Rationally designed photosensitizers with enhanced spin-orbit coupling for high quantum yield and potent...

Area of Science:

• Photochemistry
• Materials Science
• Microbiology

Background:

• Photodynamic therapy (PDT) shows promise for antibacterial treatment.
• Traditional photosensitizers often have low reactive oxygen species (ROS) quantum yields, limiting their efficacy.
• Enhancing ROS production is crucial for effective bacterial killing via PDT.

Purpose of the Study:

• To design and synthesize novel photosensitizers with improved ROS quantum yield for antibacterial PDT.
• To enhance photosensitizer performance by increasing spin-orbit coupling (SOC) and introducing membrane-anchoring groups.
• To evaluate the antibacterial efficacy of the developed photosensitizers against Gram-positive and Gram-negative bacteria.

Main Methods:

• Molecular design incorporating carbonyl groups into a donor-acceptor (D-A) system to boost SOC.
• Synthesis of two D-A photosensitizers (CTI-1-anchor and CTI-2-anchor) with membrane-anchoring functionalities.
• Measurement of ROS quantum yield and assessment of antibacterial activity against *S. aureus* and *E. coli*.

Main Results:

• The CTI-1-anchor photosensitizer achieved a high ROS quantum yield of 87%.
• CTI-1-anchor demonstrated significant antibacterial efficacy: 97.7% against *S. aureus* and 73.4% against *E. coli*.
• The membrane-anchoring groups facilitated improved bacterial surface attachment and treatment.

Conclusions:

• The molecular design strategy effectively enhances ROS quantum yield and antibacterial performance.
• The developed photosensitizers represent a promising advancement in antibacterial photodynamic therapy.
• This study provides a foundation for designing next-generation photosensitizers for combating bacterial infections.