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An interlayer nanocomposite (CC@rGO) consisting of a graphene heterojunction with CoO and Co9S8 was prepared using a simple and low-cost hydrothermal calcination method, which was tested as a cathode sulfur carrier for lithium-sulfur batteries. The CC@rGO composite comprises a spherical heterostructure uniformly distributed between graphene sheet layers, preventing stacking the graphene sheet layer. After the introduction of cobalt heterojunction on a graphene substrate, the Co element content increases the reactive sites of the composite and improves its electrochemical properties to some extent. The composite exhibited good cycling performance with an initial discharge capacity of 847.51 mAh/g at 0.5 C and a capacity decay rate of 0.0448% after 500 cycles, which also kept 452.91 mAh/g at 1 C and in the rate test from 3 C back to 0.1 C maintained 993.27 mAh/g. This article provides insight into the design of cathode materials for lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Ion sieving is of great importance in a variety of applications, such as water desalination/purification, biomedical engineering and so on. The currently available techniques, based on ion size sieving by constructing membranes with nanochannels and nanopores, are still not able to achieve precise sieving of mono-/multi-valent metal ions. Here, we report on the fabrication of graphene-based membranes by constructing uniform two-dimensional (2D) nanochannels with effective channel heights of ~ 8 Å for precise and efficient sieving of mono-/multi-valent metal ions. Our membranes with uniform 2D nanochannels are built using facilely reduced graphene oxide (FRGO) nanosheets, which are controllably fabricated by avoiding the corrugation of graphene oxide (GO) nanosheets and controlling the content of oxidation groups during the reduction process. We illustrate the ability of precise sieving of mono-/multi-valent metal ions afforded by this technique by fabricating FRGO membranes with uniform 2D nanochannels, and demonstrate the excellent repeatability and long-term stability of FRGO membranes for sieving of mono-/multi-valent metal ions. [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]

Carbon nanotubes and graphene are both low-dimensional sp2 carbon nanomaterials exhibiting many unique physical and chemical properties that are interesting in a wide range of areas including nanomedicine. Since 2004, carbon nanotubes have been extensively explored as drug delivery carriers for the intracellular transport of chemotherapy drugs, proteins, and genes. In vivo cancer treatment with carbon nanotubes has been demonstrated in animal experiments by several different groups. Recently, graphene, another allotrope of carbon, has also shown promise in various biomedical applications. In this article, we will highlight recent research on these two categories of closely related carbon nanomaterials for applications in drug delivery and cancer therapy, and discuss the opportunities and challenges in this rapidly growing field. [ABSTRACT FROM AUTHOR]

Nano-graphene as a class of two-dimensional sp 2 carbon nanomaterial has attracted tremendous attentions in various fields in the past decade. Utilizing its unique physical and chemical properties, nano-graphene has also shown great promises in the area of biomedicine, for application in biosensing, imaging and therapy. In particular, with all atoms exposed on its surface, nano-graphene exhibits ultra-high surface area available for efficient binding/loading of various biomolecules of interests, and has been widely used as multifunctional nano-carriers for drug and gene delivery. In this review article, we will summarize the recent advances in the development of nano-graphene as stimuli-responsive nano-carriers for drug delivery, as well as the applications of these smart systems for cancer therapy. [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]

[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]

Graphene has a wide range of applications in anti-corrosion coatings due to its excellent barrier, shielding, and mechanical properties. However, traditional graphene synthesis methods, including the production of graphene oxide (GO) using Homer's method and then its reduction in the form of reduced graphene oxide (rGO) are time-consuming, energy-consuming, and environmentally polluting, which limits their application in anti-corrosion coatings. This study leveraged the capabilities of flash Joule heating (FJH) to synthesize flash coal-based graphene (FCBG) from Taixi anthracite (TA) within 200 ms without pretreatments or chemical reagents. The FJH had the advantages of low energy consumption and being environmentally friendly. Compared with the rGO, the FCBG prepared by FJH was characterized by fewer defects, larger carbon sheets, and a turbostratic structure. Moreover, carbon steel Q235 was used as the substrate to prepare anti-corrosion coatings by mixing FCBG at different flash voltages with epoxy resin (EP). Based on this, the electrochemical performance of different coatings was compared before and after salt spray corrosion. The results demonstrated that the FCBG composite anti-corrosion coating (EP/FCBG 190) prepared using EP and FCBG synthesized at 190 V in the FJH, displayed stronger corrosion resistance than the EP and rGO composite coating (EP/rGO). The FJH synthesis process provides a feasible route for improving the synthesis process of the anti-corrosion coatings and the high value-added utilization of coal. [Display omitted] • The flash Joule heating can heat the samples in situ. • It only takes 200 ms to synthesize flash coal-based graphene. • No pretreatment and chemicals required. • FCBG 190 has better corrosion resistance than rGO. [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]

Abstract: In recent years, graphene and graphene-based nanocomposites owning to their highly enriched physical and chemical properties have been widely explored for applications in many different fields including biomedicine. In the present work, we decorate graphene oxide (GO) by both iron oxide nanoparticles (IONPs) and gold, forming a multi-functional magnetic & plasmonic GO–IONP–Au nanocomposite with strong superparamagnetism and significantly enhanced optical absorbance in the near-infrared (NIR) region. We then coat the nanocomposite with polyethylene glycol (PEG), obtaining GO–IONP–Au–PEG with high stability in physiological environments and no significant in vitro toxicity. Remarkably enhanced photothermal cancer ablation effect using GO–IONP–Au–PEG is realized in comparison to PEGylated GO used in our earlier studies, as demonstrated in both in vitro cell tests and in vivo animal experiments. Moreover, the IONP and Au compartments in the GO–IONP–Au–PEG nanocomposite could be further taken advantages for magnetic resonance (MR) and X-ray dual-modal imaging. Our work shows the promise of using graphene-based multi-functional nanocomposite as cancer theranostics. [Copyright &y& Elsevier]

