Self‐Propelled Polymer‐Based Multilayer Nanorockets for Transportation and Drug Release

Abstract

There is a growing effort in the scientific community to design and fabricate versatile artificial nanomotors propelled by selfgenerated forces, because they have potential in the field of directed drug delivery, roving sensors, isolation and detection of targets, active biomimetic systems, and other emerging applications. [1] Inspired by the nanoscale linear biomotors (for example, kinesins), which can autonomously move in aqueous solution and are powered by spontaneous hydrolysis of biological energy units, substantial efforts towards the design of chemically powerful synthetic motors at the micro-and nanoscale have recently demonstrated the ability of converting chemical energy into autonomous motion based on a fuel solution (for example, aqueous hydrogen peroxide solution). [2][3][4] To explain the motion and energy transfer process in these chemically powered systems, several mechanisms, including bubble propulsion, [5] interfacial tension gradients, [6] self-electrophoresis, [7] self-diffusiophoresis, [8] osmotic propulsion, [9] ultrasound propulsion, [10] and polymerization reactions [11] were proposed.Among diverse synthetic microengines, chemically powered tubular micromotors prepared by the rolled-up technique and template electrosynthesis have displayed a high speed and the controllable directionality of the movement compared to bimetal nanorods or Janus microsphere motors. [12,13] These rocket-like microengines are capable of the pick-up, transportation, and release of various cargoes, including polymer particles, [14] nucleic acids, [15] cancer cells, [16] and bacteria. [17] However, they still have some inherent limitations, such as complex preparation technology, difficulty of surface modification, and poor biocompatibility or biodegradability. Moreover, it is required in many cases that synthetic motors can encapsulate, transport, and release targeted substances by themselves in an easy and controllable way and have good biocompatibility and biodegradability, particularly in both biomedical and environmental fields. Therefore, it still remains a challenge to develop new fabrication methods and expand the diversity of the building components.

Chemotactic Guidance of Synthetic Organic/Inorganic Payloads Functionalized Sperm Micromotors

“…[7][8][9][10] These synthetic motors are also able to carry payloads in high capacity and release them in a controlled manner. [11][12][13][14] In addition to synthetic micromotors driven by external fuel, researchers have also looked into inspiration from nature to design novel biomotors with unique biological functions. For instance, both bacteria and erythrocyte cells have been modified toward functional micromotors.…”

Tubular micromotors: from microjets to spermbots

“…Such nanoengines present an easy-tofunctionalize outer surface based on biodegradable natural polysaccharides and platinum nanoparticles assembled by layer-by-layer (LbL) techniques into the template pores of their inner surface (see Figure 4AIV). Their controlled movement was achieved by integrating iron oxide (Fe 3 O 4 ) nanoparticles, permitting their convenient motion towards HeLa cells and proving their capacity as a drug delivery system by using their outer layers for drug encapsulation [52].…”

Autonomous movement of a chemically powered vesicle

“…For the other route the propulsion rely on asymmetric chemical reactivity instead of asymmetric conformational dynamics. The most widely studied example of this type of motors are bimetallic nanorods 10,11 , Janus particles 12 , sphere dimer motors [13][14][15] , polymers 16 The above cited example of physically asymmetric selfproplled objects assume that the particle shape is unchanged during the motion. However, in reality many self-propelled objects may change their shape depending on the velocity, environment or interaction with other objects.…”