Measurement of the Biotin Concentration Using QCM Biosensors

This paper presents a novel Ni-Co alloy coated QCM biosensor fabricated by electroplating nickel and cobalt on the surface of 10-MHz AT-cut QCM. The biotin was immobilized on the coated surface by the affinity mechanism of Ni-Co alloy. Then, the immunoreactions can be performed on the QCM biosensors. The results show that the Ni-Co alloy coated QCM biosensor can provide specific binding with His-tagged biotin. For different biotin concentrations, the QCM produced different frequency shifts. In addition, fluorescent detection was also performed to show that the coated Ni-Co film has better nonspecific binding ability than nitrocellulose film to immobilize His-tagged proteins for target analyses. The advantages of this biosensor include: (1) label-free detection based on the principle of QCM resonator; (2) minimal sample consumption (0.5 mul of biotin each drop used in this study); (3) inexpensive fabrication process using the well-developed electroplating technique.