Effects of Methacrylate-Based Thermoresponsive Polymer Brush Composition on Fibroblast Adhesion and Morphology.

Thermoresponsive polymers are being used increasingly in cell culture applications due to their temperature dependent surface properties. Poly(MEO(2)MA-co-OEGMA) (PMO) brushes offer tunable physical properties via variation in the copolymer ratio, but the effects of composition on cell-substrate interactions is unclear. To this end, a series of PMO brushes (0-8% OEGMA) was fabricated and L-929 fibroblast adhesion and morphology was quantified in the presence of serum (FBS) or after functionalization via the adsorption of fibronectin (FN) and vitronectin (VN). Quantification of the adsorption of model proteins, bovine serum albumin and FN, revealed that the extent of adsorption was correlated to the amount MEO(2)MA content, which represents the more hydrophobic component in PMO brushes. Cells exhibited delayed attachment and spreading on all PMO substrates in the presence of FBS. After 24 h, cell attachment was comparable; however, increased spreading was correlated with increased MEO(2)MA content. Adsorption of FN significantly increased initial cell attachment to all PMO surfaces after 2 h. This was not observed with VN; however, both FN and VN increased cell spreading/decreased cell circularity for all PMO substrates relative to FBS. Pure MEO(2)MA brushes with FN exhibited increased cell spreading/decreased cell circularity relative to other PMO substrates after 2 h, and elicited the highest cell density after 24 h. These results demonstrate that increased MEO(2)MA content in PMO substrates facilitates cell attachment and spreading, which can be further enhanced by adsorbing FN in the absence of other proteins.