By mimicking the flexibility of real blood cells, imitation cells made from a polymer can be used for drug release to places that normal mechanisms just can’t get to. The delivery method could also be used for contrast agents for medical imaging or to replace a blood transfusion.
These devices can squeeze through spaces smaller than their own diameter, just as real cells do. A concaved tire shape is what enables blood cells’ flexibility. In the body, blood cells start out as spherical cells, which then collapse into mature red blood cells following exposure to various substances.
To create synthetic particles that have the same ability, researchers at the University of California, Santa Barbara, add small balls of a PLGA polymer to a solvent, causing the spheres, which measure about 7 μm across, to collapse into a biconcave shape. The researchers coat the particles in a layer of protein. Then the polymer core is dissolved, leaving a pliable biodegradable protein shell that has mechanical properties similar to red blood cells.
The implications of the technology could be far reaching. For example, researchers are exploring how to use these shapes for drug delivery to targeted areas at a more constant concentration. The team exposed the shapes to heparin to show that they can carry drugs. Heparin was absorbed and the protein shells released the drug when they were moved to an area of lower concentration. Substances such as iron oxide nanoparticles that increase contrast in magnetic resonance imaging could also be delivered. The researchers have also experimented with sickle-cell blood shapes to see whether they can learn more about how the misshapen blood cells travel through the body.
Even more astounding, the particles could be used for blood transfusions. Researchers conducted in vitro experiments and found that hemoglobin-coated particles picked up oxygen in an oxygen-rich environment and released it later when the concentration was lower. If the particles do the same thing in vivo, they could be used in place of traditional transfusion.