Researchers at the Institute of Bioengineering of Catalunya (IBEC), along with collaborators from the Max Planck for Intelligent Systems in Stuttgart, have designed tiny robots that can eliminate disease-causing bacteria, such as Escherichia coli, from water.
Water contamination is one of the most persistent problems of public health around the world today. Resistance of some pathogens to conventional disinfectants can require the combination of multiple disinfectants or increased disinfectant doses, which may produce harmful byproducts.
The lack of clean water in many areas around the world is a persistent, major public health problem. One day, tiny robots could help address this issue by zooming around contaminated water and cleaning up disease-causing bacteria. Scientists report a new development toward this goal in the journal ACS Applied Materials & Interfaces.
Drinking water contaminated with pathogenic bacteria’s can cause serious illnesses that, in areas with poor medical services, are potentially life-threatening without proper treatment.
A micro-robot is a very small robot built to do specific tasks. In general, a microrobot is just a bit larger than a nano-robot, which is created on the nanoscale. Microrobots are usually visible, whereas some nanobots are not immediately visible to the human eye.
Here, we describe an efficient method for disinfecting Escherichia coli (E. coli) and removing the bacteria from contaminated water using water self-propelled microbots decorated with silver nanoparticles (AgNPs).
The structure of a spherical microbot consists of a magnesium (Mg) microparticle as a template that also functions as a propulsion source by producing hydrogen bubbles when in contact with water, an inner iron (Fe) magnetic layer for their remote guidance and collection, and an outer AgNP-coated gold (Au) layer for bacterial adhesion and improving bactericidal properties.
The active motion of microbots increases the chances of the contact of silver nanoparticles on the microbot surface with bacteria, this provokes the selective Ag+ release in their cytoplasm, and the microbot self-propulsion increases the diffusion of the released Ag+ ions.
In addition, the silver nanoparticles coated gold cap of the microbots has a dual capability of capturing bacteria and then killing them.
Then, we have demonstrated that silver nanoparticles coated microbots are capable of efficiently killing more than 80% of E. coli compared with colloidal silver nanoparticles that killed only less than 35% of E. coli in contaminated water solutions in 15 min.
After the capture and extermination of bacteria, magnetic properties of the cap allow collection of microbots from water along with the captured dead bacteria, leaving water with no biological contaminants. The presented biocompatible microbots offer an encouraging method for rapid disinfection of water.
According to Samuel Sanchez, one of the owners of this project, lab testing showed that the particles can motor around in water for 15 to 20 minutes before the magnesium is spent. They trapped more than 80% of E. coli in water spiked with a high concentration of the bacteria.
After the bacteria is captured the microbots can be removed easily with a magnet due to the magnetic properties, without leaving behind any harmful waste in the water.