Cytoskeletal transition in patterned cells correlates with interfacial energy model.

A cell's morphology is intricately regulated by microenvironmental cues and intracellular feedback signals. Besides biochemical factors, cell fate can be influenced by the mechanics and geometry of the surrounding matrix. The latter point was addressed herein, by studying cell adhesion on two-dimensional micropatterns. Endothelial cells were grown on maleic acid copolymer surfaces structured with stripes of fibronectin by microcontact printing. Experiments showed a biphasic behaviour of actin stress fibre spacing in dependence on the stripe width with a critical size of approx. 15 µm. In a concurrent modelling effort, cells on stripes were simulated as droplet-like structures, including variations of interfacial energy, total volume and dimensions of the nucleus. A biphasic behaviour with regard to cell morphology and area was found, triggered by the minimum of interfacial energy, with the phase transition occurring at a critical stripe width close to the critical stripe width found in the cell experiment. The correlation of experiment and simulation suggests a possible mechanism of the cytoskeletal rearrangements based on interfacial energy arguments.

A new approach to biofunctionalisation and micropatterning of multi-well plates.

Biomolecule attachment and lateral micropatterning of biomolecular layers are essential techniques to provide in advanced biochemical and cell culture assays. For that purpose, we introduced a versatile, simple and robust method to functionalise standard polystyrene well plates. Free amino groups were generated on the polystyrene surface by low pressure ammonia plasma treatment. Subsequently, thin films of different maleic anhydride copolymers were covalently attached to the surfaces. The distinct physicochemical properties of the coupled maleic anhydride copolymers provided a broad range of possible attachment schemes of proteins and polysaccharides. Micrometer-sized lateral patterns of these functional coatings were created by plasma etching through silicon masks and subsequent chemical conversion of the etched areas using poly(ethylene glycol). The approach facilitates a wide variety of cell culture experiments allowing a combination of biomolecule coupling and micropatterning within the multi-well plate technology.