What are the ways to target medicines to specific areas in the body where they are needed?
Scientists have been studying this for a long time. One example is sending cancer drugs straight to a tumor so they work only there and don’t cause side effects in the rest of the body.
Researchers are working to find carrier particles that can hold active ingredients. These particles need to meet several critical criteria:
- They should be able to carry as many drug molecules as possible.
- They should be easy to guide through the bloodstream using a simple method, like ultrasound.
- Traceable inside the body using noninvasive imaging so researchers can confirm whether the medicine reaches the right place.
Finding one particle that meets all these needs has been difficult, but research led by ETH Zurich has now discovered a special class of particle that fulfills all of these requirements.
Besides their effectiveness, these particles look appealing under a microscope—resembling tiny paper flowers or desert roses. Very thin petals form flower-like shapes from them. The flower particles range from one to five micrometers in diameter, just a bit smaller than a red blood cell.
Because of their shapes, the particles offer two advantages:
The flower particles have a large surface area compared to their size, with tiny pores between the petals that can absorb a lot of medicine. They also scatter sound waves or can have light-absorbing molecules coated on them, which makes them easy to see with ultrasound or light-based imaging.
Paul Wrede, co-author of the study and doctoral student in Razansky’s group, said, “Previously, researchers primarily investigated tiny gas bubbles as a method of transport through the bloodstream using ultrasound or other acoustic methods.”
“We have now demonstrated that solid microparticles can also be acoustically guided.”
This special class of particles has the advantage over bubbles in that they can be loaded with larger quantities of active ingredient molecules.
The researchers showed that the flower particles could hold a cancer drug in lab experiments. They then injected the particles into mice’s bloodstreams and used focused ultrasound to keep the particles in a specific spot inside the body. This worked even with the fast-moving blood around the particles. Focused ultrasound uses concentrated sound waves to target a small area.
Wrede said, “We don’t just inject the particles and hope for the best. We control them.”
The researchers hope this technology will one day be used to deliver medicines to tumors or clots that block blood vessels.
The particles can be made from different materials and have various coatings depending on their use. The researchers chose an imaging method to control their position.
The key to how particles work is their shape, not the material they are made from. In their study, the researchers looked closely at flower-shaped particles made of zinc oxide. They also tested particles made of polyimide and a mix of nickel with organic materials.
The team is looking forward to refining their concept with animal testing first.
Journal Reference:
- Kim DW, Wrede P, Estrada H, Yildiz E, Lazovic J, Bhargava A, Razansky D, Sitti M: Hierarchical Nanostructures as Acoustically Manipulatable Multifunctional Agents in Dynamic Fluid Flow. Advanced Materials. DOI: 10.1002/adma.202404514