The latest reversal of Rice University nanoscale drills has been activated by visible light instead of ultraviolet (UV) as in previous versions. It has also been shown (Bacterial training exercises are upgraded) to be effective in killing bacteria by testing for real infections. Chemist Rice James Tour and his team successfully tested six variants of molecular machines. All penetrated the membranes of gram-negative and gram-positive bacteria within two minutes. For bacteria without a natural defense against mechanical intruders, resistance is useless. This means that they cannot develop resistance, which can provide a strategy for killing bacteria that have become immune to conventional antibacterial therapy over time.
“I tell students that antibiotic-resistant bacteria will make COVID a walk in the park if they’re my age,” Tour said. “Antibiotics won’t be able to keep 10 million people a year from dying of bacterial infections. But this really stops them.”
The breakthrough study was led by Tour and Rice alumni Ana Santos and appears in Science Advances.
Because extended exposure to UV can be damaging to humans, the Rice lab has been refining its molecules for years. The new version gets its energy from still-blueish light at 405 nanometers, spinning the molecules’ rotors at 2 to 3 million times per second.
It’s been suggested by other researchers that light at that wavelength has mild antibacterial properties of its own, but the addition of molecular machines supercharges it, said Tour, who suggested bacterial infections like those suffered by burn victims and people with gangrene will be early targets. The engines are based on the Nobel Prize-winning work of Bernard Feringa, who in 1999 developed the first molecule with a rotor and reliably rotated the rotor in one direction. Tour and his team presented their advanced exercises in the 2017 documentary Nature.
The first tests of the new molecules in a rice laboratory (Bacterial training exercises are upgraded) on burn infection models confirmed their ability to kill bacteria quickly, including methicillin-resistant Staphylococcus aureus, a common cause of infection, skin and soft tissue responsible for more than 100,000 deaths in 2019.
The team achieved the activation of visible light by adding a nitrogen group. “The molecules are further modified with various amines either in the stator (stationary) or in the rotor part of the molecule to promote the connection between the protonated amines in the machines and the negatively charged bacterial membrane,” said—Liu, who is now a scientist at Arcus Biosciences in California. The researchers also found that the machines effectively degraded biofilms and persistent cells that became inactive to prevent antibacterial drugs.
“While an antibiotic can kill most of the colony, there will always be some persistent cells that don’t die for some reason,” Tour said. “But training doesn’t matter.”
As with previous versions, the new machines also promise to revive antibacterial drugs that are not considered effective. “Drilling into the membranes of microorganisms can introduce ineffective drugs into cells and overcome the insect’s own or acquired antibiotic resistance,” said Santos, who is a third-year postdoctoral student. the global community that brought him to Rice two years ago and continues. at the Health Research Institute in the Balearic Islands in Palma, Spain.
The laboratory is working to better target bacteria to minimize damage to mammalian cells by combining bacterial-specific peptide tags with holes to target pathogens of interest. “But even without that, the peptide can be used in an area with a high concentration of bacteria, such as a burn wound area,” Santos said.
