Magnetically Controlled Robots Offer Precision in Targeted Drug Delivery

A group of scientists from Nanyang Technological University have developed grain-sized soft robots that can be guided by magnetic fields for targeted drug delivery. Published in Advanced Materials, the study presents the first documented example of tiny robots capable of carrying up to four distinct medications and releasing them in controlled doses and sequences.

The research team reports that these newly developed miniature robots provide precise functionality, potentially improving therapeutic outcomes while minimizing side effects. Unlike previous small-scale robots, which could carry up to three types of drugs and lacked programmable release, these robots offer greater control and versatility.

The NTU team had previously developed small robots maneuverable by magnets, capable of complex movements such as "swimming" through narrow spaces and grasping tiny objects.

Lead Investigator and Assistant Professor Lum Guo Zhan from the School of Mechanical and Aerospace Engineering (MAE) noted that the team drew inspiration from the 1960s film Fantastic Voyage, where a submarine crew is miniaturized to repair damage in a scientist's brain.

What was a scenario in a sci-fi movie is now becoming closer to reality with our lab’s innovation. Traditional methods of drug delivery, like oral administration and injections, will seem comparatively inefficient when stacked up against sending a tiny robot through the body to deliver the drug exactly where it is needed.

Lum Guo Zhan, Lead Investigator and Assistant Professor, School of Mechanical and Aerospace Engineering, Nanyang Technological University

Highly Dexterous and Reprogrammable Drug-Dispensing Capabilities

The grain-sized robot was created using smart magnetic composite materials, combining non-toxic magnetic microparticles and polymers.

This newly developed soft robot is highly agile, capable of rapidly rolling and crawling to avoid obstacles. This feature sets it apart from current tiny robots, which lack precise orientation control. This agility gives it strong potential for navigating the complex, unstructured environment within the human body.

In lab experiments simulating human body conditions, the robot demonstrated its ability to carry multiple drugs and deliver them in a controlled manner. Placed on a surface divided into four sections, it moved between sections at speeds ranging from 0.30 mm to 16.5 mm per second, releasing a different drug in each designated area.

In another experiment, researchers used a thicker liquid to assess the robot’s ability to deliver pharmaceuticals under more challenging conditions. The results showed that the robot could navigate this environment and release adequate amounts of drugs over eight hours.

Additionally, the robot demonstrated minimal drug leakage, even after continuous movement over the eight-hour period. Its ability to precisely control drug release with minimal leakage makes it a promising tool for treatments requiring the timed delivery of multiple medications to specific locations.

Research Fellow Yang Zilin and Ph.D. Graduate Xu Changyu from the School of MAE were also among the study's authors.

“These findings show that our soft robot could potentially play a key role in the future of targeted drug delivery, especially in those treatments such as cancer therapies that need precise control over multiple drugs,” said Yang Zilin, a Research Fellow.

As a doctor who performs minimally invasive procedures, we currently use a catheter and a wire to move through blood vessels to treat problems. But I can foresee it will not be long before this is superseded by tiny robots that can autonomously swim through the body to reach places we cannot get to with our tools. These robots could stay in place and release medication over time, which would be much safer than leaving a catheter or stent inside the body for a long time. This is a medical breakthrough on the verge of happening.

Dr. Yeo Leong Litt Leonard, Senior Consultant and Surgeon, Department of Medicine, National University Hospital

The NTU research team is now focused on further miniaturizing their robots to facilitate advanced treatments for conditions such as brain tumors, bladder cancer, and colorectal cancer. Before these robots are applied in medical settings, the team plans to carry out additional performance tests using organ-on-chip devices and animal models.

Video Credit: Nanyang Technological University 

Journal Reference:

Yang, Z., et al. (2024) Magnetic Miniature Soft Robot with Reprogrammable Drug‐Dispensing Functionalities: Toward Advanced Targeted Combination Therapy. Advanced Materials. doi.org/10.1002/adma.202408750.