Nanomotors

Nanomotors are nanoscale devices that convert energy into mechanical motion, enabling directed movement in fluids at the nanometer scale. They are studied as synthetic systems and as biohybrid constructs that combine artificial components with natural motors or cells. The goal is to achieve controllable propulsion and navigation in environments where viscous forces dominate.

Propulsion in nanomotors arises from several mechanisms. Catalytic motors use chemical reactions on their surfaces to create thrust, often through self-electrokinetic effects or by generating local gas bubbles. Magnetic motors rely on externally applied magnetic fields to steer and propel magnetizable components. Light-driven motors convert optical energy into motion via localized heating or photocatalytic reactions. Acoustic or ultrasound-driven motors use sound waves to induce movement. Enzyme-powered and biohybrid motors employ biological catalysts or cellular machinery to enable motion in physiological fluids.

Common implementations include catalytic nanorods or nanoparticles that decompose fuels such as hydrogen peroxide, magnetically steerable nanostructures, and optically or acoustically actuated designs. Enzyme-powered variants use biological catalysts to harvest chemical energy from biomolecules. The diversity of approaches reflects efforts to balance speed, controllability, biocompatibility, and compatibility with complex environments.

Applications of nanomotors span targeted drug delivery, precision biosensing, microfluidic manipulation, and environmental remediation. In biomedical contexts, they offer potential for site-specific therapy, imaging enhancement, and responsive diagnostic tools. In research settings, they serve as models to study propulsion at the nanoscale and to develop integrated lab-on-a-chip systems.

Challenges remain, including achieving reliable and selective navigation, ensuring biocompatibility and safety in vivo, scaling up fabrication, and integrating motors with control systems. Ongoing work seeks to improve efficiency, targeting accuracy, and integration with broader nanorobotics and nanomedicine initiatives.