Hydrothermal Reduction of Polyethylenimine and Polyethylene Glycol Dual-Functionalized Nanographene Oxide for High-Efficiency Gene Delivery

Liver Phosphoenolpyruvate Carboxykinase-1 Downregulation via siRNA-Functionalized Graphene Oxide Nanosheets Restores Glucose Homeostasis in a Type 2 Diabetes Mellitus In Vivo Model

Metabolic disorders have been increasing at an alarming rate, and one such example of metabolic disorder is type 2 diabetes mellitus (T2DM). Unregulated gluconeogenesis in T2DM results in increased hepatic glucose output that causes fasting and postprandial hyperglycaemia. Extensive proofs have shown that the downregulation of the key rate-limiting enzyme phosphoenolpyruvate carboxykinase-1 (PCK-1) of gluconeogenesis improved glucose homeostasis in vivo. In the present study, we have synthesized and characterized liver-specific stearic acid conjugated octaarginine (StA-R8) functionalized 4arm-2K-PEGamineylated graphene oxide nanosheets (GPR8) for the delivery of siRNA against PCK-1 in T2DM C57BL/6 mice. We found that a single intravenous administration of siRNA (3 mg/kg BW) conjugated to GPR8 (GPR8:PCK-1_{siRNA(3 mg/kg BW)} conjugate) in an optimized N/P ratio exploited as a therapeutic nanoformulation maintained glucose homeostasis for nearly 4 weeks in the T2DM mice. Efficient silencing of PCK-1 in T2DM liver tissue increased the phosphorylation of serine-256 of FOXO-1, thus showing a marked decrease in hepatic gluconeogenesis. Gluconeogenesis control and consequently glucose output from the liver furthermore partially enhanced liver and muscle insulin sensitivity results in the stimulation of the insulin/AKT-2 signaling pathway which indirectly restored glucose homeostasis in the treated T2DM group. Our therapeutic nanoformulation also improved glycogen storage in the liver and membrane translocation of GLUT4 in the muscle of the treated T2DM group. In conclusion, GPR8:PCK-1_{siRNA (3 mg/Kg BW)} restored glucose homeostasis by controlling the hepatic glucose production and improved peripheral insulin sensitivity as a consequence of reduced hyperglycemia. Thus, the current approach offered an alternative strategy for the therapeutics for T2DM.

Recent advances of two-dimensional materials in smart drug delivery nano-systems

Smart drug delivery nano-systems show significant changes in their physical or chemical properties in response to slight change in environmental physical and/or chemical signals, and further releasing drugs adjusted to the progression of the disease at the right target and rate intelligently. Two-dimensional materials possess dramatic status extend all over various scientific and technological disciplines by reason of their exceptional unique properties in application of smart drug delivery nano-systems. In this review, we summarized current progress to highlight various kinds of two-dimensional materials drug carriers which are widely explored in smart drug delivery systems as well as classification of stimuli responsive two-dimensional materials and the advantages and disadvantages of their applications. Consequently, we anticipate that this review might inspire the development of new two-dimensional materials with smart drug delivery systems, and deepen researchers' understanding of smart nano-carries based on two-dimensional materials.

Glycyrrhetinic acid-modified graphene oxide mediated siRNA delivery for enhanced liver-cancer targeting therapy

Graphene oxide (GO) has attracted huge attention in biomedical field in recent years. However, limited attempts have been invested in utilizing GO on active targeted delivery for gene therapy in liver cancer treatments. Glycyrrhetinic acid (GA) has been reported to be widely used as a targeting ligand to functionalize nanomaterials to treat hepatocellular carcinoma. In this article, GA is employed as a liver targeting ligand to construct GA, polyethylene glycol (PEG), polyamidoamine dendrimer (Dendrimer) and nano-graphene oxide (NGO) conjugate (GA-PEG-NGO-Dendrimer, GPND) for siRNA delivery for the first time. As we expected, GPND exhibited excellent stability, low toxicity, negligible hemolytic activity and remarkably high transfection efficiency in vitro. We also found effective VEGFa gene silencing in both mRNA and protein level in HepG2 cells. Notably, siRNA efficiently gathered in liver tumor tissues by the delivery of GPND, and eventually the growth of tumor tissues were inhibited with enhanced targeting capability and no obvious pathological changes. Moreover, histopathological results preliminarily support the high in vivo safety of GPND/anti-VEGFa siRNA nanocomplex. Collectively, GPND/siRNA nanocomplex, with high safety, targeting and transfection as well as prolonged half-life, is a promising nanomedicine and may provide a new direction for highly-specific targeted gene therapy.

