Dual fluorescence nano-conjugates based on gold nanoclusters for tumor-targeting imaging

The unique properties of gold nanoclusters (Au NCs) enable them to be functionalized as fluorescent probes or pro-drugs for biomedical application. A facile approach was introduced to synthesize nanoconjugates (Au–cRGD–MPA), which was composed of Au NCs, cyclic (Arg–Gly–Asp–DTyr–Lys) (cRGD) peptide and a near infrared (NIR) fluorescence dye (MPA). The nanoconjugates exhibited dual fluorescence in the visible range and NIR range simultaneously. The low cytotoxicity of Au–cRGD–MPA was demonstrated in MCF-7 cell line and U87 cell line. The cell affinity investigations verified the outstanding tumor-targeting capability of Au–cRGD–MPA for tumor cells. The biodistribution characteristics and tumor targeting ability of the probes were elucidated in normal nude mice and tumor-bearing mice, respectively. Attributing to the small size (less than 5 nm), the majority of the nanoconjugates metabolized from the living subjects via the kidney-bladder pathway. Additionally, Au–cRGD–MPA displayed favorable tumor-specificity in Integrin αvβ3 over-expressed tumor-bearing (MDA-MB-231) mice. Consequently, the results demonstrated that the dual fluorescence probe is a promising candidate for tumor imaging and disease treatment monitoring.