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 mV s −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.