Immobilization of bovine serum albumin as a sensitive biosensor for the detection of trace lead ion in solution by piezoelectric quartz crystal impedance

A biosensor based on bovine serum albumin (BSA) for the detection of lead (Pb2+) ion was developed and characterized. BSA was immobilized onto a colloidal Au-modified piezoelectric quartz crystal (PQC) as a biosensor for the detection of Pb2+ ion by piezoelectric quartz crystal impedance (PQCI). Calibration curves for the quantification of Pb2+ ion showed excellent linearity throughout the concentration range from 1.0 × 10−7 to 3.0 × 10−9 mol/L. The interaction between the Pb2+ ions and the sensor chip is influenced significantly by the pH of the reaction buffer, and the optimal pH for the experiment was 5.4. Under the optimal conditions, the detection limit of 1.0 × 10−9 mol/L for Pb2+ was obtained. Kinetic parameters of the Pb2+–BSA interactions were also determined by using this chip. The sensor chip could be regenerated for use by dipping in the ethylenediaminetetraacetic acid (EDTA) solution for approximately 2 h, and the chip was used to detect Pb2+ ion for eight times without obvious signal attenuation.