Effects of polymer topology on biointeractions of polymer brushes: Comparison of cyclic and linear polymers

Cyclic polymers, having no chain ends, are in contrast to their linear counterparts with respect to topology and related properties. While the behavior of cyclic polymers in solution is well investigated, there is little information on the effects of cyclic chain topology on surfaces grafted with these polymers. In particular, the effects of topology on the interactions of such surfaces with biological systems are unknown. In this work, we prepared gold surfaces modified with either cyclic or linear polystyrene (CPS, LPS) using a grafting-to strategy, and used these surfaces to investigate the effects of chain topology on their biointerfacial interactions. It was shown that compared to LPS with similar molecular weight, the smaller hydrodynamic radius of CPS leads to brushes of higher chain density, and that the higher chain density facilitates the adsorption of larger proteins but suppresses the adsorption of smaller ones. However, no significant differences in bacterial attachment or mammalian cell proliferation between CPS and LPS brushes were found, indicating that topological effects are absent for the larger entities.