title: Temperature-controlled masking/unmasking of cell-adhesive cues with poly(ethylene glycol) methacrylate based brushes.
abstract: Thin, thermoresponsive polymer coatings that allow to reversibly modulate cell adhesion and detachment are attractive substrates for cell sheet engineering. Usually, this is accomplished by applying thin poly(N-isopropylacrylamide) (PNIPAM) coatings, which allow cell adhesion via nonspecific interactions above the collapse temperature (T(T)) of the surface-attached polymer and cell detachment upon cooling below T(T). This Article presents an alternative, thermoresponsive polymer platform that is based on 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) containing copolymer brushes prepared via surface-initiated atom transfer radical polymerization (SI-ATRP). These brushes are interesting as they gradually collapse and dehydrate upon increasing the temperature from 10 to 40 °C, yet resist nonspecific adhesion of cells over this entire temperature window. The MEO2MA based brushes presented here were modified via a two-step postpolymerization modification protocol to introduce cell-adhesive RGD containing peptide ligands. The possibility to reversibly control the swelling and collapse of these brush films by varying temperature allows to modulate the effectively available surface concentration of these cell-adhesive cues and thus provides a way to mask/unmask their biological activity. As a first proof of concept, this Article demonstrates that these MEO2MA brush copolymer films enable integrin-mediated adhesion of 3T3 fibroblasts at 37 °C and allow release of these cells by cooling to 23 °C. The use of cell-adhesive ligands, which can be thermoreversibly masked/unmasked, is attractive as it enables the use of serum-free cell culture conditions. This is advantageous since it avoids possible concerns regarding eventual toxicity and immunological side effects of serum proteins and also provides opportunities to select for particular cell types and for enhanced control over cell stimulation and differentiation.
authors.affiliation: Institut des Matériaux et Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, École Polytechnique Fédérale de Lausanne (EPFL) , Bâtiment MXD, Station 12, CH-1015 Lausanne, Switzerland.
authors.forename: Solenne
authors.initials: S
authors.lastname: Desseaux
authors.forename: Harm-Anton
authors.initials: HA
authors.lastname: Klok
mesh_terms: D016475:3T3 Cells; D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000737:chemistry; D008689:Methacrylates / Q000737:chemistry*; D051379:Mice; D011092:Polyethylene Glycols / Q000737:chemistry*; D058105:Polymerization; D011108:Polymers / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D008689:Methacrylates; D011108:Polymers; C524499:polyethylene glycol methacrylate; C539356:2-(2-methoxyethoxy)ethyl methacrylate; C052970:poly-N-isopropylacrylamide; D011092:Polyethylene Glycols