Tuning surface micropattern features using a shape memory functional polymer

Abstract

Living cells can alter their shapes and functions in response to physical cues at the cell–substrate interface, and consequently the temporal variations of the substrate surface are thought to be very important in governing cell behaviors. In this study, a thermally-activated shape memory function was employed to tune the dynamic change of the surface topography features on a polymer nanocomposite substrate. The polymer nanocomposite is composed of chemically cross-linked poly(ε-caprolactone) with allyl alcohol and Fe₃O₄ nanoparticles. The regular arrays of surface micropillar patterns were fabricated through thermal embossing micro-imprint lithography. They exhibited excellent shape memory performance with a recovery from a temporary shape at 34 °C to a permanent shape at 41 °C. The static and the dynamic surface micropillars as well as a smooth flat surface were used to study the behaviors of rat bone marrow mesenchymal stem cells. During this process, the surface micropillars switched from a temporal zero degree overwhelmed shape at 32 °C gradually to a permanent 90 degree standing shape at 41 °C due to the shape memory recovery. The results showed that the dynamic changes of the surface topography transition and the resultant force could effectively regulate cell adhesion, spread and alignment compared to the static surface micropillars and the smooth flat surface.