Polymer-based Nanomotors and Artificial Cells

A seminar by by Professor Jan Van Hest 

IDL Auditorium in WMG (map here).

 Compartmentalization is generally regarded as one of the key prerequisites for life. In living cells, not only the cell itself is a compartment, with its properties controlled by the semipermeable cell membrane, but also the organelles play a crucial role in protecting and controlling biological processes. To better understand the role of compartmentalization, there is a clear need for model systems that can be adapted in a highly controlled fashion, and in which life-like properties can be installed. Polymer-based compartments are robust and chemically versatile, and as such are a useful platform for the development of life-like compartments. In this lecture both nanomotors and artificial cell systems will be discussed. The nanomotors are composed of biodegradable amphiphilic block copolymers that self-assemble into vesicular structures. By introducing asymmetry in the structure and by functionalizing them with propelling units they can be converted into nanomotors For example, via a shape change process a bowl-shaped structure is obtained out of a spherical vesicle. Within the cavity of the bowl enzymes are loaded which provide the nanostructure with motility upon conversion of chemical energy into kinetic energy. These nanomotors are explored for biomedical applications, in particular photodynamic therapy

The synthetic cell platform is composed of a complex polymer coacervate, stabilized by a biodegradable block copolymer which creates a semi-permeable membrane. The coacervate structures resemble better the crowded environment observed in the cytoplasm than vesicular structures normally do. Cargo, such as enzymes, can be highly effectively loaded in the coacervates, based on complementary charge and affinity, e.g. by using Ni-NTA-His tag interactions. This allows protocell communication with this robust synthetic platform. Via this system we have been able to show that we can bring enzymes involved in cascade reactions closer to each other, facilitating the outcome of the process. We can controllably release proteins from the artificial cell, mimicking natural secretion, and we can incorporate multiple artificial organelles in the interior, thereby mimicking the architecture of a eukaryotic cell. Finally, we are able to incorporate life-like features such as motility in these structures, making this class of artificial cells a very versatile platform to study and mimic biological processes.