Multifunctional Hybridized Local and Charge-Transfer Small Molecular Fluorophore for Imaging-Guided Photodynamic...

Area of Science:

• Materials Science
• Photochemistry
• Biomedical Engineering

Background:

• Designing single agents with both fluorescence and reactive oxygen species (ROS) generation is challenging.
• Existing phototherapeutic agents often lack dual functionality for imaging and therapy.

Purpose of the Study:

• To rationally design and synthesize a novel fluorophore (XSOTA) with integrated fluorescence and ROS generation capabilities.
• To investigate the photophysical properties and potential applications of XSOTA in bioimaging and photodynamic therapy.

Main Methods:

• Synthesis of XSOTA by linking dibenzothiophene-S,S-dioxide acceptor to triphenylamine donor via a vinyl bridge.
• Characterization of photophysical properties including fluorescence quantum yield, two-photon absorption cross-section, and ROS yield.
• Encapsulation of XSOTA into nanoparticles for in vivo studies.
• Evaluation of deep-tissue two-photon fluorescence imaging in mouse vasculature.
• Assessment of imaging-guided photodynamic therapy efficacy in tumor suppression.

Main Results:

• XSOTA exhibits hybridized local and charge transfer (HLCT) excited-state character, enabling dual photophysical functions.
• Achieved high fluorescence quantum yield (89.2%), large two-photon absorption cross-section (7000 GM), and high ROS yield (56.3%).
• Demonstrated deep-tissue imaging up to 350 µm in mouse liver tissue.
• Showed significant tumor growth suppression via imaging-guided photodynamic therapy with no observable organ toxicity.

Conclusions:

• HLCT-based fluorophores like XSOTA are promising dual-function agents for image-guided photodynamic cancer therapy.
• The rational design strategy provides a pathway for developing advanced phototherapeutic agents.
• XSOTA demonstrates significant potential for clinical translation in cancer treatment and diagnostics.