Microswimmers use ‘good’ bacteria to target harmful biofilms

A paper by IBEC’s Smart nano-bio-devices group addresses the problem of biofilms, the “microbe cities” that enhance cell-to-cell communication for bacteria, allowing infection to thrive and increasing the chances of evading the immune system. In the body, they can be found in a wide variety of microbial infections, such as in the lungs of cystic fibrosis or chronic obstructive pulmonary disease patients.

Biofilm colonies are usually resistant to antibiotics and require targeted methods of removal. One method uses nanoparticles as carriers for antibiotic delivery, where they randomly circulate in fluid until they make contact with the infected areas. These are not very effective, however, as they need to be able to get much closer to the biofilm.

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Above left: MSR-1 cells captured within a microtube; above right: biohybrid trapped in an E. coli biofilm

In the paper published in ACS Nano, the group and their collaborators at Stuttgart’s Max Planck Institute for Intelligent Systems demonstrate that the non-pathogenic bacteria Magnetosopirrillum gryphiswalense (MSR-1) can be integrated with drug-loaded microtubes to build controllable biohybrid systems or ‘microswimmers’ capable of antibiotic delivery to target an infectious biofilm.

“Applying external magnetic guidance capability and swimming power to the MSR-1 cells, our biohybrids can be directed to and forcefully pushed into mature E. coli biofilms,” explains ICREA Research Professor and IBEC group leader Samuel Sánchez. “The release of the antibiotic, ciprofloxacin, is triggered by the acidic microenvironment of the biofilm.”

Checking the biofilms they targeted with their biohybrids after 24 hours and then 48 hours, the researchers saw that the biofilms weren’t coming back. “Our biohybrids penetrate deep into the layers and impede the biofilm’s progression,” surmises Samuel.

The capability of non-pathogenic bacteria to target and dismantle harmful biofilms demonstrated here indicates a promising use for biohybrid systems in anti-biofilm applications.

Source article: Morgan M. Stanton, Byung-Wook Park, Diana Vilela, Klaas Bente, Damien Faivre, Metin Sitti, and Samuel Sánchez (2017). Magnetotactic Bacteria Powered Biohybrids Target E. coli Biofilms. ACS Nano, 10.1021/acsnano.7b04128

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