A new weapon against resistant antibiotics – electromagnetic (light) activating molecules

A new type of motorized molecule that could kill specific bacteria shows hope

Scientists at Rice University led a team of researchers who developed light-activated hemithioisindigo (HTI) molecules that can destroy Gram-positive bacteria and the biofilms

These new molecules are different from and complementary to others created at Rice University, where others are also activated by light but burrow into cell membranes to kill them

Like Nobel laureate Bernard Feringa's drill, HTI-based molecules are activated by visible light rather than harmful ultraviolet radiation

Rice University alumnus Ana Santos is a postdoctoral global researcher at the Balearic Islands Health Institute in Parma, Spain, and Alexis van Venrooy is now a senior scientist at Genesis Therapeutics in Santiago and co-lead author

The HTI-based molecular machine consists of two parts: a thioisindigo cell connected

In this process, activated HTIs react with cellular and molecular oxygen, transmitting electrons to produce ROS, striking target cells

"They don't kill cells by mechanically tearing apart cell membranes

"An important advantage of these molecules is that their spectrum of activity is narrow and can selectively kill a specific group of bacteria, namely Gram-positive bacteria

Gram-positive bacteria lack an outer membrane (although they have a very thick layer of peptidoglycan), which seems to make them more susceptible to the ROS that oxidizes and destroys the cell wall

The researchers tested several variants of HTI on 7 Gram-positive strains and found that the molecule kills all bacteria

They also exposed Staphylococcus aureus colonies with or without reactive oxygen scavenger and found that Staphylococcus aureus with reactive oxygen scavenger weakened the effectiveness

The study showed that HTIs can also kill antibiotic-resistant long-lasting cells of different Gram-positive strains in as little as 25 minutes, faster

Santos said that because the treatment is BASED ON ROS rather than mechanical action, it does not harm mammalian cells

Hemithioindigo-Based Visible Light-Activated Molecular Machines Kill Bacteria by Oxidative Damage