A NEW AFFINITY BIOSENSOR - SELF-ASSEMBLED THIOLS AS SELECTIVE MONOLAYER COATINGS OF QUARTZ-CRYSTAL MICROBALANCES

We report on the use of quartz crystal microbalances (QCMs) for on-lin e detection of bioaffinity interactions. The QCM transducer is of reas onable simplicity as compared to other transducers used in direct affi nity sensing. However, the performance achieved with QCMs in liquids i s in many cases inferior to the performance achieved in air. We have i nvestigated the influence of several experimental parameters to improv e the stability and performance of QCM in liquids. With the aim of ach ieving a densely packed sensitive layer the Au substrates were examine d first with X-ray photoelectron spectroscopy (XPS) and scanning force microscopy (SFM). The successful immunological reaction of the subseq uently immobilized antigen and antibody was demonstrated by an enzyme linked immunosorbent assay (ELISA) experiment. The same immunological reaction [determination of antibodies against the foot-and-mouth-disea se virus (FMDV)] was then monitored with a QCM mounted in a flow-throu gh cell. The sensitive coating of the QCM could be regenerated for suc cessive use as mass sensitive biosensor.