title: Control of Cell Attachment and Spreading on Poly(acrylamide) Brushes with Varied Grafting Density.
abstract: To achieve spatial control of fibroblast cell attachment and spreading on a biocompatible polymer coating, the effect of poly(acrylamide) (PAAm) brushes with varied grafting density was investigated. The synthesis of the brushes was performed by surface-initiated atom transfer radical polymerization (SI-ATRP). Gold substrates were modified with binary self-assembled monolayers (SAMs) of an initiator and 16-mercaptohexadecanoic acid (MHDA) as an "inert" thiol to initiate the ATRP of AAm. By using different mixtures for the binary SAMs, a series of polymer brushes with varied grafting densities were prepared. The fractional coverage of surface bound initiator was determined by grazing incidence Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and contact angle measurements. A linear relationship between the Br/S ratio determined by XPS and ToF-SIMS versus the fraction of initiator on the surface determined by water contact angle measurements was observed. The varied initiation concentration on the gold substrates yielded PAAm brushes with different thicknesses, indicating a transition from mushroom to brush regimes with increasing grafting density. Thereby we achieved exquisite control of the degree of cell adhesion. Cell attachment experiments with NIH 3T3 fibroblast cells revealed cell spreading on PAAm brushes with low grafting densities (initiator fractional coverage <0.2) as well as a complete passivation by polymer brushes with higher grafting densities.
authors.affiliation: Physical Chemistry I, Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany.
authors.forename: Inga
authors.initials: I
authors.lastname: Lilge
authors.affiliation: Physical Chemistry I, Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Schönherr
mesh_terms: D000180:Acrylic Resins / Q000138:chemical synthesis* / Q000494:pharmacology; D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002452:Cell Count; D049109:Cell Proliferation / Q000187:drug effects; D006046:Gold / Q000737:chemistry* / Q000494:pharmacology; D051379:Mice; D041681:NIH 3T3 Cells; D010169:Palmitic Acids / Q000737:chemistry; D058105:Polymerization; D013329:Structure-Activity Relationship; D013499:Surface Properties; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D001672:Biocompatible Materials; D006046:Gold; D010169:Palmitic Acids; D000099166:Polyacrylamides; C450319:16-mercaptohexadecanoic acid