Hierarchical multifunctional graphene oxide cancer nanotheranostics agent for synchronous switchable fluorescence imaging and chemical therapy.

A nanotheranostics platform was synthesized based on PEGylated graphene oxide-gold nanoparticles and specified with aptamer toward the MUC-1-positive tumor cells. Subsequently, it was loaded with doxorubicin, used for non-invasive fluorescence imaging and therapy of breast and colon tumors. The success of the nano-coating at each synthesis step was characterized through FTIR, XRD, TGA, FE-SEM, EDAX, Zeta-potential, and fluorescence spectroscopy. Besides, the ability of the designed platform in targeted imaging, drug delivery, and in vitro therapy were evaluated using fluorescence microscopy and flow cytometry. The selected aptamer acts as a quencher, resulting in an "on/off" fluorescence biosensor. When the aptamer specifically binds to the MUC-1 receptor, its double strands separate, leading to the drug release and the recovery of the fluorescence of ("On" state) at the excitation wavelength of 300 nm. Based on cell toxicity results, this platform has more toxicity toward the MUC-1-positive tumor cells (HT-29 and MCF-7) compared  to MUC-1-negative cells (Hep-G2), representing its selective performance. Thus, this nano-platform can be introduced as a multifunctional cancer nanotheranostics system for tracing particular biomarkers, non-invasive imaging, and targeted chemotherapy. Graphical abstract.