Polyethylenimine-Grafted Graphene Oxide As An Efficient Gene Delivery Vector

Gene therapy is a promising approach for treating diseases caused by genetic disorders such as cystic fibrosis, Parkinson's disease, and cancers. Successful gene therapy requires a vector that protects DNA from nuclease degradation and facilitates cellular uptake of DNA into cells with improved transfection efficiency. Nonviral vectors such as liposomes, polymers and nanomaterials (for examples, gold nanoparticles, silica nanoparticles, and carbon nanotubes) have been intensively investigated for DNA delivery.Recently, graphene, a novel class of 2D carbon-based nanomaterial, has recieved more and more attention in rencent years due to its unique electrical, thermal, and mechanical properties. Meanwhile, graphene oxide (GO) has been successfully used in biological applications including for drug delivery, cellular imaging, photothermal therapy, and biosensors. GO offers several distinct advantages over other nonviral vectors. First of all, GO is obtained by oxidation of graphite, and therefore contains many hydroxyl, carboxylic acid and other reactive groups amenable for chemical modifications, rendering GO tailored for a range of biomedical and other applications. Secondly, GO possesses good biocompatibility due to its rich hydrophilic groups. In addition, production of GO can be achieved in a convenient, inexpensive and scaleble way. Pristine GO can not effectively adsorb double-stranded DNA (dsDNA) that will restrict the application of GO in gene delivery.In this paper, we show that GO grafted with positively charged polyethylenimine (PEI) allows condensation of plasmid DNA onto the surface of GO sheet through electrostatic interaction arising from the cationic PEI. Furthermore, we demonstrated that polyethylenimine-grafted graphene oxide (PEI-GO) is able to deliver plasmid DNA into cells. Therefore the current work may provide significant insight into development of efficient novel gene delivery systems based on GO.