Indocyanine green-based nanomedicine for theranostic applications

Indocyanine green (ICG), a near-infrared (NIR) fluorescent dye approved by the FDA, is widely utilized in biomedical applications due to its excellent biocompatibility, photophysical properties, and versatility in imaging and therapeutic modalities. Despite its advantages, ICG's clinical use is limited by photothermal degradation, poor solution stability, rapid in vivo clearance, and low fluorescence quantum yield. To overcome these challenges, advanced nano-delivery systems, including lipid-based, polymer-based, protein-based, inorganic-based, and carrier-free formulations, have been developed to enhance ICG's stability, circulation time, and targeting efficiency. These nanoformulations enable multimodal applications, such as NIR fluorescence imaging, photoacoustic imaging, optical coherence tomography, two-photon fluorescence imaging, photothermal therapy (PTT), photodynamic therapy (PDT), and sonodynamic therapy (SDT), across various disease models, particularly in tumor diagnosis, image-guided surgery, lymph node mapping, inflammation, and cardiovascular diseases. This review highlights recent progress in ICG-based nanomedicines, emphasizing their design, diagnostic and therapeutic capabilities, and potential for clinical translation. By addressing ICG's limitations through nanotechnology, these systems offer promising strategies for precision medicine, with opportunities for further optimization to enhance therapeutic outcomes.