Molecularly imprinted polymer thin film based surface plasmon resonance sensor to detect hemoglobin

Molecularly imprinted polymer(MIP) films for hemoglobin detection were prepared onto the Au/Cr coated surface plasmon resonance(SPR) sensor chips by the in situ electropolymerization of 3-aminophenylboronic acid(3-APBA). The formation of the films and rebinding processes of hemoglobin were monitored by in situ electrochemical-SPR(EC-SPR) spectroscopy, with allowed real-time observation of the simultaneous changes in electrochemical and optical properties of the films. Scanning electron microscopy(SEM) and atomic force microscopy(AFM) were used to characterize the surface morphologies of the MIP films. The effects of pH, ion strength, different metal ions on rebinding Hb, the specific binding and the selective recognition were investigated. The results obtained with the molecular imprinted SPR chips indicate a good adsorption of Hb in a range of 0.0005-5 mg/mL in 0.05 mol/L sodium phosphate buffer at pH=7.0. A linear calibration curve(R ²=0.94) of the SPR sensor for Hb detection was obtained in a range of 0.05-5 mg/mL. The detection limit for hemoglobin by this method was 0.000435 mg/mL(S/N=3). Interference studies indicate that the MIP films have a good selectivity compared with the referenced proteins. The stability of the sensor was also established. Results indicate that the SPR sensor chip keeps 87.6% of its original response after 14 d of storage under dry and ambient conditions.