title: Enhanced electrochemical sensitivity of enzyme precipitate coating (EPC)-based glucose oxidase biosensors with increased free CNT loadings.
abstract: Enzymatic electrodes were fabricated by using three different immobilizations of glucose oxidase (GOx): covalent enzyme attachment (CA), enzyme coating (EC), and enzyme precipitate coating (EPC), here referred to as CA-E, EC-E, and EPC-E, respectively. When additional carbon nanotubes (CNTs) were introduced from 0 to 75wt% for the EPC-E design, its initial biosensor sensitivity was improved from 2.40×10(-3) to 16.26×10(-3) A∙M(-1)∙cm(-2), while its electron charge transfer rate constant was increased from 0.33 to 1.47s(-1). When a fixed ratio of CNTs was added for three different electrode systems, EPC-E showed the best glucose sensitivity and long-term thermal stability. For example, when 75wt% of additional CNTs was added, the initial sensitivity of EPC-E was 16.26×10(-3) A∙M(-1)∙cm(-2), while those of EC-E and CA-E were only 6.42×10(-3) and 1.18×10(-3) A∙M(-1)∙cm(-2), respectively. Furthermore, EPC-E retained 63% of its initial sensitivity after thermal treatment at 40°C over 41days, while EC-E and CA-E showed only 12% and 1% of initial sensitivities, respectively. Consequently, the EPC approach with additional CNTs achieved both high sensitivity and long-term stability, which are required for continuous and accurate glucose monitoring.
authors.affiliation: Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Jae Hyun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Clean Energy Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Sun-Ae
authors.initials: SA
authors.lastname: Jun
authors.affiliation: Graduate School of Energy and Environment, Seoul National University of Science and Technology, Seoul 139-743, Republic of Korea.
authors.forename: Yongchai
authors.initials: Y
authors.lastname: Kwon
authors.affiliation: Department of Chemical Engineering, Washington State University, Pullman, WA 99164, USA.
authors.forename: Su
authors.initials: S
authors.lastname: Ha
authors.affiliation: Department of Chemical Engineering, Hanyang University, Seoul 133-791, Republic of Korea. Electronic address: biosang@hanyang.ac.kr.
authors.forename: Byong-In
authors.initials: BI
authors.lastname: Sang
authors.affiliation: Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea; Green School, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 136-713, Republic of Korea. Electronic address: jbkim3@korea.ac.kr.
authors.forename: Jungbae
authors.initials: J
authors.lastname: Kim
mesh_terms: D001674:Bioelectric Energy Sources; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D055664:Electrochemical Techniques / Q000295:instrumentation* / Q000379:methods; D004566:Electrodes; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D005947:Glucose / Q000032:analysis*; D005949:Glucose Oxidase / Q000737:chemistry* / Q000378:metabolism; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity
chemical_list: D004800:Enzymes, Immobilized; D037742:Nanotubes, Carbon; D005949:Glucose Oxidase; D005947:Glucose
keywords: Carbon nanotubes; Electron generation and transfer; Enzymatic glucose sensors; Enzyme precipitate coating; Glucose oxidase