Resisting Protein but Promoting Cell Adhesion by Choline Phosphate: A Comparative Study with Phosphorylcholine

Zwitterionic materials are now widely used to fabricate various functionalized surfaces for biomedical applications due to their excellent non-fouling properties. However, a newly-discovered zwitterionic material, choline phosphate (CP), was reported to be cell-adhesive, which makes it different from traditional non-fouling zwitterionic materials such as sulfobetaine, carboxybetaine and phosphorylcholine (PC). To further investigate the properties of CP, a comparative study was conducted and the widely-reported zwitterionic PC was employed as a control which has the same chemical component but opposite orientation of charged groups with CP. For this purpose, CP and PC-functionalized surfaces were prepared by surface-initiated atom transfer radical polymerization (Si-ATRP), and their non-fouling properties were probed by protein adsorption and eukaryotic cell adhesion measurement. Results showed that CP-functionalized surfaces exhibited almost equivalent amounts of adsorbed proteins to that of PC, but they were more beneficial to cells initial adhesion and further spreading in serum-free medium, indicating that CP had a promising prospect of application in tissue engineering.