Shortwave-Infrared Fluorescent Molecular Imaging Probes Based on π-Conjugation Extended Indocyanine Green

Recently, shortwave-infrared (SWIR) fluorescence imaging for the optical diagnostics of diseases has attracted much attention as a new noninvasive imaging modality. For this application, the development of SWIR molecular imaging probes with high biocompatibility is crucial. Although many types of biocompatible SWIR fluorescent probes based on organic dyes have been reported, there are no SWIR-emitting molecular imaging probes that can be used for the detection of specific biomolecules in vivo. To apply SWIR-emitting molecular imaging probes to biomedical fields, we developed a biocompatible SWIR fluorescent dye based on pi-conjugation extended indocyanine green (ICG), where ICG is the only approved near-infrared dye by the US Food and Drug Administration (FDA) for use in the clinic. Using the pi-conjugation extended ICG, we prepared SWIR molecular imaging probes that can be used for in vivo tumor imaging. Herein, we demonstrate noninvasive SWIR fluorescence imaging of human epidermal growth factor receptor 2 (HER2)-positive and epidermal growth factor receptor (EGFR)-positive breast tumors using pi-conjugation extended ICG and monoclonal antibody conjugates. The presented pi-conjugation extended ICG analog probes will be a breakthrough to apply SWIR fluorescence imaging in biomedical fields.

Automated summary

SWIR fluorescence imaging using high biocompatible molecular probes is a new noninvasive imaging modality. Development of biocompatible SWIR fluorescent dyes, based on pi-conjugation extended ICG, provides breakthrough for in vivo tumor imaging. This technology has potential applications in biomedical fields.