title: Development of a stable cholesterol biosensor based on multi-walled carbon nanotubes-gold nanoparticles composite covered with a layer of chitosan-room-temperature ionic liquid network.
abstract: A novel amperometric biosensor was fabricated based on the immobilization of cholesterol oxidase (ChOx) into a cross-linked matrix of chitosan (Chi)-room-temperature ionic liquid (IL) (1-butyl-3-methylimidazolium tetrafluoroborate). Initially, the surface of bare electrode (indium tin oxide coated glass) was modified with the electrodeposition of Au particles onto thiol (-SH) functionalized multi-walled carbon nanotubes (MWNTs). The biosensor electrode is designated as MWNT(SH)-Au/Chi-IL/ChOx. Scanning electron microscopy image of MWNT(SH)-Au/Chi-IL/ChOx reveals that Chi-IL exists as the interconnected wires covering the Au particles on the surface of MWNT(SH)-Au. Cyclic voltammetry and chronoamperometry were used for the electrochemical determination of cholesterol at the biosensor electrode, MWNT(SH)-Au/Chi-IL/ChOx. The presence of Au particles in the matrix of CNTs provides an environment for the enhanced electrocatalytic activities. The MWNT(SH)-Au/Chi-IL/ChOx biosensor exhibited a linear response to cholesterol in the concentration range of 0.5-5mM with a correlation coefficient of 0.998, good sensitivity (200 microAM(-1)), a low response time ( approximately 7s), repeatability (R.S.D value of 1.9%) and long term stability (20 days with a decrease of 5% response). The synergistic influence of MWNT(SH), Au particles, Chi and IL contributes to the excellent performance for the biosensor.
authors.affiliation: Department of Chemistry Graduate School, Kyungpook National University, Daegu 702-701, South Korea.
authors.forename: Anantha Iyengar
authors.initials: AI
authors.lastname: Gopalan
authors.forename: Kwang-Pill
authors.initials: KP
authors.lastname: Lee
authors.forename: Dhanusuraman
authors.initials: D
authors.lastname: Ragupathy
mesh_terms: D000327:Adsorption; D015374:Biosensing Techniques / Q000295:instrumentation*; D048271:Chitosan / Q000737:chemistry*; D002784:Cholesterol / Q000032:analysis* / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry; D036103:Nanotechnology / Q000295:instrumentation*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D052578:Ionic Liquids; D037742:Nanotubes, Carbon; D006046:Gold; D048271:Chitosan; D002784:Cholesterol