Delivery of Oridonin and Methotrexate via PEGylated Graphene Oxide

Graphene oxide (GO) possessing plenty of hydroxyls and carboxyls is often used in the field of biomedicine. To improve its water solubility and biocompatibility, 6-armed poly(ethylene glycol) (PEG) was bonded on the surface of GO sheets via a facile amidation process to form the universal drug delivery platform (GO-PEG_10K-6arm) with a 200 nm size in favor of the enhanced permeability and retention effect. Herein, we prepared the stable and biocompatible platform of GO-PEG_10K-6arm under mild conditions and characterized the chemical structure and micromorphology via thermogravimetric analysis and atomic force microscopy. This nanosized GO-PEG_10K-6arm was found to be of very low toxicity to human normal cells of 293T and tumor cells of CAL27, MG63, and HepG2. Moreover, oridonin and methotrexate (MTX), widely used hydrophobic cancer chemotherapy drugs, were compounded with GO-PEG_10K-6arm via π-π stacking and hydrophobic interactions so as to afford nanocomplexes of oridonin@GO-PEG_10K-6arm and MTX@GO-PEG_10K-6arm, respectively. Both nanocomplexes could quickly enter into tumor cells, which was evidenced by inverted fluorescence microscopy using fluorescein isothiocyanate as a probe, and they both showed remarkably high cytotoxicity to the tumor cells of CAL27, MG63, and HepG2 within a broad range of concentration in comparison with free drugs. This kind of nanoscale drug delivery system based on GO-PEG_10K-6arm may have potential applications in biomedicine, and GO-PEG_10K-6arm would be a universal and available carrier for extensive hydrophobic anticarcinogens.

Aziridines and azetidines: building blocks for polyamines by anionic and cationic ring-opening polymerization

The synthesis of aziridine and azetidine monomers and their ring-opening polymerization via different mechanisms is reviewed.

Cellular Signaling Pathways Activated by Functional Graphene Nanomaterials

The paper reviews the network of cellular signaling pathways activated by Functional Graphene Nanomaterials (FGN) designed as a platform for multi-targeted therapy or scaffold in tissue engineering. Cells communicate with each other through a molecular device called signalosome. It is a transient co-cluster of signal transducers and transmembrane receptors activated following the binding of transmembrane receptors to extracellular signals. Signalosomes are thus efficient and sensitive signal-responding devices that amplify incoming signals and convert them into robust responses that can be relayed from the plasma membrane to the nucleus or other target sites within the cell. The review describes the state-of-the-art biomedical applications of FGN focusing the attention on the cell/FGN interactions and signalosome activation.

Advances on graphene-based nanomaterials for biomedical applications

Graphene-based nanomaterials, such as graphene oxide and reduced graphene oxide, have been attracting increasing attention in the field of biology and biomedicine over the past few years. Incorporation of these novel materials with drug, gene, photosensitizer and other cargos to construct novel delivery systems has witnessed rapid advance on the basis of their large surface area, distinct surface properties, excellent biocompatibility and pH sensitivity. Moreover, the inherent photothermal effect of these appealing materials enables them with the ability of killing targeting cells via a physical mechanism. Recently, more attentions have been attached to tissue engineering, including bone, neural, cardiac, cartilage, musculoskeletal, and skin/adipose tissue engineering, due to the outstanding mechanical strength, stiffness, electrical conductivity, various two-dimensional (2D) and three-dimensional (3D) morphologies of graphene-based nanomaterials. Herein, emerging applications of these nanomaterials in bio-imaging, drug/gene delivery, phototherapy, multimodality therapy and tissue engineering were comprehensively reviewed. Inevitably, the burgeon of this kind of novel materials leads to the endeavor to consider their safety so that this issue has been deeply discussed and summarized in our review. We hope that this review offers an overall understanding of these nanomaterials for later in-depth investigations.

