An electrochemical tyrosinase-immobilized biosensor for albumin - toward a potential total protein measurement

A simple biosensor, based on a tyrosinase-immobilized electrode, was developed for a rapid and quantitative measurement of bovine serum albumin (BSA) and human serum albumin (HSA). Tyrosinase, immobilized on a screen-printed carbon electrode, catalyzed the oxidation of tyrosine residues in the albumin to the corresponding quinone, which was further reduced electrochemically by the sensing electrode under an appropriate condition. The concentration of the protein, therefore, could be quantified by measuring the reduction current. The operational parameters that affect the performance of this biosensor, e.g., the working potential, the pH value, and the temperature, were assessed and optimized. The stability, the lifetime, and the reproducibility of this biosensor were also evaluated. This biosensor demonstrated that it was not only a highly sensitive assay for albumin but will be a potential tool for the measurement of total protein in human serum. (c) 2005 Elsevier B.V. All rights reserved.