Abstract: Graphene-based nanomaterials have attracted tremendous attention in the field of biomedicine due to their intriguing properties. Herein, we report tumor vasculature targeting and imaging in living mice using reduced graphene oxide (RGO), which was conjugated to the anti-CD105 antibody TRC105. The RGO conjugate, 64Cu–NOTA–RGO–TRC105, exhibited excellent stability in vitro and in vivo. Serial positron emission tomography (PET) imaging studies non-invasively assessed the pharmacokinetics and demonstrated specific targeting of 64Cu–NOTA–RGO–TRC105 to 4T1 murine breast tumors in vivo, compared to non-targeted RGO conjugate (64Cu–NOTA–RGO). In vivo (e.g., blocking 4T1 tumor uptake with excess TRC105), in vitro (e.g., flow cytometry), and ex vivo (e.g., histology) experiments confirmed the specificity of 64Cu–NOTA–RGO–TRC105 for tumor vascular CD105. Since RGO exhibits desirable properties for photothermal therapy, the tumor-specific RGO conjugate developed in this work may serve as a promising theranostic agent that integrates imaging and therapeutic components. [Copyright &y& Elsevier]

Abstract: Graphene oxide (GO) and its functionalized derivatives have attracted great attention in biomedicine in recent years. A number of groups including ours have studied the in vivo behaviors of functionalized nano-graphene after intravenous injection or inhalation, and uncovered the surface coating & size dependent biodistribution and toxicology profiles for this type of nanomaterials. However, the fate of GO derivatives in animals after oral feeding and intraperitoneal (i.p.) injection, which are two other major drug administration routes, remain unclear. Therefore, in this work, we sought to systematically investigate in vivo biodistribution and potential toxicity of as-made GO and a number of polyethylene glycol (PEG) functionalized GO derivatives with different sizes and surface coatings, after oral and intraperitoneal administration at high doses. It is found that 125I labeled PEGylated GO derivatives show no obvious tissue uptake via oral administration, indicating the rather limited intestinal adsorption of those nanomaterials. In contrast, high accumulation of PEGyalted GO derivatives, but not as-made GO, in the reticuloendothelial (RES) system including liver and spleen is observed after i.p. injection. Further investigations based on histological examination of organ slices and hematological analysis discover that although GO and PEGylated GO derivatives would retain in the mouse body over a long period of time after i.p. injection, their toxicity to the treated animals is insignificant. Our work is an important fundamental study that offers a deeper understanding of in vivo behaviors and toxicology of functionalized nano-graphene in animals, depending on their different administration routes. [Copyright &y& Elsevier]

Abstract: Photothermal therapy as a physical treatment approach to destruct cancer has emerged as an alternative of currently used cancer therapies. Previously we have shown that polyethylene glycol (PEG) functionalized nano-graphene oxide (nGO-PEG) with strong optical absorption in the near-infrared (NIR) region was a powerful photothermal agent for in vivo cancer treatment. In this work, by using ultra-small reduced graphene oxide (nRGO) with non-covalent PEG coating, we study how sizes and surface chemistry affect the in vivo behaviors of graphene, and remarkably improve the performance of graphene-based in vivo photothermal cancer treatment. Owing to the enhanced NIR absorbance and highly efficient tumor passive targeting of nRGO-PEG, excellent in vivo treatment efficacy with 100% of tumor elimination is observed after intravenous injection of nRGO-PEG and the followed 808 nm laser irradiation, the power density (0.15 W/cm2, 5 min) of which is an order of magnitude lower than that usually applied for in vivo tumor ablation using many other nanomaterials. All mice after treatment survive over a period of 100 days without a single death or any obvious sign of side effect. Our results highlight that both surface chemistry and sizes are critical to the in vivo performance of graphene, and show the promise of using optimized nano-graphene for ultra-effective photothermal treatment, which may potentially be combined with other therapeutic approaches to assist our fight against cancer. [Copyright &y& Elsevier]

Abstract: Development of biocompatible surface coating is critical to engineer various functional nanomaterials for biomedical applications. Here, we present a new surface chemistry of graphene by covalently conjugating graphene oxide (GO) with dextran (DEX), a biocompatible polymer widely used for surface coating of biomaterials. Compared with GO, the graphene–dextran (GO–DEX) conjugate shows reduced sheet sizes, increased thickness and significantly improved stability in physiological solutions. Cellular experiments uncover that DEX coating on GO offers remarkably reduced cell toxicity. We further label GO–DEX with a radioactive isotope, 125I, for in vivo tracking in animal studies. It is found that GO–DEX accumulates in the reticuloendothelial system (RES) including liver and spleen after intravenous injection, and importantly, shows obvious clearance from the mouse body within a week without causing noticeable short-term toxicity to the treated animals. Our results suggest that this DEX coating method on GO may potentially be useful to the further development of novel graphene-based bioconjugates for various biomedical applications. [Copyright &y& Elsevier]