Cells use molecular nanomachines, such as enzymes and motor proteins, to perform work and actively control the organization of matter within them. In this context, microtubules—filamentous structures made of tubulin proteins, which are part of the cellular cytoskeleton—serve as tracks for the transport and organization of components within cells. Motor proteins, such as kinesins and dyneins, move along microtubules, transporting molecules in different directions: kinesins move cargo from the center of the cell toward the membrane, whereas dyneins move it in the opposite direction. These proteins use the chemical energy of ATP to power their movement.
These ATP-dependent processes are known as active assembly, and they allow the generation of structures and complex transformations that do not occur through conventional self-assembly. Understanding and reproducing active assembly represents an important challenge for nanoscience, as it could enable the fabrication of materials with high levels of organization and dynamic responses.
A team of researchers in Japan developed a strategy for fabricating molecular materials using one of these biomolecular nanomachines. They attached DNA strands to microtubules and increased the length of the strands using the enzyme DNA polymerase, which is responsible for replicating genetic material. They then placed the microtubules in a chamber on whose surface they anchored kinesins.
Using fluorescence microscopy, they observed that adding an ATP-containing solution induced the microtubules to move, causing the long DNA strands attached to them to stretch and intertwine, forming a two-dimensional network within a few minutes. Finally, they determined that the concentration of microtubules and the duration of the DNA synthesis altered the connectivity and complexity of the two-dimensional network.
The DNA–microtubule system provides a model for studying how forces generated by molecular motors can control the formation, connectivity, and organization of networks. Moreover, DNA sequences can be designed to program the interactions and connectivity of the network. This work proposes a strategy for fabricating biomaterials using active molecular nanomachines, paving the way for the development of bioinspired materials with adaptive and potentially self-healing properties.
For further information go to:
