Periodic block copolymer patterns for fundamental biological studies

Cells are embedded in a complex meshwork of biomolecules known as extracellular matrix (ECM), whose composition, mechanical properties and nanoscale organization determine the cellular fate. Understanding the role of each ECM component as well as their synergistic effect will allow to decipher and control numerous fundamental cellular processes as adhesion, differentiation, growth and motility [1]. So far, ECM mimicking substrates of different complexity have been developed using advanced techniques with various resolutions. Herein, we describe the utility of block copolymers (BC) in the formation of spatially controlled templates at the nanoscale by self-assembly. This approach offers a possibility to create nanopatterns over large surface areas [2]. Moreover, BC bearing specific/active groups can be chosen in order to further functionalize the assembled nanopattern. As an example, we used polystyrene-block-poly-2-vinylpyridine (PS-b-2PVP) diblock copolymer because of the possibility of following functionalization through electrostatic interactions via the PVP block.[2] The nanoscale patterns of PS-b-2PVP were formed upon structural reorganization of the BCs induced by solvent vapor annealing (SVA). We generated different patterns by changing the annealing time, annealing solvent or temperature. The created patterns were further functionalized with hyaluronic acid (HA) –glycosaminoglycan (GAG) that is a major ECM component. HA interacts with structural and signaling proteins (e.g. CD44) via multiple interactions. Thus, the pattern and density of HA influence significantly its bioactivity as previously demonstrated by us and others [3, 4]. We therefore suggest that the developed nanopatterns can be a useful tool in revealing the importance of the HA density and pattern in a range of fundamental biological studies.