Publications

Living organisms, from single cells to multicellular systems, are capable of moving as a response to local stimuli using swarming intelligence, a trait researchers aim to replicate in artificial systems. Common strategies observed in natural swarms include motility towards specific signals from the environment, communication among individual units, coordination and cooperation to achieve complex tasks. Inspired by these features, the focus in bioinspired motile nanosystems has shifted from studying individual units to exploring and controlling collective behaviours. Various propulsion mechanisms including magnetic, electric or acoustic fields, as well as onboard chemical reactions, have enabled artificial micromotor and nanomotor (MNM) swarms that can move collectively as a response to environmental inputs. The controlled navigation and improved tissue penetration of MNM swarms is promising within the biomedical field, including in the active transport of medical agents. Despite these exciting advances, artificial MNMs still fall short of the complexity and autonomy seen in biological systems. This Perspective explores the collective behaviour of biological swarms and bioinspired artificial self-propelled nanosystems. We discuss how swarming intelligence applied to synthetic active nanosystems enables swarms to perform various tasks. Finally, we discuss challenges, including material limitations, information storage, communication between swarms and prospects for intelligent swarming systems.

JTD Keywords: Acoustic propulsion, Behavior, Chemical communication, Chemotaxis, Drive, Mechanisms, Nanorod motors, Ph taxis, Powered nanomotors, Supramolecular nanomotors

Enzymatic nanomotors harvest kinetic energy through the catalysis of chemical fuels. When a drop containing nanomotors is placed in a fuel-rich environment, they assemble into ordered groups and exhibit intriguing collective behaviour akin to the bioconvection of aerobic microorganismal suspensions. This collective behaviour presents numerous advantages compared to individual nanomotors, including expanded coverage and prolonged propulsion duration. However, the physical mechanisms underlying the collective motion have yet to be fully elucidated. Our study investigates the formation of enzymatic swarms using experimental analysis and computational modelling. We show that the directional movement of enzymatic nanomotor swarms is due to their solutal buoyancy. We investigate various factors that impact the movement of nanomotor swarms, such as particle concentration, fuel concentration, fuel viscosity, and vertical confinement. We examine the effects of these factors on swarm self-organization to gain a deeper understanding. In addition, the urease catalysis reaction produces ammonia and carbon dioxide, accelerating the directional movement of active swarms in urea compared with passive ones in the same conditions. The numerical analysis agrees with the experimental findings. Our findings are crucial for the potential biomedical applications of enzymatic nanomotor swarms, ranging from enhanced diffusion in bio-fluids and targeted delivery to cancer therapy. Enzymatic nanomotors exhibit collective behaviour in fuel-rich environments, forming swarms with enhanced propulsion and coverage. This study investigates the factors affecting swarm movement, revealing that solutal buoyancy drives their motion, with potential biomedical applications like targeted drug delivery.

JTD Keywords: Ammonia, Behavior, Carbon dioxide, Catalysis, Computer simulation, Kinetics, Motion, Nanostructures, Powered nanomotors, Propulsion, Urease, Viscosity

Micro/nanomotors (MNMs) have evolved from single self-propelled entities to versatile systems capable of performing one or multiple biomedical tasks. When single MNMs self-assemble into coordinated swarms, either under external control or triggered by chemical reactions, they offer advantages that individual MNMs cannot achieve. These benefits include intelligent multitasking and adaptability to changes in the surrounding environment. Here, we provide our perspective on the evolution of MNMs, beginning with the development of enzymatic MNMs since the first theoretical model was proposed in 2005. These enzymatic MNMs hold immense promise in biomedicine due to their advantages in biocompatibility and fuel availability. Subsequently, we introduce the design and application of single motors in biomedicine, followed by the control of MNM swarms and their biomedical applications. In the end, we propose viable solutions for advancing the development of MNM swarms and anticipate valuable insights into the creation of more intelligent and controllable MNM swarms for biomedical applications.; Micro/nanomotor swarms propelled by diverse mechanisms.

JTD Keywords: Active particles, Actuation, Behaviors, Biocompatibility, Biomedical applications, Coordination reactions, Design and application, Diffusion, External control, Medical applications, Micromotors, Motion, Nanomotors, Powered nanomotors, Propulsion, Self-assemble, Surrounding environment, Theoretical modeling, Versatile system, Viable solutions