Biocompatible hybrid film of β-cyclodextrin and ionic liquids: A novel platform for electrochemical biosensing

A novel electrochemical biosensing platform was developed based on the modification of biocompatible hybrid film of β-cyclodextrin (β-CD) and ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) onto glass carbon electrode (GCE). Then an unmediated biosensor was successfully prepared by immobilizing the horseradish peroxidase (HRP) into the β-CD/ILs composite film. β-CD could provide a biocompatible microenvironment for HRP, and ILs could accelerate the electron transfer between HRP and the electrode. Results showed that the HRP entrapped in the β-CD/ILs film could maintain its native structure and the direct electrochemistry of HRP were facilely achieved. A couple of well-defined redox peaks of HRP were observed at about −0.32 V (vs. SCE), corresponding to the protein heme Fe(III)/Fe(II) redox couples. The electrocatalysis of this biosensor to both quercetin and hydrogen peroxide was characterized. The biosensor exhibited a low operating potential (−0.05 V vs. SCE), fast amperometric response, high sensitivity, good selectivity and sub-micromolar limit of detection.