Enzyme entrapment by β-cyclodextrin electropolymerization onto a carbon nanotubes-modified screen-printed electrode

A novel enzyme entrapment approach based on an electropolymerization process utilizing multi-walled carbon nanotubes (MWCNT), beta-cyclodextrin (beta-CD) and glucose oxidase (GOx) is shown. Dopamine (DA) quantification is presented using a screen-printed electrode modified by electropolymerization of cyclodextrin with glucose oxidase, SPE/MWCNT/beta-CD-GOx. In order to show the relevance of the enzyme entrapment strategy controlled by electropolymerization to develop a specific and efficient biosensor, the various parts composing the electrode: SPE, SPE/beta-CD, SPE/GOx, SPE/beta-CD/GOx, SPE/MWCNT/beta-CD, SPE/MWCNT/GOx and SPE/MWCNT/beta-CD/GOx were tested separately. It was shown that although DA determination can be achieved with all of them, the electrodes modified with MWCNT presented better analytical features that those built without MWCNT, the best being the one including all components. This biosensor displayed good reproducibility, repeatability, and prolonged life-time under cold storage conditions. Its DA limit of detection (LOD) was 0.48+/-0.02 mu A in a linear range of 10-50 mu M with a sensitivity of 0.0302+/-0.0003 mu A mu M-1 that makes it comparable or even better than many other electrodes reported in the literature. Moreover, it was also shown that using this electrode, DA quantification can be done in the presence of interfering agents such as ascorbic and uric acid. These findings demonstrate that the approach employed is feasible for enzyme entrapment and may find applications in other biosensing systems, where better sensitivity, stability and fast response are required. (C) 2010 Elsevier B.V. All rights reserved.