Highly stable enzyme precipitate coatings and their electrochemical applications |
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Authors: | Kim Byoung Chan Zhao Xueyan Ahn Hye-Kyung Kim Jae Hyun Lee Hye-Jin Kim Kyung Woo Nair Sujith Hsiao Erik Jia Hongfei Oh Min-Kyu Sang Byoung In Kim Beom-Soo Kim Seong H Kwon Yongchai Ha Su Gu Man Bock Wang Ping Kim Jungbae |
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Institution: | Environment Division, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea. |
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Abstract: | This paper describes highly stable enzyme precipitate coatings (EPCs) on electrospun polymer nanofibers and carbon nanotubes (CNTs), and their potential applications in the development of highly sensitive biosensors and high-powered biofuel cells. EPCs of glucose oxidase (GOx) were prepared by precipitating GOx molecules in the presence of ammonium sulfate, then cross-linking the precipitated GOx aggregates on covalently attached enzyme molecules on the surface of nanomaterials. EPCs-GOx not only improved enzyme loading, but also retained high enzyme stability. For example, EPC-GOx on CNTs showed a 50 times higher activity per unit weight of CNTs than the conventional approach of covalent attachment, and its initial activity was maintained with negligible loss for 200 days. EPC-GOx on CNTs was entrapped by Nafion to prepare enzyme electrodes for glucose sensors and biofuel cells. The EPC-GOx electrode showed a higher sensitivity and a lower detection limit than an electrode prepared with covalently attached GOx (CA-GOx). The CA-GOx electrode showed an 80% drop in sensitivity after thermal treatment at 50°C for 4 h, while the EPC-GOx electrode maintained its high sensitivity with negligible decrease under the same conditions. The use of EPC-GOx as the anode of a biofuel cell improved the power density, which was also stable even after thermal treatment of the enzyme anode at 50°C. The excellent stability of the EPC-GOx electrode together with its high current output create new potential for the practical applications of enzyme-based glucose sensors and biofuel cells. |
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