There is currently great interest in material science to mimic cellular microenvironments with controlled bioactive features and biomolecule presentation at the nanometer length scale. Target cells exposed to those 2- or 3D-substrates are stimulated to manifest a variety of cellular functions like cell adhesion, migration and differentiation.
Based on micellar nanolithography, we developed an experimental setup to present single biomolecules on a 2D-nanoarray over large areas on cell-adhesive or cell-repellent substrates. The spacing between biomolecules can be adjusted to 30-250 nm. To mimic a more complex cellular micro-environment with cell-cell contacts as well as cell-extracellular matrix (ECM) contacts, we used biomolecules from different cell adhesion molecule families, like cadherins, immunglobulin-superfamily, integrins and laminins. Via a Ni2+- nitrilo triacetic acid (NTA) system, the amount and the orientation of proteins is chemically controlled such that it resembles the native in vivo settings in the cellular microenvironment. By using poly-l-lysine-grafted-polyethylene glycol (PLL-g-PEG) molecules, we generated 2D-protein-nanoarrays with a cell repellent background matrix. After modification of this matrix we incorporated small bioactive peptides to create a microenvironment which allows cell adhesion. These approaches resulted in substrates with specific presentation of biomolecules to mimic cell-cell contacts and cell-ECM interactions simultaneously.
With these substrates we investigated primary fibroblast and neuronal cell adhesion mediated by different biomolecules and with different nanometer spacing. We quantified neurite outgrowth of dorsal root ganglion (DRG) neurons as a differentiation paradigm on nanostructured substrates. Gold nanoparticles were functionalized with peptides, containing the arginine-glycine-aspartic acid (RGD) motif, an integrin activation sequence. Cell adhesion as well as differentiation showed a dependency on the nanometer length scale and on the presented biomolecules.