A facile approach to a highly bio-active interface material is reported. XPS reveals that polar entities exist at the interface between PPAam and PPAac nanolayers. They induce strong dipolar orientation polarizability and cause the redistribution of charges, which results in a remarkable increase of polar surface energy and hydrophilicity of the multistack bipolar films. In particular bipolar films with amine groups on their outermost surface show strongly enhanced cellular mobility. The attachment, adhesion, proliferation, migration, and coverage of ECs are significantly enhanced on such films. They are therefore promising as vascular implant materials, and could have applications as coating materials for tissue engineering.
An intentional and defined grafting of the material surface with multiple positive/negative charges produced by functional groups is desired for biomedical applications. In this work, multistacked organic bipolar films containing alternating nano‐layers of plasma polymerized acrylic acid (PPAac) and plasma polymerized allylamine (PPAam) are investigated in order to prepare highly polarized surfaces with positive/negative charges. Two kinds of composite films fabricated according to different depositing sequences and with –COOH or –NH2 functional groups onto their outermost surfaces are prepared. The results of ATR‐FTIR and XPS demonstrate that a significant number of COO– and –NH 3+ polar entities, generated from the interaction of PPAac and PPAam films, are present in these multistacked organic bipolar films. Furthermore, the remarkably increased polar surface energy of these composite films, compared with pure PPAac and PPAam films, reveals that the presence of the COO– and NH 3+ polar entities induces strong dipole orientation polarizability, and results in the redistribution of charges. The results suggest that the surface with highly polarized –COOH and –NH2 groups have high surface charges and chemical reactivity. These surfaces show promising applications for biomolecules binding and cell growth.
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