Design of carbon paste biosensors based on the mixture of ionic liquid and paraffin oil as a binder for high performance and stabilization

This paper reports on the preparation and advantages of novel amperometric biosensors in the presence of hydrophobic ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). Carbon paste biosensors have been constructed by entrapping heme proteins in carbon + IL mixed with paraffin oil as a binder. The most suitable paste composite was determined according to the catalytic activity of the biosensors to H2O2. The simplified preparations of the biosensors display advantages of a high sensitivity, a wide linear range, and a good activity toward H2O2. The IL-contained paste enhances high stability (thermal, pH, and operational) onto the immobilized heme proteins. Moreover, the biosensors could still maintain their good activity and the sensitivity after 3-month storage when keeping in the dry state in a refrigerator at 4 °C. The resulting biosensors are suitable for the precise determination of H2O2 in actual environment.