Nanoscale active matter matters: Challenges and opportunities for self-propelled nanomotors

Progress in nanotechnology has enabled the synthesis of active particles that can harness chemical energy and translate it into useful work. Catalytic self-propelled motors have implications for understanding out of-equilibrium systems and have potential applications in active transport at the nanoscale, where they can be used as motors and pumps. Although much research has been done on micron-sized motors, progress in catalytic nanomotors of sub 100 nm is still in its infancy. These nanosized motors are of great importance for future molecular transport at the cellular level because they operate at length scales at which protein motors work. This opinion article focusses on recent advances in the synthesis of catalytic nanomotors and experimental strategies to measure their self-propulsion, which differ from that of micromotors. Enzymatic and metallic nanomotors are surveyed, together with various theoretical models for self-propulsion. Solutions to current challenges are proposed, which include a chemical synthesis approach, new characterisation of motor activity and potential uses of nanomotors in nanomedicine. (C) 2018 Elsevier Ltd. All rights reserved.