Click Synthesis Enabled Sulfur Atom Strategy for Polymerization-Enhanced and Two-Photon Photosensitization

Area of Science:

• Materials Science
• Photochemistry
• Biomedical Engineering

Background:

• Advanced photosensitizers (PSs) are crucial for expanding photodynamic therapy (PDT) applications.
• Tailoring PSs with enhanced properties, such as improved intersystem crossing (ISC), is a key research area.

Purpose of the Study:

• To develop novel sulfur atom-based photosensitizers using a catalyst-free thiol-yne click reaction.
• To enhance the intersystem crossing (ISC) efficiency through the sulfur "heavy atom effect" and polymerization.
• To create a donor-π-acceptor (D-π-A) molecular system with aggregation-induced emission (AIE) properties for improved two-photon excitation PDT.

Main Methods:

• Utilized a catalyst-free thiol-yne click reaction for PS synthesis.
• Incorporated sulfur atoms to leverage the "heavy atom effect" for enhanced ISC.
• Introduced a tetraphenylpyrazine-based aggregation-induced emission (AIE) unit to suppress non-radiative decay.
• Fabricated polymer nanoparticles for in vitro studies.

Main Results:

• Successfully synthesized sulfur atom-based PSs with enhanced ISC via the "heavy atom effect" and polymerization.
• Demonstrated that the AIE unit effectively suppressed non-radiative decay, further facilitating ISC in aggregated states.
• Created a D-π-A molecular system exhibiting efficient two-photon excitation properties.
• Achieved high singlet oxygen generation efficiency with the fabricated polymer nanoparticles.

Conclusions:

• The developed polymer nanoparticles show excellent in vitro two-photon-excited PDT efficacy against cancer cells.
• The combination of sulfur "heavy atom effect", polymerization, and AIE units offers a promising strategy for advanced PS design.
• These findings indicate significant potential for deep-tissue disease therapy using the novel PSs.