Dynamic display of biomolecular patterns through an elastic creasing instability of stimuli-responsive hydrogels.

Surfaces with physicochemical properties that can be modulated using external stimuli offer great promise for designing responsive or adaptive materials. Here, we describe biocompatible dynamic scaffolds based on thin hydrogel coatings that reversibly hide and display surface chemical patterns in response to temperature changes. At room temperature, the gel absorbs water, triggering an elastic creasing instability that sequesters functionalized regions within tight folds in the surface. Deswelling at approximately 37 degrees C causes the gel surface to unfold, thereby regenerating the biomolecular patterns. Crease positions are directed by topographic features on the underlying substrate, and are translated into two-dimensional micrometre-scale surface chemical patterns through selective deposition of biochemically functionalized polyelectrolytes. We demonstrate specific applications of these dynamic scaffolds--selective capture, sequestration and release of micrometre-sized beads, tunable activity of surface-immobilized enzymes and reversible encapsulation of adherent cells--which offer promise for incorporation within lab-on-a-chip devices or as dynamic substrates for cellular biology.