A more detailed analysis of QCM-D data revealed further insight into the adsorption process of BMPs to PSPMA brushes and the impact of their architecture. On thick dense brushes (HD-30), upon binding of BMP2, the third harmonic frequency decreased, but other harmonics increased, and the dissipation signal decreased with increasing harmonic numbers (Figure ). This may be explained by the binding of BMP2 only at the top of the brush, coupled with some release of solvent from the bulk of the brush. In contrast, with thin dense brushes (HD-10) the smaller the overtone the smaller the dissipation shift. This may be explained by an improved penetration of BMP2 inside the brush (or non-specifically at the surface of the crystal ). This observation is in agreement with the reduced kinetics of adsorption observed by SPR (Figure ).