In the near future, micro-robots may be delivering drugs in our bodies, but there are still hurdles to be removed before this vision can be realized. Now, researchers have developed a “bottle opener” micro-robot that can drill into cancer cells and keep the drug from being washed away by blood or other fluids while dropping the drug payload.
If the drug is delivered directly to the target tissue, the drug works best. Unfortunately, the body is a dynamic environment where the drug can be dispersed, reducing the drug’s ability to play in the target area and causing unnecessary side effects in healthy tissue. It is well known that chemotherapy drugs wreak havoc in the body.
In recent years, scientists have been experimenting with micro-robots to get drugs exactly where they are needed. To do this, micro-robots need to stay in that place for a certain amount of time. But this is a challenge in itself, because body fluids tend to push them around. This is the problem that researchers at the University of Daegu, South Korea, have solved.
Previous micro-robots have fixed them in place through a magnetic field applied by a doctor from outside the body. But in the new study, the team designed a robot that doesn’t need to maintain a magnetic field for long. The new miniature robot is shaped like a bottle opener with a needle at the top. The exterior is coated with a coating of nickel and titanium oxide, allowing it to be guided by magnetic forces. The drug can then be loaded into the needle and entered into the pores of the “bottle opener” stent.
The principle is that doctors use a magnetic field to guide the robot to the human body’s desired position, and once it gets there, it will pierce the target cell. This way, it can stay there until the task is complete. The researchers tested micro-robots in liquid-filled cavities, guiding them to attach to tissue samples. It takes 55 seconds to manually manipulate the magnetic field, but a specially designed automatic aiming system takes only 7 seconds to complete.
The team then found that the needle needed to be removed at a flow rate of 480 mm per second. This works well in some places—- for example, the flow rate of the blood vessels in the small arteries is about 100 mm per second – but larger veins and arteries can exert more pressure. In another experiment, the team tested the design on human colorectal cancer cells. Sure enough, micro-robots can effectively target and kill cells.
While it still has a long way to go in human applications, the team says the next step is to find ways to put more drugs on micro-robots and develop better magnetic fields to guide them.
The study was published in the journal Journal of Advanced Advanced Materials.