Figure 2.

BFP thermal fluctuation assay. (A) In each test cycle, the target bead first approached the probe bead (black), stayed in contact for 0.1 s (green), retracted (purple), and was held in space (blue/red). (B) Plot of sliding standard deviation (Std.) of 90 consecutive points (σ₉₀) of the probe position in (A) versus time t. Horizontal lines represent the threshold values to identify bond association (solid line) and dissociation (dashed line) events. Bond and no-bond states were distinguished in red and blue segments, respectively. (C) Adhesion frequencies between target beads coated with GC and probe beads coated with A1 (A1(+), first column), without A1 (A1(−), second column), with A1 + 50 μg/mL anti-A1 blocking mAb 5D2 (+anti-A1, third column), and with A1 plus 50 μg/mL anti-GPIbα blocking mAb AK2 (+anti-GPIbα, fourth column). Binding frequencies, represented as mean ± SE, were measured from three probe-target pairs per condition and each probe-target pair was tested repeatedly for 100 contact-retract cycles. To see this figure in color, go online.