Chalcogen Atom-Modulated Croconaine for Efficient NIR-II Photothermal Theranostics.

Area of Science:

• Biomedical Engineering
• Materials Science
• Organic Chemistry

Background:

• Organic dye-based agents are promising for cancer theranostics due to deep tissue penetration and biocompatibility.
• Developing near-infrared-II (NIR-II) absorbing dyes with optimal optical properties requires precise molecular design.
• Chalcogen atom modulation offers a strategy to tune the optical properties of organic dyes.

Purpose of the Study:

• To design and synthesize novel chalcogen atom-modulated croconaine dyes for NIR-II light-triggered photothermal theranostics.
• To investigate the effect of different chalcogen atoms (O, S, Se, Te) on the light absorption properties of croconaine.
• To evaluate the photothermal performance, biocompatibility, and theranostic potential of the developed agents.

Main Methods:

• Synthesis of croconaine derivatives with varying chalcogen atoms (O, S, Se, Te).
• Characterization of optical absorption properties, photothermal conversion efficiency, and photostability.
• Preparation and evaluation of nanoformulations (CRTe-NPs) for tumor targeting and imaging.
• In vitro and in vivo studies to assess theranostic efficacy, including cell killing and tumor elimination.

Main Results:

• Chalcogen substitution precisely regulated light absorption from NIR-I to NIR-II range via the heavy-atom effect.
• Tellurium-substituted croconaine (CRTe) exhibited superior NIR-II responsiveness, high photothermal conversion efficiency (70.6%), and good photostability.
• CRTe nanoparticles (CRTe-NPs) showed favorable tumor accumulation and enabled high-resolution, high-contrast visualization of tumor regions using NIR-II optoacoustic imaging.
• CRTe-NPs demonstrated efficient cancer cell killing and tumor elimination upon 1064 nm laser irradiation.

Conclusions:

• Chalcogen atom modulation is an effective strategy for designing NIR-II organic photothermal agents.
• CRTe and its nanoformulations show significant potential for NIR-II photothermal theranostics, combining imaging and therapeutic capabilities.
• This approach offers a promising pathway for developing advanced cancer treatment modalities.