Patterned and switchable surfaces for biomaterial applications

Chapter 5 – Surface plasmon resonance imaging of polymer microarraysd[PB] ka[P][B] kd[ PB](5.3)dtThe surface concentration of the adsorbed species at saturation ( s∞ ) isproportional to the total number of surface binding sites ([B] + [PB]), thus, [B] isproportional to the difference of s∞ and [PB] (let [PB] = s ). As protein adsorptionexperiments are conducted under flow, [P] can be considered as a constant (C =concentration of bulk solution). Thus, equation 5.3 can be rewritten as equation 5.4and 5.5 [247].ddts k C( k (5.4)as s)dsddts k Cas kaC kd)( (5.5)sFrom equation 5.5 a plot of d s /dt against s would produce a straight line withslope equal to –(k a C +k d ) (). By producing this plot for a range of C, a plot of against C produces a straight line with slope equal to k a and a y-intercept of k d . Thebinding constant (K) can be found as k a /k d [247]. s∞ can by determined by assuming Langmuir binding between P and B. In thiscase, s is related to C by equation 5.6, which can be rearranged to give equation 5.7. s KC s1 KC(5.6)1 1 sK sC 1(5.7) sThus, s∞ can be determined from the y-intercept of the plot of the inverse of sagainst the inverse of C, and is given in units of mg/m 2 assuming a protein density of1.35 g/cm 3 [268].Curve fitting was conducted using Prism V 4.0c software.5-168