A consortium of British and Chinese scientists has produced novel quantum dots that could be used in imaging, drug delivery and photothermal therapy.

Nanotechnology has had a rapidly-growing role to play in biomedical technology in the last five years. Graphene and its derivatives are being investigated for everything from biosensing to cancer therapy. Nanoparticles have been tested for use in magnetic imaging and targeted drug delivery, and quantum dots are being studied for use in fluorescent imaging.

But a collaboration between researchers in Shanghai and Sheffield may just have found a material that combines all of these properties - magnetic graphene oxide-iron oxide quantum dots (MGQDs). To be reported in an upcoming issue of Carbon [DOI: 10.1016/j.carbon.2015.06.070], these dots have the potential to be used in magnetic resonance imaging (MRI),  fluorescent imaging, targeted drug delivery and photothermal therapy.

The graphene oxide-iron oxide quantum dots in question were synthesises by dispersing graphene oxide (GO) in a solution of iron oxide precursors (IO), to make nanoparticles. These were then autoclaved to produce the final MGQDs. A common drug for skin treatment (lidocaine hydrochloride) was then loaded onto the dots, with a ratio of drug to QD of 0.31:1. Two types of cells were used to test the drug-loaded MGQDs – dermal fibroblasts (from human skin) for imaging and drug delivery, and HeLa cells for photothermal experiments.

External magnetic fields from an MRI were used to precisely manipulate the MGQDs, but without causing any residual magnetisation to the cell. Once delivered to the skin cells, the drug was found to be steadily released from the quantum dots over 8 h. For fluorescent imaging, both toxicity and luminescence were measures. The MGQDs displayed very low toxicity, while still emitting the same level of luminescence as cadmium telluride quantum dots (which are toxic to cells). And for the photothermal measurements, a near-infrared laser was used to irradiate a suspension of HeLa cells and MGQDs. This increased the temperature of the cell by ~50°C, which suggests that MGQDs could be potentially used for the ablation of tumours.

This work is ongoing, and several questions remain around the use of MGQDs, but it is hoped that this work opens a door to a novel nanosystem suitable for use in the detection, monitoring and treatment of diseases.


R. Justin, K. Tao, S. Román, D. Chen, Y. Xu, X. Geng, I.M. Ross, R.T. Grant, A. Pearson, G. Zhou, S. MacNeil, K. Sun, B. Chen - Carbon (2016) 97, 54-70, “Photoluminescent and superparamagnetic reduced graphene oxide–iron oxide quantum dots for dual-modality imaging, drug delivery and photothermal therapy.” DOI: 10.1016/j.carbon.2015.06.070