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Applications of reduced graphene oxide (rGO) in epoxy (EP) anticorrosion coatings are hindered by its poor dispersibility and galvanic corrosion hazard with the metal matrix. With an excellent water dispersibility, the acid-treated g-C3N4 nanosheets (CNNS) can be physically combined with rGO through ultrasonic treatment so as to enhance the dispersion of rGO in waterborne epoxy. The structure and morphology of the new hybrids prepared by this simple ultrasonic treatment were characterized through FTIR, Raman, XRD, XPS, and TEM. The results show that the best anticorrosion performance of the coating is achieved in 0.5 M sulfuric acid when the mass ratio of CNNS and rGO in the hybrid is 1:5. Compared with the case of pure EP coating, the corrosion current density of the new hybrid decreases by one order of magnitude, and electrochemical impedance increases by nearly two orders of magnitude. The new CNNS@rGO hybrid prepared by a simple ultrasonic method has broad prospects in the field of waterborne epoxy resin anticorrosive coatings. [ABSTRACT FROM AUTHOR]

Macrocyclic chelators have been widely employed in the realm of nanoparticle-based positron emission tomography (PET) imaging, whereas its accuracy remains questionable. Here, we found that 64Cu can be intrinsically labeled onto nanographene based on interactions between Cu and the π electrons of graphene without the need of chelator conjugation, providing a promising alternative radiolabeling approach that maintains the native in vivo pharmacokinetics of the nanoparticles. Due to abundant π bonds, reduced graphene oxide (RGO) exhibited significantly higher labeling efficiency in comparison with graphene oxide (GO) and exhibited excellent radiostability in vivo. More importantly, nonspecific attachment of 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) on nanographene was observed, which revealed that chelator-mediated nanoparticle-based PET imaging has its inherent drawbacks and can possibly lead to erroneous imaging results in vivo. [ABSTRACT FROM AUTHOR]

A novel β -cyclodextrin (β -CD) modified graphene oxide (CDGO) membrane with large adsorption capacity and high flux is developed for efficient removal of bisphenol A (BPA), which is an environmental endocrine disruptor that can affect human health. The CDGO membranes are fabricated by stacking CDGO nanosheets on porous substrates via vacuum filtration, and the CDGO nanosheets are fabricated by chemically grafting β -CD molecules onto both sides of GO nanosheets. Because β -CD molecules can form stable complexes with BPA molecules through host-guest recognition, the proposed CDGO membranes are featured with high efficiency for BPA removal. The water fluxes through CDGO membranes increase linearly with increasing the operating pressure, which confirms the CDGO membrane structures are stable during operations. With BPA rejection efficiency of about 100%, the fluxes of our CDGO membranes are one or two order of magnitudes higher than those of the RO and NF membranes previously used for BPA removal. The BPA adsorption capacities of our CDGO membranes are several times higher than those of the affinity membranes previously used for BPA removal, due to the high grafting density of β -CD molecules on both sides of CDGO nanosheets, the enormous surface areas of CDGO nanosheets and the winding 2D nanochannels in CDGO membranes. Furthermore, the CDGO membranes can be regenerated easily by washing with ethanol, and the BPA removal efficiency can be recovered back to nearly 100% even after several repeated running cycles. The proposed membranes with high flux and large adsorption capacity are highly promising in applications in the field of water treatments and molecular separations. Image 1 • A novel β -CD-modified graphene oxide membrane is developed for removal of bisphenol A from water. • The fabricated membrane is featured with both large adsorption capacity and high flux. • The membrane microstructure is stable during operations under different operation pressures. • The membrane can be easily regenerated by washing with ethanol. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simple, low-energy and scalable one-step chemical expansion of graphene. • High-yield (>90%) preparation of of nanocrystalline chemically expanded graphene. • Specific capacity of 283.8F·g−1 at 1 A·g−1, and excellent rate capability. • Excellent capacity retention of ≈87% after 5000 cycles at 20 A·g−1. High-performance electrode materials are particularly important for the next-generation of supercapacitors with enhanced specific capacity and cycle stability. In this study, a simple and scalable thermal expansion method is used to convert acidic graphite oxide (AGO) into chemically expanded graphene (CEG) nanostructure, with a honeycomb morphology consisting of 2–3 graphene layers. The CEG produced by the thermal expansion of AGO under modified conditions of time and duration (CEG-2) exhibits a substantially large specific surface area of around 388 m2·g−1, in comparison to value of 6 m2·g−1 recorded on the virgin superconducting graphite powder. This provides the CEG-2 material with an excellent specific capacitance of 283.8F·g−1, recoded at 1 A·g−1. The cycle stability of CEG-2 is characterized to be highly desirable with a retention rate of around 87% after 5000 cycles. The results obtained suggest the enhanced electrochemical performance of CEG. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries face challenges including volume expansion, slow reaction kinetics, and shuttle effects. To overcome these limitations, we utilized a combination of vanadium–based heterostructures and conductive porous reduced graphene oxide aerogels to improve charge transfer kinetics. The researchers synthesised vanadium–based reduced graphene oxide aerogels (VO 2 /VS 4 @RGO) via tube furnace calcination and a one–step hydrothermal method. Vanadium–based heterostructures were electrostatically adsorbed onto the surface of three–dimensional reduced graphene oxide aerogels. The fibrous structure of VO 2 /VS 4 promoted charge transfer, while the high conductivity of V S bonds lowered the surface reaction barrier. The VO 2 /VS 4 @RGO–3/S cathode exhibited outstanding cycling stability at a high discharge rate of 2C, demonstrating an initial discharge specific capacity of 771.94 mAh g−1 and an average decay rate of 0.071 % after 700 cycles. It also maintained excellent electrochemical performance under high sulfur loading. [Display omitted] • High initial discharge specific capacity • The presence of the VO 2 /VS 4 heterostructure significantly improves the adsorption capacity and catalytic properties towards LiPS. • the graded porous structure of the aerogel effectively suppressed the volume expansion of sulfur during cycling. • At high sulfur loading, the battery demonstrated exceptional cycling reversibility. [ABSTRACT FROM AUTHOR]

