Controlling the Crystallinity of Thermoresponsive Poly(2-oxazoline)-Based Nanolayers to Cell Adhesion and Detachment.

Semicrystalline, thermoresponsive poly(2-isopropyl-2-oxazoline) (PIPOx) layers covalently bonded to glass or silica wafers were obtained via the surface-termination of the living polymer chains. Polymer solutions in acetonitrile were exposed to 50 °C for various time periods and were poured onto the functionalized solid wafers. Fibrillar crystallites formed in polymerization solutions settled down onto the wafers next to the amorphous polymer. The amount of crystallites adsorbed on thermoresponsive polymer layers depended on the annealing time of the PIPOx solution. The wettability of PIPOx layers decreased with the increasing amount of crystallites. The higher content of crystallites weakened the temperature response of the layer, as evidenced by the philicity and thickness measurements. Semicrystalline thermoresponsive PIPOx layers were used as biomaterials for human dermal fibroblasts (HDFs) culture and detachment. The presence of crystallites on the PIPOx layers promoted the proliferation of HDFs. Changes in the physicochemical properties of the layer, caused by the temperature response of the polymer, led to the change in the cells shape from a spindle-like to an ellipsoidal shape, which resulted in their detachment. A supporting membrane was used to assist the detachment of the cells from PIPOx biosurfaces and to prevent the rolling of the sheet.