The four spikes on a new nanocrystal developed in Spain spin up under light and move through liquid, blasting any bacteria unfortunate to be in their path. The development could spell trouble for bacteria that resists traditional drug treatments.
Antimicrobial-resistant bacteria are becoming a real problem. According to the CDC, the superbugs were responsible for nearly 5 million deaths worldwide in 2019 with more than 2.8 million people in the US coming down with some kind of treatment-resistant infection every year. As germs continue to evolve to evade our ways of killing them, scientists are racing to expand the arsenal we can use against them.
We've already seen tunable antibacterial polymers that should be more effective against superbugs; the use of a virus to target bacteria that go dormant to avoid detection; and a coating that turned hospital curtains into bacteria-blasting surfaces. Now, researchers at the Institute of Chemical Research of Catalonia (ICIQ) in Tarragona, Spain, have enlisted silver micromotors into the fight.
Fundamentally, the motors they produced are crystals made from silver phosphate. Silver has long been understood to have antibacterial properties with silver salts used to heal wounds over 3,000 years ago in Ancient Greece. When these crystals, which measure just five micrometers wide, are put into water and exposed to light, they begin to dissolve, releasing oxygen, silver ions and free radicals. The release of these compounds not only causes the crystals to drive around the liquid, but the silver ions they release weaken the walls of bacteria in the water causing them to whither and die.
While silver has been studied before as a way to fight infection, the researchers say that because their method adds in propulsion, the ions are more widely dispersed, making them even more effective in degrading nearby bacteria which, in this study, included Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria – two strains that are developing resistance to traditional treatments. To prove that point, when the researchers took away the propulsive factor from the tiny motors, they found that their effectiveness went down significantly.
“This work is important because we report a synergistic effect that includes the self-propulsion capability of the micromotors under light stimuli, allowing greater diffusion and dispersion of silver ions as well as released free radicals,” said lead researcher Dr. Katherine Villa at ICIQ.
The team, which has previously used micromotors covered in laccase to turn urea into ammonia – a potential source of fuel, says that after its silver crystals drive around and dissolve, the silver particles can be recovered through a filtration process and used again.
The study has been reported in the journal Advanced Optical Materials.
Source: ICIQ
