Nanomotors: Where Are They Now?

First introduced in 2004, nanomotors have steadily advanced from a scientific curiosity to a practical technology with wide-ranging applications. This article explores the key developments, recent innovations, and major uses of nanomotors today.

A Brief Overview of Nanomotors

Nanomotors are nanoscale devices that can efficiently convert different forms of energy into mechanical movement, allowing them to self-propel through liquids. Their ability to move autonomously and release substances in a liquid environment makes them especially valuable in biomedicine, environmental remediation, sensing technologies, and manufacturing.¹

Nanomotors are primarily driven by bubble propulsion, self-electrophoresis, and self-diffusiophoresis. Scientists have made significant advances in the last twenty years, overcoming fabrication challenges at the nanoscale and refining motion mechanisms. Today, researchers can design nanomotors with precise shapes, sizes, and functional components, greatly improving their efficiency and versatility.²

Advances in Multimodal Propulsion

Early nanomotors relied on single-mode propulsion systems, which limited their adaptability and efficiency. Multimodal propulsion systems are a solution and have led to improved performance in nanomotors, particularly in demanding conditions.

Three major multimodal systems have emerged in recent years: hybrid external field-powered propulsion, propulsion systems combining external fields with chemical fuels, and bio-hybrid propulsion.

Stimuli-responsive materials, including metals like Silver, Gold, and Platinum, have been central to these advances.

The unique electronic and catalytic applications of semiconductors like silicon, zinc oxide, titanium oxide, and molybdenum sulfide have also seen an increase in their use for developing multimodal propulsion systems for nanomotors in recent years. Furthermore, stimuli-responsive polymeric materials have been key for these systems, making them useful for prognostic therapeutic applications.³

Light-Driven Nanomotors with Unbelievable Speeds

Ever popular, self-propelled autonomous nanomotors have become even more desirable in recent years. Experts have been trying to develop nanomotors with ultra-fast speeds, allowing them to perform better for biomedical applications, particularly for targeted drug delivery.

In one study, experts have developed a gold-functionalized nanomotor with unmatched speeds using the photo-thermal properties of gold particles. The outer surface of a stomatocyte nanomotor was covered with a layer of 5 nm gold nanoparticles.

These gold stomatocytes were exposed to a 660 nm laser to investigate their autonomous motion experimentally. The results showed their direct autonomous motion in the opposite direction to the laser. This was especially revealing in comparison to the control groups, where no motion was seen. Only the Au-stomatocyte-based light-driven nanomotors demonstrated directional autonomous motion with exceptional velocities.

The experts manipulated the velocity by controlling the laser power, with just 1.5 W allowing the nanomotor to achieve an unbelievable velocity of 124.7 ± 6.6 μms^-1. The nanomotors' superior motility allows them to efficiently deliver targeted medicine across the cell membrane with an excellent biocompatibility and cell viability score of 90 %.⁴

Such light-propelled, biodegradable nanomotors are highly efficient, operate at ultra-fast velocities, and have a very high cell viability score.

Novel Shockwave-Driven Nanomotor for Treating Osteoporosis

Osteoporosis is a chronic disease marked by declining bone density. It can leave sufferers vulnerable to fractures, breakages, and other bone-related complications. In recent years, microneedle therapies have emerged as a promising treatment option as they offer minimally invasive but highly targeted transdermal drug delivery.

Among the mechanisms used to enhance microneedle penetration, the extracorporeal shockwave technique, which is based on high-energy pulses, has shown particular potential. It enables drugs to reach deeper into bone and tissue, while minimizing heat loss. This combination makes it a powerful tool for improving the effectiveness of treatments.

In a recent study, experts developed a novel extracorporeal shockwave-actuated nanomotor sealed into microneedles to protect patients from osteoporosis-based damage. They used highly biocompatible calcium phosphate nanoparticles in the nanomotor and zoledronic nanoparticles as the backbone of the microneedles, key for targeted drug delivery to the bones.

To test the penetration ability, the zoledronic nanomotor actuated by extracorporeal shockwaves was applied in in vivo studies for 30 minutes. Under extracorporeal shockwaves, the zoledronic nanoparticle microneedles reached a penetration depth of 1221.63 ± 98.80 µm, with an average depth of only 687.53 ± 181.27 µm.

