| The aim of this study is to develop a nano graphene–polyglycerol–curcumin hybrid capable of
simultaneous co-delivery of chemotherapeutic drug and cytotoxic heat to cancer cells by near infrared
(NIR) laser irradiation. Based on a fluorescence quenching study, the nano graphene sheet was
functionalized by a polyglycerol polymer via p–p interaction between the p conjugated system of
graphene and the aromatic focal point of polyglycerol through static mechanism. The binding constant
and standard Gibbs free energy change of the binding process, obtained from isothermal titration
calorimetry (ITC), were 1.8 106 M1 and 35.7 kJ mol1, respectively. This hybrid showed excellent
heat generation efficiency (DT z 60 C in 5 min, 1 W cm1 NIR laser) and high loading capacity of
curcumin (61%). The resulting drug delivery system displayed a good stability with low drug release in
PBS. However, NIR laser irradiation could trigger release of curcumin from the surface of the
functionalized graphene sheet in PBS (up to 5-fold greater release) due to the local generated heat. Also
the laser induced intracellular release of curcumin was confirmed by flow cytometry analysis. So the
combination of chemo/photothermal therapy using this advanced drug delivery system demonstrated
a synergistic effect for killing of MCF-7 breast cancer cells by MTT and apoptosis assays. |