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KMID : 1094720160210040573
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Biotechnology and Bioprocess Engineering
2016 Volume.21 No. 4 p.573 ~ p.579
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Immobilization of glucose oxidase on graphene oxide for highly sensitive biosensors
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Hong Sung-Gil
Kim Jae-Hyun
Kim Ryang-Eun
Kwon Seok-Joon
Kim Dae-Woo
Jung Hee-Tae
Dordick Jonathan S.
Kim Jung-Bae
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Abstract
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Glucose oxidase (GOx) was immobilized onto graphene oxide (GRO) via three different preparation methods: enzyme adsorption (EA), enzyme adsorption and crosslinking (EAC), and enzyme adsorption, precipitation and crosslinking (EAPC). EAPC formulations, prepared via enzyme precipitation with 60% ammonium sulfate, showed 1,980 and 1,630 times higher activity per weight of GRO than those of EA and EAC formulations, respectively. After 59 days at room temperature, EAPC maintained 88% of initial activity, while EA and EAC retained 42 and 45% of their initial activities, respectively. These results indicate that the steps of precipitation and crosslinking in the EAPC formulation are critical to achieve high enzyme loading and stability of EAPC. EA, EAC and EAPC were used to prepare enzyme electrodes for use as glucose biosensors. Optimized EAPC electrode showed 93- and 25-fold higher sensitivity than EA and EAC, respectively. To further increase the sensitivity of EAPC electrode, multi-walled carbon nanotubes (MWCNTs) were mixed with EAPC for the preparation of enzyme electrode. Surprisingly, the EAPC electrode with additional 99.5 wt% MWCNTs showed 7,800-fold higher sensitivity than the EAPC electrode without MWCNT addition. Immobilization and stabilization of enzymes on GRO via the EAPC approach can be used for the development of highly sensitive biosensors as well as to achieve high enzyme loading and stability.
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KEYWORD
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enzyme adsorption/precipitation/crosslinking, glucose oxidase, graphene oxide, biosensors, carbon nanotubes
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