Final Report Summary - STOMAMOTOR (Stomatocyte Nanomotors: Programmed Supramolecular Architectures for Autonomous Movement)
Nano jet engines seeking out disease and administering drugs only to sick cells has always been a fascination for scientists in their effort to gain control over the movement at nanoscale and has been often associated with futuristic visions of building “tiny cars”, “aircrafts” or “submarines” as small as bacteria or “microscopic surgeons” able to reach infected organs and cure diseases. But why not let the motor build itself? We have recently reported the first assembly of supramolecular nanomotors from amphiphilic block copolymers. The small building blocks self-assemble into a vesicular structure polymersome, which upon change in the osmotic pressure is reengineered into bowl- shaped polymersomes (stomatocyte) with a small opening. We have reported novel methodologies for shape transformation that allowed for encapsulation within the bowl shape structure of active catalysts from nanoparticles to more delicate enzyme or even multiple enzymes. The movement of the nanomotor is driven by the fast discharge of jet gases (oxygen) through an outlet generating thrust by jet propulsion. The gases are produced during the catalytic decomposition of a fuel (hydrogen peroxide) inside the nanocavity where the active catalyst (motor) is entrapped. The speed of the nanomotors can be efficiently controlled even at very low concentrations of the fuel while the amount of fuel determines the prevalence of the two competing mechanisms: bubble propulsion or self-diffusionphoresis. Furthermore we have demonstrated the directional movement in a gradient of fuel of the self-assembled nanomotors, which is the first example of a soft supramolecular nano-meter scale motor capable to carry a drug as a cargo and control its movement and directionality by a chemotaxis mechanism. The structures were also designed to be responsive under external stimuli such as temperature or magnetic field, which would allow for greater control of the nanomotor assembly. Finally we have also demonstrated that we can manipulate these structures in magnetic fields to generate a supramolecular magnetic valve able to capture and release cargo under a magnetic field in a reversible and controlled manner. Currently, we are developing techniques of motor self-assembly that are more elegant than physical entrapment proposed in the ERC grant that allows for more controlled catalyst encapsulation, such as chemical modification. We are also interested in expanding the scope of the self- assembled catalytic nanomotors towards other supramolecular assemblies able to propel in biological fuels and at biological relevant concentrations. The ultimate aim is to develop a truly active targeting system for chemotherapeutics by assembling nanomotors that are able to carry cargo and direct their movement via chemotaxis.