Figure 4. Off rate of the HuEP / P-selectin bond as a function of the shear force is independent of the size of the molecular spacer between HuEP and the microparticle surface.

Comparison between chemisorbed (diamond), PEG³⁴⁰⁰ linkers (square), and PEG¹⁰⁰⁰⁰ linkers (triangle). The bond lifetime, microbead bond geometry, and shear parameters were fit into the Bell model to calculate the reactive bond compliance from the relationship between force and bond lifetimes under wall shear stress. The non-linear curve fit line was evaluated from Levenberg-Marquardt algorithm. The averaged fitted unstressed dissociation constant $k_{\mathit{\text{off}}}^o$ was 1.8 s⁻¹ with a bond compliance (σ) of 1.06 angstroms. Diagram of a microbead in static equilibrium and the estimation of force on a single bond (insert).