title: Tuning cell adhesion on gradient poly(2-hydroxyethyl methacrylate)-grafted surfaces.
abstract: A simple yet versatile method was developed to prepare a low-density polymerization initiator gradient, which was combined with surface-initiated atom transfer radical polymerization (ATRP) to produce a well-defined poly(2-hydroxyethyl methacrylate) (HEMA) gradient substrate. A smooth variation in film thickness was measured across the gradient, ranging from 20 A to over 80 A, but we observed a nonmonotonic variation in water contact angle. Fits of X-ray reflectivity profiles suggested that at the low graft density end, the polymer chain structure was in a "mushroom" regime, while the polymer chains at high graft density were in a "brush" regime. It was found that the "mushroom" region of the gradient could be made adhesive to cells by adsorbing adhesion proteins, and cell adhesion could be tuned by controlling the density of the polymer grafts. Fibroblasts were seeded on gradients precoated with fibronectin to test cellular responses to this novel substrate, but it was found that cell adhesion did not follow the expected trend; instead, saturated cell adhesion and spreading was found at the low grafting density region.
authors.affiliation: Polymers Division and Biotechnology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Mei
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.forename: Chang
authors.initials: C
authors.lastname: Xu
authors.forename: Kurt J
authors.initials: KJ
authors.lastname: Langenbach
authors.forename: John T
authors.initials: JT
authors.lastname: Elliott
authors.forename: Bryan D
authors.initials: BD
authors.lastname: Vogt
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Beers
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Amis
authors.forename: Newell R
authors.initials: NR
authors.lastname: Washburn
mesh_terms: D000327:Adsorption; D000818:Animals; D002448:Cell Adhesion; D008689:Methacrylates / Q000737:chemistry*; D051379:Mice; D041681:NIH 3T3 Cells; D011108:Polymers / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry; D013499:Surface Properties
chemical_list: D008689:Methacrylates; D011108:Polymers; D011506:Proteins; C005044:hydroxyethyl methacrylate