Surgeons must rely on their naked eye and experience during often-lengthy procedures to avoid sensitive glands and tissues. Also they must depend on biopsy results to determine if the diseased tissue has been removed. Molecular modalities imaging such as SPECT/PET, MRI, and ultrasound give good preoperative images, but cannot be used intraoperatively. Optical imaging requires highly selective fluorophores which can target specific tissue. Fluorophores in the near infrared window (650-900 nm) offer improved tissue penetration. The two fundamental unsolved problems in optical imaging are the nonspecific uptake of near-infrared (NIR) fluorophores by normal tissues and organs, and the incomplete elimination of unbound targeted fluorophores from the body. Novel zwitterionic NIR fluorophores having net charges of -4, -2, 0, +2, and +4 were synthesized and their performance as a function of charge distribution, hydrophilicity/lipophilicity and receptor-based targeting for image-guided surgery were evaluated in comparison to known compounds such as the FDA approved contrast agent ICG. These zwitterionic NIR fluorophores have ideal optical properties, including emission at about 700 nm and 800 nm, elevated extinction coefficients, and high quantum yields in serum. NIR fluorophores were injected intravenously into mice and rats, and their bio-distribution and clearance were measured.

Design and synthesis of water-soluble NIR contrast agents for In vivo optical imaging

256th National Meeting (2018)

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