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

Zwitterionic materials are now widely used to fabricate various functionalized surfaces for biomedical applications due to their excellent non-fouling properties. As 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). However, there are still few reports about choline phosphate, and to the best of our knowledge, a direct comparative study between choline phosphate and conventional zwitterionic materials has not been reported to date. To further investigate the properties of choline phosphate, a comparative study was conducted and the widely-reported zwitterionic phosphorylcholine, which has the same chemical component but opposite charge orientation with choline phosphate, was employed as a control. 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. The result shows that CP-functionalized surfaces exhibit almost equivalent amounts of adsorbed proteins to that of PC, but they are more beneficial to cells initial adhesion and further spreading in serum-free medium, indicating that CP has a promising prospect of application in tissue engineering.