Focal adhesion development in cells adherent to surface bound fibronectin presented as 200, 500, or 1000 nm diameter circular patches or as homogeneous controls is studied by fluorescence and scanning electron microscopy. Fundamental cellular processes such as adhesion, spreading, focal adhesion and stress fiber formation are shown to be dependent on the spatial distribution of ligands at this scale. Large area samples enable the study of whole cell populations and opens for new potential applications.

Surface-mediated drug delivery is a recent concept, where active surface coatings are employed to deliver therapeutic cargo to cells. Herein, we explore the potential of liposomes embedded in polydopamine (PDA) coatings to serve as drug deposits stored on planar substrates. We quantify the PDA growth rate on glass by XPS and show that PDA coatings support myoblast adherence and proliferation. Further, PDA capping layers were deposited on glass substrates precoated with poly(L-lysine) and zwitterionic liposomes. Already thin PDA capping layers render liposome coated surfaces cell adhesive. We experimentally show for the first time, the internalization of a model hydrophobic cargo, that is, fluorescent lipids embedded within the lipid bilayer of liposomes by the cells from the surface. This is evident from the fluorescence exhibited by the cells grown on PDA coatings containing fluorescently labeled liposomes, with the highest fluorescent intensity found in the close proximity of the cell nuclei. The cargo uptake efficiency depends on the thickness of the PDA capping layer and the cell residence time on the coated substrates. Taken together, we demonstrate the first step toward the establishment of a versatile approach using liposomal drug deposits in polymer thin films for surface-mediated drug delivery.

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The effects of protein type and pattern size on cell adhesion, spreading, and focal adhesion development are studied. Fibronectin and vitronectin patterns from 0.1 to 3 μm produced by colloidal lithography reveal important differences in how cells adhere to and bridge focal adhesions across protein nanopatterns versus micropatterns. Vinculin and zyxin in focal adhesions but not integrins are seen to bridge ligand gaps. Differences in protein mechanical properties are implicated as important factors in focal adhesion development.

The potential of embryonic stem (ES) cells for both self-renewal and differentiation into cells of all three germ layers has generated immense interest in utilizing these cells for tissue engineering or cell-based therapies. However, the ability to culture undifferentiated ES cells without the use of feeder cells as well as means to obtain homogeneous, differentiated cell populations devoid of residual pluripotent ES cells still remain major challenges. Here we have applied murine ES cells to topographically microstructured surface libraries, BioSurface Structure Arrays (BSSA), and investigated whether these could be used to (i) identify topographically microstructured growth supports alleviating the need for feeder cells for expansion of undifferentiated ES cells and (ii) identify specific types of microstructures enforcing differentiation of ES cells. The BSSA surfaces arrays consisted of 504 different topographical microstructures each located in a tester field of 3 x 3 mm. The murine ES cell lines CJ7 and KH2 were seeded upon the BSSA libraries and specific topographical structures facilitating either undifferentiated ES cell growth or enhancing spreading indicative of differentiation of the ES cells were identified. Secondly serial passage of undifferentiated CJ7 ES cells on selected microstructures, identified in the screening of these BSSA libraries, showed that these cells had retained germ-line potential. These results indicate that one specific type of topographical surface microstructures, identified by the BSSA technology, can substitute for feeder cells and that another subset may be used to eliminate undifferentiated ES cells from a population of differentiated ES cells.