Application of Room Temperature Ionic Liquids to the Development of Electrochemical Lipase Biosensing Systems for Water-Insoluble Analytes

摘要

Biosensors have been prepared by modification of glassy carbon electrodes withfunctionalised multiwalled carbon nanotubes (MWCNT) dispersed in the room temperatureionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonimide (BmimNTF2)and with lipase cross-linked with glutaraldehyde. The biosensor was applied to thedetermination of olive oil triglycerides by cyclic voltammetry. A phosphate buffer (pH 7.0) /BmimNO3 mixture is a better electrolyte than aqueous buffer alone. The response signal in thebuffer-BmimNO3 mixture was found to increase with the number of cycles until a constantcurrent was achieved. The calibration curve obtained exhibited a sigmoid-shape and a fourparametermodel was used to fit the data which gave a limit of detection of 0.11 μg mL−1.Close inspection of such calibration curves showed two distinct linear regions indicatingchanges in the mechanism of the electrochemical response. Overall, the oxidative analyticalresponse was found to be due to phenolic compounds present in the olive oil, released in thepresence of lipase, rather than due to triglycerides per se. It was also found that there were nointerferences from either cholesterol or glycerol. A possible mechanism of olive oildetermination at a MWCNT-BmimNTF2/Lip biosensor is proposed.