• This paper presents a comprehensive overview of technologies for GO membrane preparation. • Two mainstream ion separation mechanism of GO membrane is systematacially discussed. • Functional modifications applied to GO membranes are discussed, and their respective merits and limitations are critically evaluated. • The application of GO membrane in various membrane separation techniques is summarized. • The key issues for the imminent challenge faced by GO membranes in ion sieving and prospects for impending research are highlighted. Seawater salt ion sieving and rejection achieved through membrane separation is inevitable as the human development to obtain fresh water or pure salt. Recently, graphene oxide (GO) membrane with unique physicochemical properties and adjustable structure has unique advantages in seawater desalination. In this paper, we briefly review the development of the GO membranes for seawater salt ion sieving and rejection including the preparation process, ion sieving mechanism, and physical/chemical functional modification of the GO membranes. We compare the current research status of various membrane separation technologies in different application areas and identify potential future research directions. This article aims to offer researchers ideas for the preparation and application of GO membranes, with a focus on developing green and cost-effective manufacturing processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solvent-free and low-temperature synthesis of chemically expanded graphene. • Scalable preparation of chemically expanded graphene incorporated with PANI. • High electrical conductivity of CEG-PANI (1: 0.2) nanocomposite at 393.70 S·m−1. • Enhanced specific capacity of 664 mAh·g−1 at 0.2 A·g−1 after 150 cycles. • Enhanced cycling stability of 253 mAh·g−1 after 350 cycles at 2000 mA·g−1. A simple and solvent-free approach is proposed to prepare graphene nanonetwork-polyaniline (PANI) nanocomposite with enhanced electrical conductivity and Li-ion storage performance. To this end, acidic graphene oxide (AGO) and PANI are ball-milled followed by low-temperature chemical expansion leading to the formation of chemically expanded graphene (CEG) in the form of mesoporous nanonetworks with the lattice layer spacing of 0.362 nm embedded with PANI nanoparticles. CEG-PANI nanocomposite outperforms CEG, exhibiting a specific reversible capacity of 664 mAh·g−1 at 200 mA·g−1 after 150 cycles, and the discharge capacity of 253 mAh·g−1 after 350 cycles at 2000 mA·g−1. The enhanced electrochemical performance of CEG-PANI can be attributed to its large specific surface area, mesoporous structure and conductive homogeneous graphene nanonetwork doped with of N heteroatoms embedded with polyaniline, providing sufficient active sites for facile Li-ion storage. Nanostructured CEG-PANI is a promising candidate for anode of Li-ion batteries. [ABSTRACT FROM AUTHOR]

