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Thermoresponsive PEG-based polymer layers

Surface characterization with AFM force measurements
: Kessel, S.; Schmidt, S.; Müller, R.; Wischerhoff, E.; Laschewsky, A.; Lutz, J.-F.; Uhlig, K.; Lankenau, A.; Duschl, C.; Fery, A.


Langmuir. The ACS journal of surfaces and colloids 26 (2010), Nr.5, S.3462-3467
ISSN: 0743-7463
ISSN: 1520-5827
Fraunhofer IAP ()
Fraunhofer IBMT ()

Thermoresponsive polymer-coated surfaces based on poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oliog(ethylene glycol) methacrylate) [P(MEO(2)MA-co-OEGMA)] allow switching between cell attachment and detachment. Here, we investigate the temperature-dependent surface interactions between the polymer coating and a colloidal probe in an aqueous medium by means of atomic force microscopy (AFM) force-distance measurements. The analysis of the adhesion forces from AFM retraction curves indentifies two kinds of regimes for the copolymer at temperatures below and above the lower critical solution temperature (LCST). Whereas at 25 degrees C the surface interactions with the polymer in the swollen state are dominated by repulsive forces, at 37 degrees C the surface interactions switch to attractive forces and a stronger adhesion is detected by AFM. Running several healing/cooling cycles repeatedly shows that switching the surface properties provides reproducible adhesion force values. Time-dependent measurements give insight into the switching kinetics, demonstrating that the cell response is coupled to the polymer kinetics but probably limited by the cellular rearrangements.