A novel water-soluble NIR-II cyanine dye for fast targeted through-skull fluorescence imaging of orthotopic glioma.

A novel NIR-II cyanine dye denoted as Sulfo-1100 was designed and synthesized to realize high-fidelity in vivo imaging of orthotopic glioma. The dye in FBS (10%) and PBS showed NIR-I absorptions (866 nm and 776 nm, respectively) and NIR-II fluorescence emissions (1114 nm and 1120 nm). To realize specific imaging for orthotopic glioma in vivo, Sulfo-1100 was assembled with holo-Tf to form hT-Sulfo-1100 nanoparticles (NPs). They showed excellent targeting and through-skull imaging ability in as soon as 10 min. More importantly, hT-Sulfo-1100 NPs and free Sulfo-1100 could be excreted through the renal clearance pathway within 12 h and were retained neither in the liver nor spleen, avoiding a long-term toxicity risk. This novel water-soluble NIR-II fluorescent dye offers a tool for deep-tissue through-skull in situ imaging to detect tumors with high optical resolution and good biocompatibility.