The covalent functionalization of graphene oxide (GO) with chitosan (CS) is successfully accomplished via a facile amidation process. The CS-grafted GO (GO-CS) sheets consist of about 64 wt.% CS, which imparts them with a good aqueous solubility and biocompatibility. Additionally, the physicochemical properties of GO-CS are studied. As a novel nanocarrier, GO-CS is applied to load a water-insoluble anticancer drug, camptothecin (CPT), via π-π stacking and hydrophobic interactions. It is demonstrated that GO-CS possesses a superior loading capacity for CPT, and the GO-CS-CPT complexes show remarkably high cytotoxicity in HepG2 and HeLa cell lines compared to the pure drug. At the same time, GO-CS is also able to condense plasmid DNA into stable, nanosized complexes, and the resulting GO-CS/pDNA nanoparticles exhibit reasonable transfection efficiency in HeLa cells at certain nitrogen/phosphate ratios. Therefore, the GO-CS nanocarrier is able to load and deliver both anticancer drugs and genes.

Covalently functionalized graphene sheets are prepared by grafting a welldefi ned thermo-responsive poly( N -isopropylacrylamide) (PNIPAM) via click chemistry. The PNIPAM-grafted graphene sheets (PNIPAM-GS) consist of about 50% polymer, which endows the sheets with a good solubility and stability in physiological solutions. The PNIPAM-GS exhibits a hydrophilic to hydrophobic phase transition at 33 ° C, which is relatively lower than that of a PNIPAM homopolymer because of the interaction between graphene sheets and grafted PNIPAM. Moreover, through π --π stacking and hydrophobic interaction between PNIPAM-GS and an aromatic drug, the PNIPAM-GS is able to load a water-insoluble anticancer drug, camptothecin (CPT), with a superior loading capacity of 15.6 wt-% (0.185 g CPT per g PNIPAM-GS). The in vitro drug release behavior of the PNIPAM-GS-CPT complex is examined both in water and PBS at 37 ° C. More importantly, the PNIPAM-GS does not exhibit a practical toxicity and the PNIPAM-GS-CPT complex shows a high potency of killing cancer cells in vitro. The PNIPAM-GS is demonstrated to be an effective vehicle for anticancer drug delivery.

Here we report a new type of self-powered, visible-light photodetector fabricated from thermally reduced rGO-ZnO hybrid nanostructure. The photocurrent generation of the photodetectors under zero-bias enables hybrid rGO-ZnO devices to work like photovoltaic cells, which could power themselves without electrical power input. The thermal treatment at elevated temperature not only reduces graphene oxide (GO) into reduced graphene oxide (rGO), but also dopes the ZnO nanoparticles with carbon atoms, enabling their visible-light photoresponse capability. The pronounced and fast photocurrent generation was attributed to the efficient charge transfer between the rGO and carbon-doped ZnO nanoparticles, which were in intimate contact. The efficient charge transfer of the rGO-ZnO hybrid nanostructures also indicates that there could be applications in other light energy harvesting devices, including solar cells, sensors and visible-light photocatalysis.

We present a novel approach to the fabrication of advanced polymeric nanocomposites from poly(vinyl alcohol) (PVA) by incorporation of PVA-grafted graphene oxide. In this work, we have synthesized PVA-grafted graphene oxide (PVA-g-GO) for the strong interfacial adhesion of graphene oxide (GO) to the PVA matrix. It was found that the mechanical properties of PVA were greatly improved by incorporating PVA-g-GO. For example, the tensile strength and Young's modulus of the PVA nanocomposite films containing 1 wt % net GO in the PVA-g-GO significantly increased by 88 and 150%, respectively, as compared to unfilled PVA. The elongation at break was also increased by 22%, whereas the GO/PVA nanocomposite containing 1 wt % pristine GO was decreased by 15%. Therefore, the presence of the PVA-g-GO in the PVA matrix could make the PVA not only stronger but also tougher. The strong interfacial adhesion between PVA-g-GO and the PVA matrix was attributed to the good compatibility between PVA-g-GO and the matrix PVA as well as the hydrogen-bonding between them.

With the depletion of conventional energy sources, the demand for renewable energy and energy-efficient devices continues to grow. As a novel 2D nanomaterial, graphene attracts considerable research interest due to its unique properties and is a promising material for applications in energy conversion and storage devices. Recently, the fabrication of fuel cells and solar cells using graphene for various functional parts has been studied extensively. This research news summarizes and compares the advancements that have been made and are in progress in the utilization of graphene-based materials for energy conversion.