Direct electrochemistry and electrocatalysis of hemoglobin immobilized into poly (lactic- co-glycolic acid)/room temperature ionic liquid composite film

Abstract

A promising material of poly(lactic- co-glycolic acid) (PLGA) and, room temperature ionic liquid (ILs) (1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF 4) was firstly used as an immobilization matrix to entrap proteins and its bioelectrochemical properties were studied. Direct electrochemistry and electrocatalytic behaviors of hemoglobin (Hb) entrapped in the PLGA/ILs composite film on the surface of glass carbon electrode were investigated. UV–vis spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the composite film. The obtained results demonstrated that the Hb molecule in the film kept its native structure and showed its good electrochemical behavior. A pair of well-defined redox peaks of Hb was obtained at the Hb/PLGA/ILs composite film-modified GC electrode through direct electron transfer between the protein and the underlying electrode. The proposed biosensor showed good reproducibility and high sensitivity to H 2O 2 with the detection limit of 2.37 × 10 −7 M (S/N = 3). In the range of 5.0 × 10 −6 to 8.05 × 10 −3 M, the catalytic reduction current of H 2O 2 was proportional to its concentration. The apparent Michaelis–Menten constant of Hb in the PLGA/ILs composite film was estimated to be 0.069 mM, showing its high affinity.