QUARTZ-CRYSTAL MICROBALANCE BIOAFFINITY SENSOR FOR BIOTIN

A quartz crystal microbalance (QCM) bioaffinity sensor for biotin, based on the bioaffinity complex between avidin and immobilized desthiobiotin, was established. BSA-desthiobiotin conjugate was adsorbed directly onto the gold layer surface of a quartz crystal. The crystal was placed in a QCM flow cell. Avidin formed a metastable complex with the BSA-desthiobiotin conjugate on the crystal surface. When a sample solution containing biotin was injected, the avidin was released from the surface to form a more stable complex with biotin in solution. The biotin concentration corresponded to the weight change on the crystal surface that occurred when avidin desorbed. Measurements were done in the stop-flow mode with a measurement range between 0.05 and 100 mu g/mL and in the continuous-flow mode with a measurement range between 0.2 and 10 000 mu g/mL. The sensor was regenerated without any loss of activity by readsorbing avidin.