Formation of responsive hierarchical wrinkled patterns on hydrogel films via multi-step methodology

Smart Polymer Surfaces with Complex Wrinkled Patterns: Reversible, Non-Planar, Gradient, and Hierarchical Structures

This review summarizes the relevant developments in preparing wrinkled structures with variable characteristics. These include the formation of smart interfaces with reversible wrinkle formation, the construction of wrinkles in non-planar supports, or, more interestingly, the development of complex hierarchically structured wrinkled patterns. Smart wrinkled surfaces obtained using light-responsive, pH-responsive, temperature-responsive, and electromagnetic-responsive polymers are thoroughly described. These systems control the formation of wrinkles in particular surface positions and the reversible construction of planar-wrinkled surfaces. This know-how of non-planar substrates has been recently extended to other structures, thus forming wrinkled patterns on solid, hollow spheres, cylinders, and cylindrical tubes. Finally, this bibliographic analysis also presents some illustrative examples of the potential of wrinkle formation to create more complex patterns, including gradient structures and hierarchically multiscale-ordered wrinkles. The orientation and the wrinkle characteristics (amplitude and period) can also be modulated according to the requested application.

Biocompatible fluorinated wrinkled hydrogel films with antimicrobial activity

Surface-modified hydrogel films were designed to control the bacterial colonization on their surface and to promote cell proliferation through the gradual insertion of highly hydrophobic functional monomers. These hydrogel films were deposited via spin-coating technique, using muscovite mica as a substrate. These samples were then exposed to different external stimuli to produce wrinkled patterns. The relationship between the monomers which compose the hydrogel, was varied to alter the hydrophobic/hydrophilic balance of the final composite. Contact angle and confocal Raman spectroscopy measurements were carried out to characterize the surface and the bulk of the hydrogel film. Cell proliferation and antimicrobial tests were performed using premyoblastic murine cells (C2C12-GFP) and RAW 264.7 (ATCC® TIB-71) macrophagic cell lines, and also for bacteria strains, Staphylococcus aureus and Escherichia coli. The results indicate that the inclusion of the TFPMA produces an increase in cell proliferation, together with a decrease in living bacterial colonies after 48 h, both for Gram-positive or Gram-negative species.