Molecular motor-driven filament transport across three-dimensional, polymeric micro-junctions

Abstract

Molecular motor-driven filament systems have been extensively explored for biomedical and nanotechnological applications such as lab-on-chip molecular detection or network-based biocomputation. In these applications, filament transport conventionally occurs in two dimensions (2D), often guided along open, topographically and/or chemically structured channels which are coated by molecular motors. However, at crossing points of different channels the filament direction is less well determined and, though crucial to many applications, reliable guiding across the junction can often not be guaranteed. We here present a three-dimensional (3D) approach that eliminates the possibility for filaments to take wrong turns at junctions by spatially separating the channels crossing each other. Specifically, 3D junctions with tunnels and overpasses were manufactured on glass substrates by two-photon polymerization, a 3D fabrication technology where a tightly focused, femtosecond-pulsed laser is scanned in a layer-to-layer fashion across a photo-polymerizable inorganic–organic hybrid polymer (ORMOCER®) with µm resolution. Solidification of the polymer was confined to the focal volume, enabling the manufacturing of arbitrary 3D microstructures according to computer-aided design data. Successful realization of the 3D junction design was verified by optical and electron microscopy. Most importantly, we demonstrated the reliable transport of filaments, namely microtubules propelled by kinesin-1 motors, across these 3D junctions without junction errors. Our results open up new possibilities for 3D functional elements in biomolecular transport systems, in particular their implementation in biocomputational networks.

Nanolithographic Fabrication Technologies for Network-Based Biocomputation Devices

“…Refs. [ 19 , 20 , 21 ]). The actin-myosin system, using the motor protein myosin-II, which is a fast motor that is readily available from skeletal muscle to propel cytoskeletal actin filaments as the motile agents (cf.…”

Solving the 3‐Satisfiability Problem Using Network‐Based Biocomputation

“…To avoid a majority of filaments crossing the network making errors, the error rate at pass junctions needs to be below 0.07%, [15] a factor of 4 better than the best error rate reported for an NBC calculation so far [15] and achievable with error-free 3D junctions. [32] To ensure that a sufficient number of agents explore this network, %50 000 actin filaments are required, [14,33] which corresponds to %5 Â 10 À10 mg actin, an amount that is available at a very low cost. Third, agents need to be detected efficiently at exits, for example, using electrical/ optical sensors.…”

Solving Exact Cover Instances with Molecular-Motor-Powered Network-Based Biocomputation

“…(ii) Actin filaments will require the redesign of pass junctions in order to reduce the junction errors. This can be realized by narrower channels or the integration of 3D pass junction geometries with bridges and tunnels , that would eliminate pass-junction errors altogether. Despite our significant progress, it is obvious that NBC still has a long way to go if it is to compete with electronic computers that have had a headstart of decades’ (and billions of dollars) worth of research and development.…”