NIR-II Excitable Water-Dispersible Two-Dimensional Conjugated Polymer Nanoplates for In Vivo Two-Photon Luminescence...

Area of Science:

• Materials Science
• Biomedical Engineering
• Optics

Background:

• Two-dimensional conjugated polymers (2DCPs) show potential for two-photon luminescence (TPL) bioimaging.
• Developing TPL agents excitable in the second near-infrared window (NIR-II) remains challenging.

Purpose of the Study:

• To design and synthesize novel 2DCPs for NIR-II excited TPL bioimaging.
• To investigate the exfoliation and photophysical properties of these 2DCPs.
• To evaluate their efficacy for in vivo bioimaging.

Main Methods:

• Synthesis of octupolar, olefin-linked 2DCPs with donor-acceptor structures and aggregation-induced emission (AIE) properties.
• Exfoliation of 2DCP1 into water-dispersible nanoplates using a temperature-swing method with Pluronic F-127.
• Characterization of two-photon absorption cross-section (2PACS) and photoluminescence quantum yield (PLQY).
• In vivo imaging of mouse brain vasculature using 2DCP1 nanoplates.

Main Results:

• Developed 2DCP1 and 2DCP2 with high NIR-II two-photon absorption (2PACS ~64.0 GM).
• Exfoliated 2DCP1 nanoplates exhibited reduced 2PACS but significantly enhanced PLQY (33.3%).
• Achieved deep-tissue (421 μm) visualization of mouse brain vasculature in vivo with good contrast.

Conclusions:

• Novel 2DCPs are effective for NIR-II excited TPL bioimaging.
• Exfoliation significantly impacts the photophysical properties of 2DCPs.
• These findings provide a foundation for developing advanced NIR-II TPL bioimaging agents.