title: Nanostructured Biointerfaces: Nanoarchitectonics of Thermoresponsive Polymer Brushes Impact Protein Adsorption and Cell Adhesion.
abstract: Controlling the reversibility, quantity, and extent of biomolecule interaction at interfaces has a significant relevance for biomedical and biotechnological applications, because protein adsorption is always the first step when a solid surface gets in contact with a biological fluid. Polymer brushes, composed of end-tethered linear polymers with sufficient grafting density, are very promising to control and alter interactions with biological systems because of their unique structure and distinct collaborative response to environmental changes. We studied protein adsorption and cell adhesion at polymer brush substrates which consisted of poly(N-isopropylacrylamide) (PNIPAAm), having a lower critical solution temperature (LCST), to control bioadsorptive processes by changing the environmental temperature. Preparing the PNIPAAm brushes by the "grafting-to"-method two differently synthesized PNIPAAm polymers were used, at which one possessed an additional hydrophobic terminal headgroup. It is known that hydrophobic moieties can influence protein adsorption significantly. The films were comprehensively analyzed by in situ spectroscopic ellipsometry, contact angle measurements, streaming potential, and atomic force microscopy. Our study was mainly focused on the investigation of the fibrinogen (FGN) adsorption responsiveness both on homo polymer PNIPAAm brushes with and without the hydrophobic terminal functionalization, and further on binary brushes made of the polyelectrolyte poly(acrylic acid) (PAA) and one of the prior described two PNIPAAm species. The results show that the terminal hydrophobic modification of PNIPAAm has a considerable impact on wettability, LCST, and morphology of the homo and the binary brush systems, which consequently led to an alteration of FGN adsorption. By using binary PNIPAAm-PAA brushes with different composition it was possible to induce stimuli dependent FGN adsorption with a considerable amplified switching effect by introducing a hydrophobic terminal residue to PNIPAAm. Cell adhesion studies with human mesenchymal stem cells reflected the results of the FGN adsorption.
authors: ‡Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany.|§Faculty of Science, Department of Chemistry, Chair of Physical Chemistry of Polymeric Materials, The Technische Universität Dresden, Bergstrasse 66, 01069 Dresden, Germany.
authors: Evmorfia
authors: E
authors: Psarra
authors: ‡Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany.
authors: Ulla
authors: U
authors: König
authors: ⊥Department of Biocompatibility, Institute of Biomaterial Science HZG Teltow, Kantstrasse 55, 14513 Teltow, Germany.
authors: Yuichiro
authors: Y
authors: Ueda
authors: ‡Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany.
authors: Cornelia
authors: C
authors: Bellmann
authors: ‡Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany.
authors: Andreas
authors: A
authors: Janke
authors: ‡Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany.
authors: Eva
authors: E
authors: Bittrich
authors: ‡Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany.
authors: Klaus-J
authors: KJ
authors: Eichhorn
authors: ‡Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany.
authors: Petra
authors: P
authors: Uhlmann
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000327:Adsorption / Q000187:drug effects; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects*; D002478:Cells, Cultured; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D059630:Mesenchymal Stem Cells / Q000378:metabolism; D049329:Nanostructures / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D001672:Biocompatible Materials; C052970:poly-N-isopropylacrylamide; D005340:Fibrinogen
keywords: fibrinogen adsorption; grafting-to-method; nanomaterials; polymer brush; spectroscopic ellipsometry; stimuli response