QUARTZ-CRYSTAL MICROBALANCE BIOAFFINITY SENSOR FOR BIOTIN

A quartz crystal microbalance (QCM) bioaffinity sensor for biotin, bas ed on the bioaffinity complex between avidin and immobilized desthiobi otin, was established. BSA-desthiobiotin conjugate was adsorbed direct ly onto the gold layer surface of a quartz crystal. The crystal was pl aced in a QCM flow cell. Avidin formed a metastable complex with the B SA-desthiobiotin conjugate on the crystal surface. When a sample solut ion containing biotin was injected, the avidin was released from the s urface to form a more stable complex with biotin in solution. The biot in concentration corresponded to the weight change on the crystal surf ace 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 a nd in the continuous-flow mode with a measurement range between 0.2 an d 10 000 mu g/mL. The sensor was regenerated without any loss of activ ity by readsorbing avidin.