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

Area of Science:

• Antimicrobial photochemotherapy
• Molecular machines
• Bacterial resistance

Background:

• Antibiotic resistance poses a significant global health challenge.
• Development of novel antimicrobial strategies is urgently needed.
• Existing therapies face limitations in efficacy and resistance development.

Purpose of the Study:

• To describe novel hemithioindigo (HTI)-based molecular machines with antimicrobial properties.
• To evaluate the efficacy of these machines against Gram-positive bacteria.
• To investigate the mechanism of action and potential for resistance development.

Main Methods:

• Visible light (455 nm) activation of HTI molecular machines.
• Testing against various Gram-positive bacterial strains, including MRSA.
• Assessment of efficacy against planktonic cells, persister cells, and biofilms.
• Mechanism of action studies involving reactive oxygen species (ROS) quantification.
• In vitro and in vivo synergy studies with conventional antibiotics.

Main Results:

• HTI machines demonstrated rapid killing of Gram-positive bacteria upon visible light activation.
• No detectable antibiotic resistance developed after repeated exposure.
• Effective elimination of S. aureus and B. subtilis biofilms within 1 hour.
• Antibacterial activity is mediated by oxidative damage via ROS.
• HTI synergized with antibiotics, reducing bacterial load and mortality in an MRSA infection model.

Conclusions:

• HTI-based molecular machines represent a promising new class of antimicrobial agents.
• Visible light activation provides a targeted and controllable therapeutic approach.
• The lack of resistance development and synergy with existing drugs highlight their potential clinical utility.