Transition metal nanocluster graphene composite exhibits better performance in energy storage materials than heteroatom graphene composite. In catalytic function separator materials for lithium-sulfur batteries, the introduction of functionalized graphene into asymmetric separators effectively seals and anchors soluble polysulfides, largely mitigating the notorious "shuttle effect". Here, we report the development of a novel asymmetric domain-limited electrochemical (ALE) exfoliation of graphite foils (natural-scaled graphite) to prepare Co-nanocluster graphene composite nanosheets (labeled as Co-G). Co-G has a large lateral size, many surface folds, and few intrinsic defects (I D /I G = 0.38). Co-nanocluster graphene composite promotes redox kinetic conversion, and its high electronic conductivity allows it to act as a second collector, accelerating charge transfer, improving the utilization of active material, and increasing cyclic stability. A lithium-sulfur battery incorporating a Co-G modified separator achieved an initial discharge capacity of 1315.5 mAh/g at 0.5 C with excellent multiplicity performance (932.3 mAh/g specific capacity at 2 C multiplicity) and cycling stability (848.4 mAh/g after 400 cycles). The asymmetric domain-limited electrochemical (ALE) method is a viable approach to the preparation of catalytic function separator materials for lithium-sulfur batteries that will have high magnification and high cyclic stability. • Preparation of transition metal graphene composites by ALE method. • Enhanced anchoring to polysulfides. • Homogeneous active sites for accelerated conversion of polysulfide species. [ABSTRACT FROM AUTHOR]

How graphene oxide (GO) derivatives might affect the cell cycle has been rarely studied. Herein, a GO derivative was fabricated by functionalization of GO with polyethylene glycol (PEG) and polyethylenimine (PEI), and its cytotoxic mechanism was investigated in-depth. It was found that our obtained GO-PEG-PEI nanosheets, not the cytotoxic coating polymer PEI, could induce defect in S phase of the mammalian cell cycle, resulting in decreased DNA synthesis, S phase arrest, and abnormal cytoskeleton structure. Further analysis demonstrated that this damaging effect on S phase could be detected in all five tested mammalian cell lines. Even at seemingly safe concentration (∼90% cells viable), GO-PEG-PEI could still induce S phase defect. Detailed investigations revealed that GO-PEG-PEI could cause genomic DNA damage, activating the intra-S-phase checkpoint control via both the ATM and the ATR signaling pathways. Our work unveils the signaling pathways involved in the interaction of GO-PEG-PEI with mammalian cells, and highlights the necessity and importance of comprehensive investigations of the effects of nanomaterials on cellular pathways, such as the cell cycle in this case, even for those with seemingly little/low cytotoxicity during preliminary evaluations. Our work also highlights the critical roles of surface chemistry in biological effects of nanomaterials. [ABSTRACT FROM AUTHOR]

Angiogenesis, i.e. the formation of neovasculatures, is a critical process during cancer initiation, progression, and metastasis. Targeting of angiogenic markers on the tumor vasculature can result in more efficient delivery of nanomaterials into tumor since no extravasation is required. Herein we demonstrated efficient targeting of breast cancer metastasis in an experimental murine model with nano-graphene oxide (GO), which was conjugated to a monoclonal antibody (mAb) against follicle-stimulating hormone receptor (FSHR). FSHR has been confirmed to be a highly selective tumor vasculature marker, which is abundant in both primary and metastatic tumors. These functionalized GO nano-conjugates had diameters of ∼120 nm based on atomic force microscopy (AFM), TEM, and dynamic laser scattering (DLS) measurement. 64 Cu was incorporated as a radiolabel which enabled the visualization of these GO conjugates by positron emission tomography (PET) imaging. Breast cancer lung metastasis model was established by intravenous injection of click beetle green luciferase-transfected MDA-MB-231 (denoted as cbgLuc-MDA-MB-231) breast cancer cells into female nude mice and the tumor growth was monitored by bioluminescence imaging (BLI). Systematic in vitro and in vivo studies have been performed to investigate the stability, targeting efficacy and specificity, and tissue distribution of GO conjugates. Flow cytometry and fluorescence microscopy examination confirmed the targeting specificity of FSHR-mAb attached GO conjugates against cellular FSHR. More potent and persistent uptake of 64 Cu-NOTA-GO-FSHR-mAb in cbgLuc-MDA-MB-231 nodules inside the lung was witnessed when compared with that of non-targeted GO conjugates ( 64 Cu-NOTA-GO). Histology evaluation also confirmed the vasculature accumulation of GO-FSHR-mAb conjugates in tumor at early time points while they were non-specifically captured in liver and spleen. In addition, these GO conjugates can serve as good drug carriers with satisfactory drug loading capacity (e.g. for doxorubicin [DOX], 756 mg/g). Enhanced drug delivery efficiency in cbgLuc-MDA-MB-231 metastatic sites was demonstrated in DOX-loaded GO-FSHR-mAb by fluorescence imaging. This FSHR-targeted, GO-based nanoplatform can serve as a useful tool for early metastasis detection and targeted delivery of therapeutics. [ABSTRACT FROM AUTHOR]

