pH-sensitive drug delivery based on chitosan wrapped graphene quantum dots with enhanced fluorescent stability.

Graphene quantum dots (GQDs) were prepared by the pyrolysis of citric acid (CA), which were used for the loading of hydrophilic cytarabine (Cyt), an anti-cancer drug, and then wrapped with chitosan (CS) gels for the encapsulation of the loaded Cyt. The fluorescent stability of GQDs was significantly enhanced in the presence of CS, which might be attributed to the inhibited agglomeration of GQDs by the CS gels. In addition, the burst release of Cyt from the developed carrier was also effectively relieved by the CS coating. Since the incorporation of Cyt into GQDs was achieved by amidation reaction, the delivery of Cyt from the carrier was pH-sensitive due to the hydrolysis of the amido linkage between GQDs and Cyt in acidic medium.