Polymethine Chromophores for NIR-II Phototheranostics: From Molecular Engineering to Nanoformulation-Enabled...

Area of Science:

• Materials Science
• Biomedical Engineering
• Chemistry

Background:

• Polymethine dyes, including cyanines, are crucial for second near-infrared window (NIR-II) bioimaging due to tunable optical properties and modular design.
• Advances in molecular engineering have expanded the range of NIR-II polymethine fluorophores, enhancing control over optical characteristics.

Purpose of the Study:

• To review progress in molecular engineering of polymethine dyes for NIR-II bioimaging.
• To discuss challenges hindering direct biological applications of these dyes.
• To highlight the role of nanoformulation in advancing polymethine dyes for imaging and theranostics.

Main Methods:

• Summarizing recent advancements in polymethine dye molecular engineering.
• Analyzing barriers to in vivo application, such as aggregation-caused quenching and photostability.
• Reviewing nanoformulation strategies to improve dye performance and enable theranostic applications.

Main Results:

• Molecular engineering has significantly improved polymethine fluorophore properties for NIR-II applications.
• Free polymethine dyes face limitations including aggregation, instability, and poor in vivo behavior.
• Nanoformulation effectively addresses these limitations, transforming dyes into versatile NIR-II imaging and theranostic platforms.

Conclusions:

• Nanoformulation is essential for translating polymethine dye potential into effective biological applications.
• Engineered polymethine dyes, when nanoformulated, offer adaptable platforms for advanced NIR-II bioimaging and theranostics.
• Further development is needed to overcome remaining challenges for clinical translation.