Whether graphene and graphene oxide (GO) would affect the activities of bacteria has been under debate. Nevertheless, how graphene derivatives with biocompatible coatings interact with microorganisms and the underlying mechanisms are important issues for nanobiotechnology, and remain to be further explored. Herein, three new types of nano-GOs functionalized with polyethylene glycol (nGO-PEGs) were synthesized by varying the PEGylation degree, and their effects on Escherichia coli ( E. coli ) were carefully investigated. Interestingly, nGO-PEG (1:1), the one with relatively lower PEGylation degree, could significantly stimulate bacterial growth, whereas as-made GO and the other two nGO-PEGs showed no effect. Further analysis revealed that nGO-PEG (1:1) treatment significantly accelerated FtsZ-ring assembly, shortening Phase 1 in the bacterial cell cycle. Both DNA synthesis and extracellular polymeric substance (EPS) secretion were also dramatically increased. This unique phenomenon suggests promising potentials in microbial engineering as well as in clinical detection of bacterial pathogens. As a proof-of-concept, nGO-PEG (1:1) treatment could remarkably enhance (up to 6-fold) recombinant protein production in engineered bacteria cells. To our best knowledge, this is the first demonstration of functionalized GO as a novel, positive regulator in microbial engineering. Moreover, our work highlights the critical role of surface chemistry in modulating the interactions between nanomaterials and microorganisms. [ABSTRACT FROM AUTHOR]

Nano-graphene and its derivatives have attracted great attention in biomedicine, including their applications in cancer theranostics. In this work, we develop 131I labeled, polyethylene glycol (PEG) coated reduced nano-graphene oxide (RGO), obtaining 131I-RGO-PEG for nuclear imaging guided combined radiotherapy and photothermal therapy of cancer. Compared with free 131I, 131IRGO- PEG exhibits enhanced cellular uptake and thus improved radio-therapeutic efficacy against cancer cells. As revealed by gamma imaging, efficient tumor accumulation of 131I-RGO-PEG is observed after its intravenous injection. While RGO exhibits strong near-infrared (NIR) absorbance and could induce effective photothermal heating of tumor under NIR light irradiation, 131I is able to emit high-energy X-ray to induce cancer killing as the result of radio ionization effect. By utilizing the combined photothermal therapy and radiotherapy, both of which are delivered by a single agent 131IRGO- PEG, effective elimination of tumors is achieved in our animal tumor model experiments. Toxicology studies further indicate that 131I-RGO-PEG induces no appreciable toxicity to mice at the treatment dose. Our work demonstrates the great promise of combing nuclear medicine and photothermal therapy as a novel therapeutic strategy to realize synergistic efficacy in cancer treatment. [ABSTRACT FROM AUTHOR]

Although graphene oxide (GO) has recently been considered as a highly attractive nanomaterial for future cancer imaging and therapy, it is still a major challenge to improve its in vivo tumor active targeting efficiency. Here in this full article, we demonstrated the successful and significantly enhanced in vivo tumor vasculature targeting efficacy of well-functionalized GO nanoconjugates by using vascular endothelial growth factor 121 (VEGF121) as the targeting ligand. As-developed GO nanoconjugate exhibits excellent in vivo stability, specific in vitro and in vivo vascular endothelial growth factor receptor (VEGFR) targeting, significantly enhanced tumor accumulation (>8 %ID/g) as well as high tumor-to-muscle contrast, showing great potential for future tumor targeted imaging and therapy. [ABSTRACT FROM AUTHOR]

