BY ANTHONY KING
Tiny algae-based robots deliver drugs throughout lungs in mice.
A microrobot has been designed to rove around lungs and disperse life-saving drugs. The tiny robots were made by bolting together green microalgae (Chlamydomonas reinhardtii) and PLGA polymer nanoparticles coated with red blood cell membranes, which were loaded with an anti-cancer drug.
When inserted into the lungs of mice, the bots moved around and efficiently dispersed the chemo drug, doxorubicin (Science Advances, DOI:10.1126/sciadv.adn615). The improved dispersal and longer retention of the drug boosted the average survival of lab mice with lung cancer from 32 to 55 days.
‘The algae-based robot had better lifespan than our previous robots with synthetic motors, such as magnesium bubble propulsion, which typically lasted 20 minutes,’ says study scientist Zhengxing Li at the University of California, San Diego. ‘The algae were still motile for up to 48 hours in simulated lung fluid at body temperature.’
The membrane of blood cells was cloaked around the algae to camouflage them from the host immune response. The movement of the microalgae appeared also to help them evade macrophages – immune cells in the lungs that swallow foreign particles and microbes. This allowed the algae to better distribute the chemo drug in the mouse lung, as well as prolong their retention.
‘The algae are made for swimming in water, and so it is interesting that they seem to do so well in the mucus of the lung, even for longer periods,’ comments Peer Fischer, nanoscientist at the University of Heidelberg, Germany.
Previously, the San Diego group had reported on microrobots delivering antibiotics to the lungs of mice to treat bacterial pneumonia (Nature Materials, DOI: 10.1038/s41563-022-01360-9).
Unlike some microbes, microalgae do not provoke a strong response from the immune system, according to Li. Also, the green microalgae do not show any proliferation at body temperature, which enhances their biosafety score, he adds. The San Diego group is now working on delivering a treatment for cystic fibrosis to control inflammation in the lungs. They also are working on a less invasive way to get the microrobots into lungs rather than via a plastic tube.
This research has created an innovative biohybrid approach to create a ‘smart, active drug delivery system’, says Christopher Bettinger, a biomedical engineer at Carnegie Mellon University in Pittsburgh, Pennsylvania. ‘It’s a unique and innovative combination of living components integrated with drug delivery systems that has the potential to revolutionise how bioactive compounds are imagined,’ he adds.
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