Actin-Based Molecular Motors for Cargo Transportation in Nanotechnology— Potentials and Challenges

Here, we review the use of actin-based motors, (myosins; e.g., the molecular motor of muscle) in nanotechnology. The review starts from the viewpoints of the molecular motors as being important devices responsible of cargo transportation in the cell and end in discussions about their employment in nanotechnological applications. First, we describe basic biophysics of the myosin motors with focus on their involvement in cargo transportation in the living cell, leading us over into a discussion about in vitro motility assays. These are biological test systems where the myosin-induced translocation of actin filaments is studied on an artificial surface outside the cell. Then follows a review about modified motility assays for production of ordered motion. Here, we discuss ours and others' work with regards to making micro- and nanostructured surfaces and channels where the position and direction of movement produced by molecular motors is controlled. In this section, we consider the role of the channel size in promoting unidirectional myosin-induced motion of actin filaments. Furthermore, we consider the usefulness of surface modifications, e.g., various silanization procedures in order to promote and hinder molecular motility, respectively. Particularly, we describe our latest test system being both morphologically and chemically nanostructured giving us unsurpassed possibilities to perform functional studies as well as extremely good spatio-temporal control. Then follows a section about nanotechnological cargo transportation systems based on the actomyosin motor system. For instance, we present results of attaching fluorescent quantum dots as cargoes to the actin filaments. In this section, we also discuss the possibilities of having cargo attachment and detachment being performed on demand. Finally, we consider the usefulness of molecular motors for lab-on-a-chip applications and the requirements for incorporating these motors in commercially viable devices. In this context, the significant potential of the actomyosin motor system to overcome traditional limitations of micro- and nanofluidics is stressed.