Gold Nanoclusters–Indocyanine Green Nanoprobes for Synchronous Cancer Imaging, Treatment, and Real-Time Monitoring Based on Fluorescence Resonance Energy Transfer

Well-designed gold nanoclusters–indocyanine green nanoprobes (Au NCs–INPs) have been developed by the conjugation of Au NC assemblies with indocyanine green (ICG) for the therapeutic real-time monitoring based on fluorescence resonance energy transfer (FRET). The synthesized Au NCs–INPs demonstrated the improved cellular uptake and effective tumor targeting because of the enhanced permeability and retention effect and the gp60-mediated secreted protein acidic and rich in cysteine combined transport pathway, suggesting excellent dual-modal near-infrared fluorescence and photoacoustic imaging. Moreover, the simultaneous photodynamic therapy (PDT) and photothermal therapy (PTT) of Au NCs–INPs exhibited higher cancer cell killing and tumor removal efficiency than those of PDT or PTT alone. More importantly, a promising therapeutic monitoring strategy was performed based on FRET between Au NCs and ICG, suggesting that Au NCs–INPs could be utilized to evaluate the therapeutic response by real-time monitoring the change in Au NCs in fluorescence intensity together with ICG supersession. Therefore, Au NCs–INPs as a novel photosensitizer have great potentials for combined tumor imaging, therapy, and therapeutic monitoring in real time.