The researchers also tested different concentrations of the nanomotors on bone marrow macrophages (BMM) and bone marrow mesenchymal stem cells (BMSC) for cytotoxicity. After 48 hours of interaction with BMMs and BMSCs, no cytotoxicity effects were observed, confirming their superior biocompatibility.

To confirm the local therapeutic effects, the effect of treatment of the nanomotor microneedle was tested on the left femur of an OVX rat model after six weeks of surgery. The scientists used a micro-CT reconstruction technique for the analysis, which revealed that the left femur treated with nanomotor-microneedle displayed a considerable increase in bone volume, compared to other traditional systemic intravenous administration treatments.

There was an improvement of about 15-20 % in bone volume per tissue volume and trabecular thickness. These findings hint at the microneedle's potential in preventing and treating osteoporotic fractures.⁵

Super-Assembled NMs for Removal of Lead from Human Blood

Lead poisoning remains a serious public health concern, with traditional treatments relying on hemoperfusion. Researchers have now developed nanomotor-based absorbents that offer a more efficient way to remove lead ions from the bloodstream.

Using a sequential super-assembly technique, scientists created nanomotors built from halloysite nanotubes embedded with gold nanoparticles. The surfaces were modified with polydopamine and DMSA to improve lead-binding properties. When activated by near-infrared light, the gold particles generated heat, propelling the nanomotors through self-thermophoresis and boosting their absorption capacity.

Tests in biological environments showed that these nanomotors removed lead ions 1.8x faster than passive materials, with an overall capacity of 151.769 mg/g. The process followed predictable adsorption kinetics, suggesting strong reliability.⁶

The successful testing of this highly efficient nanomotor-based absorbent reveals the potential of such autonomous heavy metal absorbents.

Challenges and Future Directions

Nanomotors have progressed significantly in the recent decade; however, certain challenges still need to be overcome. Research studies must focus on improving the monitoring techniques of nanomotors. This involves increasing the resolution and tracking accuracy by developing highly efficient techniques. Current imaging and tracking techniques need significant improvement to capture the full dynamics of nanomotor movement and surface interactions.

Controllability in complex environments is another issue. Generating sufficient force and torque for movement through dense biological fluids remains difficult. Researchers are exploring advanced co-polymers and novel fabrication techniques to overcome this limitation.

Furthermore, swarm-based nanomotor operation has recently become a focus of research. Coordinating multiple nanomotors to form the intended function efficiently and monitoring and regulating the effects of external factors is challenging. Experts are performing ground-breaking research in this domain, designing nanomotor-based swarms performing hierarchical functions.⁷

Nanomotors have come a long way in just two decades, evolving from experimental devices into practical technologies with real-world applications. As advances in materials, propulsion systems, and monitoring tools continue, their potential is only set to grow.

Further Reading

1. Liu, X. et. al. (2022). Intrinsic properties enabled metal organic framework micromotors for highly efficient self-propulsion and enhanced antibacterial therapy. ACS Nano. 16(9). 14666-14678. Available at: https://doi.org/10.1021/acsnano.2c05295
2. Wang, L. et. al. (2022). Artificial nanomotors: Fabrication, locomotion characterization, motion manipulation, and biomedical applications. Interdisciplinary Materials. 1(2). 256-280. Available at: https://doi.org/10.1002/idm2.12021
3. Wu, C. et. al. (2025). Micro/nanomotors from single modal to multimodal propulsion. Nano Research. Sci Open. 18(7). 94907105. Available at: https://doi.org/10.26599/NR.2025.94907105
4. Wang, J. et al. (2024). Ultrafast light-activated polymeric nanomotors. Nature Commu. 15. 4878. Available at: https://doi.org/10.1038/s41467-024-49217-w
5. Hu, F. et. al. (2024). A novel shockwave-driven nanomotor composite microneedle transdermal delivery system for the localized treatment of osteoporosis: a basic science study. International Journal of Surgery. 110(10). 6243-6256. Available at: https://www.doi.org/10.1097/JS9.0000000000001280
6. Cai, Y. et. al. (2025). Sequential super-assembled nanomotor adsorbents for NIR light-Powered blood lead removal. Separation and Purification Technology. 356. 129837. Available at: https://doi.org/10.1016/j.seppur.2024.129837
7. Chen, S. et. al. (2025). A roadmap for next-generation nanomotors. Nature Nanotechnology. 1-11. Available at: https://doi.org/10.1038/s41565-025-01962-9

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