabricated a novel electrochemical-photoelectrochemical (PEC) dual-mode cholesterol biosensor based on graphene (G) sheets interconnected-graphene embedded titanium nanowires (TiO2(G)-NWs) 3D nanostacks (designated as G/Ti(G) 3DNS) by exploiting the beneficial characteristics of G and TiO2-NWs to achieve good selectivity and high sensitivity for cholesterol detection. The G/Ti(G) 3DNS was fabricated by the reaction between functionalized G and TiO2(G)-NWs. Cholesterol oxidase (ChOx) was subsequently immobilized in to G/Ti(G) 3DNS using chitosan (CS) as the binder and the dual mode G/Ti(G) 3DNS/CS/ChOx biosensor was fabricated. The electro-optical properties of the G/Ti(G) 3DNS/CS/ChOx bioelectrode were characterized by cyclic voltammetry and UV-vis diffuse reflection spectroscopy. The cyclic voltammetry of immobilized ChOx showed a pair of well-defined redox peaks indicating direct electron transfer (DET) of ChOx. The amperometric reduction peak current (at -0.05V) linearly increased with increase in cholesterol concentration. The G/Ti(G) 3DNS/CS/ChOx bioelectrode was selective to cholesterol with a remarkable sensitivity (3.82μA/cm(2)mM) and a lower detection limit (6μM). Also, G/Ti(G) 3DNS/CS/ChOx functioned as photoelectrode and exhibited selective detection of cholesterol under a low bias voltage and light irradiation. Kinetic parameters, reproducibility, repeatability, storage stability and effect of temperature and pH were evaluated. We envisage that G/Ti(G) 3DNS with its prospective characteristics, would be a promising material for wide range of biosensing applications.
authors.affiliation: Deparment of Chemistry Education, Kyungpook National University, Daegu, South Korea.
authors.forename: S
authors.initials: S
authors.lastname: Komathi
authors.affiliation: Deparment of Chemistry Education, Kyungpook National University, Daegu, South Korea.
authors.forename: N
authors.initials: N
authors.lastname: Muthuchamy
authors.affiliation: Deparment of Chemistry Education, Kyungpook National University, Daegu, South Korea; Department of Nanoscience and Nanotechnology, Kyungpook National University, Daegu, South Korea.
authors.forename: K-P
authors.initials: KP
authors.lastname: Lee
authors.affiliation: Research Institute of Advanced Energy Technology, Kyungpook National University, Daegu, South Korea; Department of Nanoscience and Nanotechnology, Kyungpook National University, Daegu, South Korea. Electronic address: algopal_99@yahoo.com.
authors.forename: A-I
authors.initials: AI
authors.lastname: Gopalan
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D002784:Cholesterol / Q000097:blood*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D053770:Nanowires / Q000737:chemistry / Q000648:ultrastructure; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D006108:Graphite; D002784:Cholesterol; D014025:Titanium
keywords: Cholesterol; Direct electron transfer; Graphene; Nanostacks; Photoelectrochemical; Titanium dioxide