NIRII‐HDs: A Versatile Platform for Developing Activatable NIR‐II Fluorogenic Probes for Reliable In Vivo Analyte Sensing

Abstract

Small‐molecule‐based second near‐infrared (NIR‐II) activatable fluorescent probes can potentially provide a high target‐to‐background ratio and deep tissue penetration. However, most of the reported NIR‐II activatable small‐molecule probes exhibit poor versatility owing to the lack of a general and stable optically tunable group. In this study, we designed NIRII‐HDs, a novel dye scaffold optimized for NIR‐II probe development. In particular, dye NIRII‐HD5 showed the best optical properties such as proper pKa value, excellent stability, and high NIR‐II brightness, which can be beneficial for in vivo imaging with high contrast. To demonstrate the applicability of the NIRII‐HD5 dye, we designed three target‐activatable NIR‐II probes for ROS, thiols, and enzymes. Using these novel probes, we not only realized reliable NIR‐II imaging of different diseases in mouse models but also evaluated the redox potential of liver tissue during a liver injury in vivo with high fidelity.

Recent Progress of Cyanine Fluorophores for NIR‐II Sensing and Imaging

“…Using these novel probes, we not only achieved reliable NIR-II imaging of different diseases, but also assessed the redox potential of liver tissue during liver injury in vivo with high fidelity. [40] 3.3. NIR-II imaging based on cyanine fluorophores NIR-II biological imaging based on the reported cyanine fluorophores can be divided into three categories: NIR-II vascular and organ imaging, tumor diagnosis imaging, imagingguided surgery or therapy.…”

Synthesis of Silicon-Substituted Hemicyanines for Multimodal SWIR Imaging

“…The ability to substitute the endocyclic oxygen atom with a SiMe 2 group and to vary the donor in the final step was instrumental in achieving SWIR absorbance. Indeed, SWIR-HD is the most red-shifted hemicyanine developed to date. , In the context of activity-based sensing probe development, computational studies indicate that the SWIR properties ( e.g. , λ abs ) would be retained if one ethyl group on the aniline was removed to mimic an “uncapped” probe (Figure S13).…”

Synthesis of silicon-substituted hemicyanines for multimodal SWIR imaging

“…Of note, complementary remodeling efforts have yielded PA and NIR-II analogs. 16,17 However, in the present study, we selected this platform owing to its relatively small size and ease of conversion into activity-based sensing probes. 16,[18][19][20][21][22][23] Unfortunately, these favourable properties come at a cost because HDs are essentially truncated cyanines which are blue shifted by ~100 nm.…”