Scientists discover tiny rocket engines inside malaria parasites

Malaria parasites run microscopic rocket engines. Scientists at the University of Utah have figured out how — and the answer may reopen a frontier in drug development that researchers didn't know was there.

The discovery, published in PNAS, centers on Plasmodium falciparum, the parasite causing the deadliest form of malaria. Inside every parasite cell are iron crystals — hemozoin — that spin continuously, powered by the breakdown of hydrogen peroxide. The same chemical reaction propels rockets. No one had observed it in a biological system before.

The crystals are a waste product. When the parasite digests hemoglobin inside red blood cells, it produces heme as a byproduct, which is toxic in its free form. The parasite crystallizes the heme into hemozoin to neutralize it. What nobody understood was why those crystals moved.

"People don't talk about what they don't understand, and because the motion of these crystals is so mysterious and bizarre, it's been a blind spot for parasitology for decades," said Paul Sigala, associate professor of biochemistry at the University of Utah.

Erica Hastings, a postdoctoral fellow and co-author, designed experiments to find out. She confirmed that hydrogen peroxide alone could cause isolated crystals to spin, even outside the parasite. When parasites were grown under low-oxygen conditions — which reduces hydrogen peroxide production — the crystals slowed to about half their usual speed while the parasites remained otherwise healthy.

The mechanism is straightforward: hydrogen peroxide breaks down into water and oxygen, releasing energy that propels the crystal. "This hydrogen peroxide decomposition has been used to power large-scale rockets," Hastings said. "But I don't think it has ever been observed in biological systems."

The motion appears to serve a purpose. Keeping the crystals in constant motion prevents them from clumping together, which would reduce their surface area and limit how efficiently they can sequester toxic heme. The spinning may also help the parasite manage hydrogen peroxide stress more generally — breaking down excess peroxide before it damages the cell.

The implications for malaria drug development are direct. The mechanism is specific to the parasite — humans don't have these crystals — which means interfering with the hydrogen peroxide propulsion system could be a targeted approach with fewer side effects. "If we target a drug to an area that's very different from human cells, then it's probably not going to have extreme side effects," Hastings said.

Sigala was direct: if you can block the chemistry at the crystal surface, that alone might be sufficient to kill parasites.

The discovery also matters beyond parasitology. The researchers note that these spinning crystals represent the first known example of a self-propelled metallic nanoparticle in biology — a category that materials scientists have been engineering synthetically for applications in drug delivery and microrobotics. Understanding how biology solves the same problem may inform those fields.

Malaria killed roughly 600,000 people in 2023, most of them children under five in sub-Saharan Africa. Drug resistance is a persistent challenge — the parasite evolves defenses against every new treatment brought to bear against it. Whether this discovery leads to a new drug class depends on years of follow-on research. But it adds a target researchers didn't know existed, in a disease that needs every new angle it can get.