Regulating polymer adsorption on colloid by surface morphology

The study of polymer adsorption on colloidal particles has attracted intensive attention. In this work, we investigated polymer adsorption on substrate colloidal particles with two complementary morphologies, one of which has bulges (raspberry-like) on the surface and the other of which has holes instead (strawberry-like). Compared to the bulges, the holes on the colloidal particles were found to prevent polymer adsorption and this effect was dependent on the relative dimensions of the polymer coil and hole. This surface morphology effect was attributed mainly to the reduced polymer accessibility to the adsorption sites in holes when the hydrodynamic size of the polymer coil is larger than the hole, due to the size limiting effect. When the hydrodynamic size of the polymer coil is smaller than that of the holes, no difference in polymer adsorption was observed between raspberry-like and strawberry-like colloids. This study provides a strategy for regulating polymer adsorption on colloidal particles by adjusting the fine structures on the surface, which may be advantageous when limited chemical compositions are allowed. For example, protein adsorption on colloidal drugs may be found to be significantly reduced when colloids with surface holes are used.