Electrochemical biosensing platforms using poly-cyclodextrin and carbon nanotube composite.

Carbon nanotubes (CNTs) were "dissolved" in mixed solution of cyclodextrin (CD) and cyclodextrin prepolymer (pre-CDP) and were used as modifier to fabricate chemical modified electrode. The dispersions of CNTs in different solutions were characterized using UV-vis spectrophotometer. The insoluble conducting composite film of poly-cyclodextrin (CDP) and carbon nanotube was synthesized, and glucose oxidase (GOx) was immobilized on the film to fabricate amperometric biosensor. The CNT-CDP electrode was stable. It can keep the exceptional chemical and physical properties of CNTs and the host-guest chemical reaction ability of cyclodextrins. Cyclic voltammetry measurements of potassium ferricyanide solution (50 mM, and scan rate 100 mVs(-1)) shows that the CDP film was compact and the CNT-CDP film maintains the electrocatalytic activity of CNT. Glucose oxidase was used as a model enzyme to prepare a glucose biosensor. The bioactivity of immobilized glucose oxidase was maintained due to the biocompatibility of cyclodextrin. Amperometric measurements were done with different concentrations of glucose. The CNT-CDP/GCE-GOx biosensor has wide concentration ranges and good sensitivity to glucose. It showed a detection limit of 3.5 μM with a linear range from 0.004 to 3.23 mM and from 4.26 to 10.00 mM. In addition, the biosensor can be operated under wide pH range (pH 5.6-7.8) without great changes in its sensitivity. Copyright 2010 Elsevier B.V. All rights reserved.