Figure 3. Bond dissociation constants (koff) are lowered by increasing the length of the HuEP-PEG spacer on the microparticle.
Distributions of the lifetimes of the transient adhesions were used to calculate the bond dissociation constants (koff) of chemisorbed, PEG3400, and PEG10000 linked HuEP microparticles interacting with the P-selectin surface at wall shear stresses of 0.1 dynes/cm2, 0.4 dynes/cm2, and 1.0 dynes/cm2. The relationship between koff and wall shear rate was determined for (grey) chemisorbed, (black) PEG3400 and (white) PEG10000 linked microparticles. The P- selectin surface site density was 100 sites/µm2. R2 > 0.94 for the bi-molecular reaction model equation: ln[C] = −koff t + constant. 26,37 Dissociation constant differences that achieve significance are indicated by asterisk (* p<0.01) for HuEP3400 koff versus chemisorbed HuEP and (** p<.01) for HuEP10000 koff versus chemisorbed HuEP koff.