Micro-swimmers that remove disease-causing bacteria from water

IBEC researchers, together with their collaborators from the Max Planck for Intelligent Systems in Stuttgart, have engineered tiny robots that can remove disease-causing bacteria, such as E. coli, from water.

Contaminated drinking water is a persistent public health problem that can cause potentially life-threatening illnesses when proper treatment isn’t available, as in many areas of the world. It can be disinfected with chlorine or other disinfectants, but some hardy bacteria and other microorganisms stick around and can be hard to remove. Sometimes, the byproducts of these disinfectants can be harmful to human health as well.

The study published in ACS Applied Materials & Interfaces, which was led by postdoc Diana Vilela, describes the Smart Nano-Bio-Devices group’s development of tiny robots that can swim around water and clean up disease-causing bacteria. In these “two-faced” spherical particles, one face is made with magnesium, which reacts with water to produce hydrogen bubbles to propel the microbots. The other face is made of alternating iron and gold layers topped by silver nanoparticles. Bacteria stick to the gold and are killed by the silver nanoparticles.

“Our lab tests showed that the microbots can zoom around in water for about 15 to 20 minutes before running out of magnesium, and they trapped more than 80 percent of E. coli in water spiked with a high concentration of the bacteria,” explains Samuel Sanchez, ICREA professor and head of IBEC’s Smart Nano-Bio-Devices group. “Afterwards, because of the iron’s magnetic properties, the microbots can beremoved easily with a magnet, without leaving behind any harmful waste in the water.”

The tiny robots can be seen in action in a video made by ACS.

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Diana Vilela, Morgan M. Stanton, Jemish Parmar & Samuel Sanchez (2017). “Microbots decorated with silver nanoparticles kill bacteria in aqueous media”. ACS Applied Materials & Interfaces, 10.1021/acsami.7b03006

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The authors acknowledge funding from the Alexander von Humboldt Foundation in Germany, the European Research Council and the Max Planck Institute.