It may sound like something from a science fiction movie: tiny medical nanobots propelling through the body taking tissue samples, performing surgical repairs or delivering drugs. For the first time, however, researchers at the University of California, San Diego tested such devices on animals and successfully administered zinc-based, acid-powered, self-destructing micromotors inside living mice.

Chemical and Engineering News reports the researchers' goal was to test the micromotors for drug delivery. Gold nanoparticles were embedded in the micromotors' polymer coat, and the tiny machine was given to the mice orally. It propelled itself inside the mouse's body until reaching the stomach, where it swam to the stomach lining and delivered the gold nanoparticle dose.

The self-propulsion of the micromotors greatly improves the tissue penetration and drug retention, according to researchers.

The mice did not have an immune system reaction to the micromotors; there was no toxicity. The micromotors simply dissolved in the mice stomachs without generating toxic by-products.

According to BBC, this technology can be useful for treating ailments like peptic ulcers and other stomach disorders.

How Micromotors Work

The super-tiny micromotors used in the mice experiment measured 20 micrometers long, about the width of a human hair. These tiny machines are rugged enough to survive the gastrointestinal tract autonomously. When their task is completed, they self-destruct without leaving harmful chemicals.

Recently, researchers have designed micro-sized motors that react with surrounding chemicals to produce jets of bubbles, which propel them forward. These micromotors can swim and perform medical tasks, like sorting cells in tubes of blood.

Joseph Wang, a nanoengineer at the University of California, explains in the study his early designs used hydrogen peroxide as the chemical solution the micromotors reacted with to propel, but the effects were toxic. Wang and his colleagues want to design new motors that can use chemicals naturally found inside a body, such as gastric juices, as the fuel so there are no toxic by-products.

Jet-propelled micromotors could one day be given orally to human patients in the medical field. The micro-machines would penetrate the thick layer of mucus in a patient's stomach to deliver drugs and remain embedded until dissolved.

While the medical use of this technology on people has a long way to go, the successful administration to animals is a critical first step.