Temperature-Assisted Gas-phase Silanization Using Different Silanes for Actomyosin-Based Nanodevices

Motor proteins drive motion in living systems. Myosin motors adsorbed on a surface propel actin filaments by hydrolyzing ATP. This makes them interesting systems for applications in nanotechnology, e.g. as sensors, for transporting molecular cargo or driving other forms of molecular motion. However, their effective functioning requires the proper combination of materials with adequate surface chemistry and hydrophobic properties. Here, we investigate a set of materials systems used as substrates and analyze their compatibility with the actomyosin system. As a reference, we used glass slides coated with trimethylchlorosilane (TMCS) where coating is performed in liquid phase, since this is a commonly used approach. We then explored an alternative vapor phase deposition method to coat glass slides with various silane compounds: in addition to TMCS, we also used perfluoro-octyltrichlorosilane (FOTCS) and perfluoro-dodecyltrichlorosilane (FDDTCS). In vitro motility assays (IVMAs), where surface-adsorbed myosin motor fragments propel actin filaments, were then used to measure the sliding velocity on the different surfaces. Filaments propelled on FOTCS-functionalized surfaces by chemical vapor deposition exhibited the highest average sliding velocity (3.9 ± 1.2 μm/s; mean ± SD) and retained a high fraction of motile actin filaments (87%), comparable to TMCS-functionalized surfaces (3.3 ± 0.4 μm/s, 90% motile). In addition, we also used a UV-curable polymer as active substrate material, which we have successfully treated to either promote or inhibit motor adsorption and therefore motility. We have evaluated the hydrophobic characteristics and the roughness of the different functionalized surfaces. In addition, we patterned microchannels with physical and chemical contrast, to confine the motor adsorption and consequently motion of the myosin- driven actin filaments to the patterned microchannel bottoms. This gas-phase deposition technique uses just a low cost commercial oven and offers a promising method for tailoring the surface properties of various materials, paving the way for standardizing and advancing the application of myosin-propelled actin filaments in nanotechnology and microdevices.