Microscopic magnets could revolutionize drug delivery

Targeting medications inside the body is one of the great challenges of modern medicine. Most drugs are simply allowed to diffuse throughout the body, eventually coming into contact with the organ or tissue it was intended to affect, but a team of Chinese scientists may have found a better way. As with many of life’s problems, this one could be solved with magnets.

Kezheng Chen and Ji Ma from Quingdou University of Science and Technology have published a study demonstrating a new type of magnetic crystal that can be guided throughout the human body by doctors. These materials, known as superparamagnetic crystals, have existed for years. The main difference here is that researchers have managed to increase the size of each crystal by several thousand times. Even so, they’re still absolutely minuscule compared with your own cells; just a few hundred micrometers across. Making the crystals larger takes them from an interesting experimental curiosity to a potentially useful material.

In theory, superparamagnetic particles can be ideal for drug delivery because an external magnetic field could essentially drag them around the body. The problem with smaller superparamagnetic crystals is that they were too hard to control, and they would almost immediately clump together when a magnetic field was removed. A larger crystal is more responsive to field intensity and gradients, and it should stay about where you put it. However, past efforts to produce them failed.

Smaller superparamagnetic crystals clumping together.

Precisely controlled high temperature and pressure are needed to create superparamagnetic crystals, which have the interesting property of flipping polarity based on temperature. The high degree of stress on the forming crystals causes the structure to buckle and produce a pockmarked surface as micro-particles of magnetite are ejected. This is what gives them their superparamagnetic properties. Similar magnetite crystals that are formed in lower temperatures and pressures have much weaker magnetic properties.

The development of larger superparamagnetic crystals could allow doctors to create special crystals for drug delivery. That could revolutionize cancer treatment in particular. Chemotherapy and radiation treatments cause damage to tissues throughout the body, but the higher metabolism of tumors causes them to be affected more severely. If you could steer a chemotherapy drug directly to the tumor via an external magnetic field, you could vastly reduce the side effects. Engineers might also be able to use these larger superparamagnetic crystals as a sort of “smart fluid.” A vehicle’s suspension or a prosthetic limb could alter their rigidity on command with the application of a magnetic field.