Figure 6.

Dependence of the measured kinetic rates for hybridization on the ionic strength. RPI binding curves were measured at a target concentration of 10 nM for different surface densities of probes (no linker type) and for different ionic strength, as indicated in the figure legend. The vertical error bars represent the standard deviation of observed rates calculated from three experiments at 150 mM NaCl. Horizontal error bars are relative errors estimated from mutliple RPI experiments with the same spotting concentrations of probes. The dashed curves are fits with exponential decay functions, constrained to the same asymptotic value at large s_p and to an initial value at s_p = 0 linearly increasing with the ionic strength. Inset: scaling of the reciprocal of the characteristic surface γ with the ionic strength obtained from the exponential decay fit of k_obs (red dots) and linear fit with slope 16 × 10⁻¹⁰ mm⁻²M⁻¹ (black line). To see this figure in color, go online.