Swimming algae microrobots deliver antibiotic nanoparticles to lungs

The researchers refer to the algae cells as ‘microrobots’, as the organisms were harnessed to deliver antibiotic-filled nanoparticles throughout the lungs of mice.

The antibiotics were attached to the surface of algae cells, which then delivered the treatment through the movement of ‘swimming’ around the lungs.

Use of the microrobots proved to be effective in treating the pneumonia experienced by the mice, with those receiving the antibiotic-laced algae recovering and resulting in 100% survival rate. For those mice that received no treatment, all had died within three days of infection.

The pneumonia that the mice were treated for is caused by the bacteria pseudomonas aeruginosa​. This form of pneumonia can affect patients who receive mechanical ventilation in intensive care units.

The antibiotics are delivered via nanoparticles, which are comprised of tiny biodegradable polymer spheres that are coated with the membranes of neutrophils – a type of white blood cell.

In addition to delivering the antibiotics, the cell membranes also absorb and neutralize inflammatory molecules produced by bacteria and the body’s immune system. The researchers stated that the microrobots are therefore able to reduce inflammation and, as such, be more effective in fighting lung infections.

The hope is that the research may prove to help develop a form of antibiotic treatment that is more effective than current means of drug delivery, through intravenous (IV) injection.

“With an IV injection, sometimes only a very small fraction of antibiotics will get into the lungs. That’s why many current antibiotic treatments for pneumonia don’t work as well as needed, leading to very high mortality rates in the sickest patients,”​ said Victor Nizet, professor at UC San Diego School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences.

By comparison, the dosing levels required by IV injection are 3,000 times higher than that used in this piece of research, with a dose of microrobotics containing 500 nanograms of antibiotics against 1,644 milligrams in IV delivery.

The dose of microrobots was delivered via a tube inserted into the windpipe, entering directly into the lungs. After treatment, the body’s immune cells can digest the algae and any remaining nanoparticles, leaving nothing in the lungs that would be considered toxic, the researchers stated.

For the research team, the work continues on a pathway that has also seen them develop treatments that are delivered into the stomach and directly into the blood. All of these projects hinge on the use of nanotechnology and microrobots to deliver the treatments.

On the most recent work, the researchers plan to conduct further studies to understand how the microrobots interact with the immune system, before validating the treatment and scaling up into larger animals – ultimately, potentially ending up in human studies.