Aptamer-mediated nanocomposites of semiconductor quantum dots and graphene oxide as well as their applications in intracellular imaging and targeted drug delivery

Fluorescent semiconductor quantum dot-graphene oxide (QD-GO) nanocomposites with unique optical properties can be prepared by a facile decoration of aptamer-labelled CdSe@ZnS QDs on GO nanosheets. The formation of such nanocomposites is based on the pi-pi stacking between the DNA bases on the QD surfaces and the GO. TEM and AFM were used to study the morphologies and distribution of the QDs on the GO surfaces. Steady-state fluorescence spectra, time-resolved fluorescence experiments and fluorescence imaging were employed to study the optical properties of the prepared aptamer-QD-GO nanocomposites. Furthermore, we investigate the potential applications of the nanocomposites in bio-imaging and cell-targeted drug delivery. The QDs decorated on the surfaces of GO could serve as fluorescent labeling probes for tracking the intracellular transport, while the GO combined with the aptamer conjugated on the outside of the nanocomposites facilitates the targeted drug delivery with enhanced loading capability. It is believed that the present aptamer-QD-GO nanocomposite-based nanomedicine would permit the development of more effective means for diagnosing and treating malignancies compared to the currently used methods.