Virus particles are captured and transported using kinesin‐driven, antibody‐functionalized microtubules. The functionalization was achieved through covalent crosslinking, which consequently enhanced the microtubule stability. The capture and transport of the virus particles was subsequently demonstrated in gliding motility assays in which antibody‐coated microtubules functioned as capture elements, and antibody‐coated microspheres served as fluorescent reporters (see Figure).

Recently, kinesin biomolecular motors and microtubules filaments (MTs) were used to transport metal and semiconductor nanoparticles with the long-term goal of exploiting this active transport system to dynamically assemble nanostructured materials. In some cases, however, the presence of nanoparticle cargo on MTs was shown to inhibit transport by interfering with kinesin-MT interactions. The primary objectives of this work were (1) to determine what factors affect the ability of kinesin and MTs to transport nanoparticle cargo, and (2) to establish a functional parameter space in which kinesin and MTs can support unimpeded transport of nanoparticles and materials. Of the factors evaluated, nanoparticle density on a given MT was the most significant factor affecting kinesin-based transport of nanoparticles. The density of particles was controlled by limiting the number of available linkage sites (i.e., biotinylated tubulin), and/or the relative concentration of nanoparticles in solution. Nanoparticle size was also a significant factor affecting transport, and attributed to the ability of particles < 40 nm in diameter to bind to the "underside" of the MT, and block kinesin transport. Overall, a generalized method of assembling and transporting a range of nanoparticle cargo using kinesin and MTs was established.

Thermodynamic relaxation can generate complex nanostructured materials via self-assembly; these structures, however, are ultimately limited by chemical equilibria and diffusional transport processes. [1] In contrast, living systems use a concerted combination of thermodynamic and energydissipating processes to remove these functional limitations, and generate complex, structured materials with a wide range of adaptive and emergent behaviors. An underlying principle of such systems involves the dynamic self-assembly of materials, which occurs outside of thermodynamic equilibrium, requires a source of energy, and bridges multiple length scales. [2][3][4] Analogous principles have been applied to assemble a broad range of artificial ''dissipative'' structures [5] through electrorheological, [6] magnetohydrodynamic, [7] electrohydrodynamic, [8] and magnetorheological, [9] interactions that induce spatiotemporal ordering. Efforts to understand these effects have led to significant insights into fundamental nonequilibrium physics.[10] While these approaches expand the practical range of materials, they rely on programmed or user-defined stimuli to drive the assemblies out of equilibrium. The next major step in developing materials assemblies will involve selfregulating systems that define the dynamic assembly and adaptive behavior of materials. Such feedback-regulated systems will extend the functional nature of nanostructured materials to include revolutionary behaviors (e.g., adaptive reconfiguration and self-healing), currently unattainable by conventional self-assembly methods.There are few examples of dynamic self-assembly in which the energy component is intrinsic to the system, as opposed to externally applied (e.g., electromagnetic fields). One system involves the dynamic assembly of nanospools [11,12] and nanocomposite rings [13] wherein assembly is achieved through a stochastic interaction of energy-dissipation and thermodynamic processes. One remarkable characteristic of both structures is the significant energy (i.e., >10 5 kT) that is required for their formation, which is based on the relatively high bending rigidity of the microtubules. [11] This energy input is cooperatively supplied through the hydrolysis of ATP by kinesin (energy dissipation) and the formation of multiple biotin-streptavidin bonds (thermodynamic). In addition, the nanospools display a highly nonequilibrium existence in which the unzipping of biotin-streptavidin bonds by kinesin motor leads to the spontaneous unspooling for the structures.[11] A unique aspect of the nanocomposite rings concerns the ability to assemble quantum dots across multiple length scales. The microtubules in these structures serve as a nanoscale scaffold for assembling the quantum dots; the quantum dot-laden microtubules subsequently self-organize into microscale, optically active structures. [13] While the properties of these nonequilibrium structures have been described, the mechanism of their formation is unknown and may provide valuable insight with respect t...