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

## TL;DR

This paper explores new surface treatments for myosin-based nanodevices, showing that vapor-phase silanization can effectively support actin filament motion.

## Contribution

A low-cost gas-phase silanization method is introduced for creating compatible surfaces for actomyosin nanodevices.

## Key findings

- FOTCS-functionalized surfaces achieved the highest sliding velocity of actin filaments (3.9 ± 1.2 μm/s).
- Gas-phase silanization using a commercial oven is a promising, low-cost method for surface functionalization.
- Microchannel patterning allowed confinement of actin filament motion to specific regions.

## Abstract

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.