Efficient and safe gene transfection carriers, especially for hard-to-transfect cells, are urgently demanded in basic biological research and gene therapy applications. Many insect cell lines widely used in molecular cell biology exhibit relatively low transfection efficiencies when treated by conventional non-viral agents. Herein, we develop a novel gene delivery vector by coating graphene oxide (GO) with both polyethylene glycol (PEG) and polyethylenimine (PEI), obtaining a dual-polymer-functionalized nanoscale GO (nGO-PEG-PEI) to transfect insect cells. While exhibiting remarkably reduced cytotoxicity compared with PEI, nGO-PEG-PEI, when used as the plasmid DNA transfection agent to treat Drosophila S2 cells, offers ≈7-fold and ≈2.5-fold higher efficiency compared with those achieved by using bare PEI and Lipofectamine 2000, a widely used commercial transfection agent, respectively. Interestingly, the advantages of nGO-PEG-PEI are even more dramatic when transfecting cells with lower-quality linearized DNA. It is revealed that nGO-PEG-PEI/pDNA complexes enter insect cells via a unique pathway working even at a low temperature, rather different from their entry into mammalian adherent cells. Our results encourage the development of nano-GO-based gene carriers to treat special types of hard-to-transfect cells (e.g., insect cells), and indicate that nanomaterials would enter cells by cell-type-dependent mechanisms, which merit significantly more future attentions. [ABSTRACT FROM AUTHOR]

• Novel 3D nanocomposite RGO/AgNWs/AgNPs was synthesized for electrochemical sensing. • Synergistic effect exists among RGO, AgNWs and AgNPs. • Nanocomposite is integrated with SPCE for simultaneous detection of DA, UA and EST. • The sensor exhibits superior electrocatalytic activity and outstanding selectivity. • Effective determination of Dopamine, Uric Acid and Estriol in urine samples. A facile and efficient electrochemical biosensing platform based on screen printed carbon electrode (SPCE) modified with three-dimensional (3D) nanocomposite consists of reduced graphene oxide (RGO) with the insertion of silver nanowires (AgNWs) followed by the anchoring of silver nanoparticles (AgNPs) is constructed as RGO/AgNWs/AgNPs/SPCE for the simultaneous determination of dopamine (DA), uric acid (UA) and estriol (EST). The morphology characteristic and surface elemental composition of RGO/AgNWs/AgNPs nanocomposite are investigated by field-emission scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscope. Cyclic voltammetry, electrochemical impedance spectroscopy, linear sweep voltammetry and differential pulse voltammetry are utilized to explore the electrochemical performances of the constructed electrodes. Due to abundant active sites and excellent electrocatalytic activity of the nanocomposite, the RGO/AgNWs/AgNPs/SPCE sensor exhibits well-resolved oxidation peaks and enhanced oxidation peak currents in the ternary mixture of DA, UA and EST with respective linear response ranges of 0.6 to 50 μM, 1 to 100 μM and 1 to 90 μM and detection limits (S/N = 3) of 0.16 μM, 0.58 μM and 0.58 μM, respectively. Moreover, the constructed biosensor exhibits good selectivity, reproducibility and stability, and excellent performance in determining DA, UA and EST in synthetic urine samples with excellent recovery. The results reveal that the RGO/AgNWs/AgNPs nanocomposite is a promising candidate for advanced electrode material in electrochemical sensing field and possesses great application prospects in further sensing researches. [ABSTRACT FROM AUTHOR]

With the aggravation of sulfide pollution, more and more attention has been paid to the detection of sulfide in the environment. However, the detection of low-concentration sulfide is still a technical bottleneck to be solved urgently. In this study, a synergistic effect strategy that combines the co-catalysis of nanoporous gold (np-Au) and recombinant microbial cell with the excellent electrical conductivity of reduced graphene oxide (rGO) was proposed for the sensitive detection of low-concentration sulfide. A rGO/np-Au composite was fabricated and then used as an immobilization support for the bio-recognition element of recombinant Escherichia coli (E. coli) over-expressed sulfide: quinone oxidoreductase (SQR). A microbial biosensor (E. coli SQR/rGO/np-Au/GCE) was successfully constructed for the sensitive detection of low-concentration sulfide. Due to the synergistic effect of rGO, np-Au, and E. coli SQR cells, the sensitivity of the proposed microbial biosensor towards sulfide reached 400.42 μA mM−1 cm−2 with a wide linear response ranging from 100 nM to 7 mM, as well as a low detection limit of 98.5 nM using amperometric i-t curve method. Furthermore, the microbial biosensor was successfully applied to the detection of sulfide in wastewater with strong anti-interference ability, high reproducibility, and strong stability. These results confirmed that the proposed microbial biosensor was ideal for the detection of low-concentration sulfide in a reliable, specific, and sensitive way. • A sensitive microbial biosensor was successfully constructed for low-concentration sulfide detection. • The rGO/np-Au composite significantly improved the sensitivity of the microbial biosensor. • The reliable low-concentration sulfide detection in wastewater was successfully achieved. [ABSTRACT FROM AUTHOR]