Nanoengineers at the University of California, San Diego, have developed anti-pneumonia microbots that swim around the lungs, deliver drugs and are used to clear life-threatening bacterial pneumonia infections. In mouse tests, the microbots safely eliminated the pneumonia-causing bacteria with a 100 percent survival rate, compared to untreated mice that all died within three days of infection. The results of the study were published in Nature Materials on the 22nd.
The microbots are made of algae cells dotted with antibiotic-filled nanoparticles. The algae provide the motility that allows the microbots to swim around and deliver antibiotics directly to more bacteria in the lungs. The antibiotic-laden nanoparticles are made of tiny biodegradable polymer spheres that are covered with the cell membranes of neutrophils, a type of white blood cell. What makes these cell membranes special is that they absorb and neutralize inflammatory molecules produced by bacteria and the body’s immune system. This allows the microbots to reduce harmful inflammation, which makes them more effective in fighting lung infections.
The team used the microbots to treat mice suffering from an acute and potentially fatal pneumonia caused by Pseudomonas aeruginosa. This type of pneumonia typically affects patients who are intubated in intensive care units. The researchers applied the microbots to the mice’s lungs through a tube inserted into the trachea. The infection cleared completely after a week, and all mice treated with the microbot survived for 30 days, while the untreated mice died within three days.
Treatment with the microbot was more effective than intravenous antibiotics. The latter required a dose of antibiotics 3,000 times higher than the microbot to achieve the same effect. In comparison, the microbot delivered 500 nanograms of antibiotics per mouse at a time, while the intravenous injection provided 1.644 milligrams of antibiotics.
The team’s approach was very effective because it transported the drug to where it was needed, rather than spreading it to other parts of the body. The results suggest that targeted drug delivery combined with active movement of microalgae can improve therapeutic efficacy in a safe, simple, biocompatible and long-lasting manner.
[Editor-in-Chief’s Circle
By intravenous injection, sometimes only a small fraction of the antibiotic will enter the lungs. This is why many of the current antibiotic treatments for pneumonia are ineffective, leading to high mortality rates in patients with severe disease. In this new study, data from mouse tests show that the microbot improves the penetration of antibiotics and kills bacterial pathogens, thus saving the lives of more patients. Also important is the demonstration that it is safe to put algae cells into the lungs and that our body’s immune cells can effectively digest the algae and any remaining nanoparticles – in other words, “zero residue” of toxic substances.
