Novel Near Infrared Dyes Targeting Carbonic Anhydrase IX for Fluorescence Imaging Applications

Area of Science:

• Biomedical Engineering
• Organic Chemistry
• Medical Imaging

Background:

• Carbonic anhydrase IX (CAIX) is a tumor-associated biomarker upregulated in hypoxic tumors.
• Fluorescence-guided surgery requires sensitive imaging techniques to detect residual cancer.
• Acetazolamide is a known drug that can be modified for targeted dye development.

Purpose of the Study:

• To design, synthesize, and evaluate novel CAIX-targeting fluorescent probes.
• To assess the impact of targeting moiety and fluorophore structure on imaging efficacy.
• To investigate the potential of these probes for fluorescence-guided surgery.

Main Methods:

• Synthesis of novel heptamethine cyanine-based fluorescent probes functionalized with acetazolamide derivatives.
• In vitro characterization including optical properties, binding affinities (bCAII, HSA), and cell-based assays (HT-29 cells).
• In vivo assessment of tumor targeting efficacy using Optical Imaging in a mouse xenograft model.

Main Results:

• The C8-acetazolamide (C8-AZA) targeting moiety demonstrated the highest affinity for CAIX.
• Dye1-C8-AZA exhibited superior binding affinity to bCAII and CAIX-expressing cells compared to existing probes.
• All synthesized C8-AZA probes showed high and specific tumor accumulation in vivo, often outperforming HypoxyFluor-1.

Conclusions:

• The C8-AZA targeting moiety enhances probe affinity and specificity for CAIX.
• Fluorophore structure significantly influences in vivo imaging efficacy.
• These novel CAIX-targeting probes, particularly Dye1-C8-AZA, show promise for clinical translation in tumor fluorescence imaging.