Adhesion of human platelets to collagen detected by 51Cr labelling and acoustic wave sensor

Selective adhesion of human platelets to layers of collagen Type I, immobilized on silicon wafers, has been confirmed using 51Cr radiolabelling of platelets. Corresponding experiments conducted with collagen-treated thickness-shear mode acoustic wave sensors resulted in changes in series resonant frequency in the range 35–43 Hz. Control experiments with sensors, coated with bovine serum albumin, displayed significantly reduced response. Similar reduced values were also obtained when EDTA was present and Mg2+ was absent from the assay-buffer solution. Direct correlation of the sensor results with 51Cr labelling experiments confirms that the conventional quartz crystal microbalance description is completely inadequate to explain the magnitude of the sensor response, which is 200 times less than that predicted by the well-known Sauerbrey expression.