Replacement-free electrodeless quartz crystal microbalance biosensor using nonspecific-adsorption of streptavidin on quartz.

This paper proposes a replacement-free and surface-modification-free quartz crystal microbalance (QCM) biosensor. With the use of significant nonspecific adsorption of streptavidin on naked quartz surfaces, target analyte is detected through biotin-tagged receptors on streptavidin. The wireless-electrodeless QCM technique is developed with a 30 microm thick AT-cut quartz plate, whose fundamental resonance frequency is 55 MHz, and the naked quartz surfaces are used for the nonspecific adsorption of streptavidin. Once it is installed in the sensor cell, it can be used semipermanently; it never needs to be replaced. The equilibrium dissociation constant of streptavidin on quartz is determined to be 1.3 x 10(-7) M. The flow rate affected the number of the adsorbed streptavidin on quartz as well as the binding velocity.