Chemically driven vehicles could deliver drugs against the stream

Hematite protruding from a polymer material to direct a vehicle along a chemical gradient--Courtesy of UCSD

Self-propelled drug delivery systems are an important advancement in early stages of research, giving hope that someday drugs can be transported via targeted, "smart" particles that have the ability to move where directed in the human body, even upstream of normal blood flow.

And scientists at the University of California have created particles that can travel along a gradient to possibly someday carry therapeutic molecules. Although not explicitly used in the realm of drug delivery yet, these small beads exhibit the mobility that preclinical vehicles have demonstrated in the past, such as nano-sized robots, cilia-equipped carriers and rocket-powered delivery platforms.

The new vehicles may be called living systems, in that they resemble living beings by responding to their environment. The scientists started with a small cube of hematite and wrapped a polymer around it. The hematite protrudes in one direction outside the polymer, and the hematite reacts to chemical gradients because it conducts electricity, moving the whole vehicle forward along that gradient.

"Living systems change their behavior according to their environment," UCSD researcher Jérémie Palacci said in a statement. "So the question was, can we design a particle that can sense its environment with no neural system or biological parts. This is a basic feature of living systems, and the idea was to implement that in a synthetic one."

The scientists published their work in the journal Science Advances.

The system mimics particles and organisms in nature, such as plankton moving toward sunlight. But the researchers are still in the very early stages and admit the drug application will be a ways away.

"If you can design particles that can feel their environment and you went one step further into 'smart' particles that could direct themselves towards specific organs, you could think of particles that swim against the blood stream to fix clogged arteries," Palacci said.

- here's the UCSD report