Stable Dispersions of Covalently Tethered Polymer Improved Graphene Oxide Nanoconjugates as an Effective Vector for siRNA Delivery

Conjugates of poly(amidoamine) (PAMAM) with modified graphene oxide (GO) are attractive nonviral vectors for gene-based cancer therapeutics. GO protects siRNA from enzymatic cleavage and showed reasonable transfection efficiency along with simultaneous benefits of low cost and large scale production. PAMAM is highly effective in siRNA delivery but suffers from high toxicity with poor in vivo efficacy. Co-reaction of GO and PAMAM led to aggregation and more importantly, have detrimental effect on stability of dispersion at physiological pH preventing their exploration at clinical level. In the current work, we have designed, synthesized, characterized and explored a new type of hybrid vector (GPD), using GO synthesized via improved method which was covalently tethered with poly(ethylene glycol) (PEG) and PAMAM. The existence of covalent linkage, relative structural changes and properties of GPD is well supported by Fourier transform infrared (FTIR), UV-visible (UV-vis), Raman, X-ray photoelectron (XPS), elemental analysis, powder X-ray diffraction (XRD), thermogravimetry analysis (TGA), dynamic light scattering (DLS), and zeta potential. Scanning electron microscopy (SEM), and transmission electron microscopy (TEM) of GPD showed longitudinally aligned columnar self-assembled ∼10 nm thick polymeric nanoarchitectures onto the GO surface accounting to an average size reduction to ∼20 nm. GPD revealed an outstanding stability in both phosphate buffer saline (PBS) and serum containing cell medium. The binding efficiency of EPAC1 siRNA to GPD was supported by gel retardation assay, DLS, zeta potential and photoluminescence (PL) studies. A lower cytotoxicity with enhanced cellular uptake and homogeneous intracellular distribution of GPD/siRNA complex is confirmed by imaging studies. GPD exhibited a higher transfection efficiency with remarkable inhibition of cell migration and lower invasion than PAMAM and Lipofectamine 2000 suggesting its role in prevention of breast cancer progression and metastasis. A significant reduction in the expression of the specific protein against which siRNA was delivered is revealed by Western blot assay. Furthermore, a pH-triggered release of siRNA from the GPD/siRNA complex was studied to provide a mechanistic insight toward unloading of siRNA from the vector. Current strategy is a way forward for designing effective therapeutic vectors for gene-based antitumor therapy.

Optimizing the hybrid nanostructure of functionalized reduced graphene oxide/silver for highly efficient cancer nanotherapy

Conjugation of Herceptin to the surface of an optimized rGO-PLL/AgNP nanohybrid to achieve an efficient targeted DDS against Her2 positive breast cancer cells.

The treatment of femoral neck fracture using VEGF-loaded nanographene coated internal fixation screws

Purpose

Previous studies have proved that vascular endothelial growth factor (VEGF) has a dual role in the promotion of new bone formation and blood vessel repair during fracture healing. However, how to introduce VEGF to a fracture site safely and effectively is still a challenge. This study aimed to prepare a VEGF-loaded nanographene coated internal fixation screw and to evaluate its effects in the treatment of femoral neck fracture.

Methods

Nanographene coated screws were prepared by direct liquid-phase exfoliation of the graphite method, and the surface characteristics were observed through scanning electron microscopy (SEM). VEGF was loaded on nanographene coatings through physical adsorption, and the VEGF controlled release was examined by ELISA. Then a canine femoral neck fracture model was built to examine both the angiogenic and osteogenic properties of the VEGF-loaded coated screws. X-ray, micro-CT-based microangiography, and histopathologic evaluation were used to assess the fracture healing progress.

Results

The results demonstrated that nanographene could load VEGF effectively, and the accumulative release of VEGF clearly increased during the entire testing period (9 days) without burst release. In canine fracture models, the results of X-ray, microangiography, and histopathologic examination proved that the speed of fracture healing, new bone formation area, and revascularization of the fractured femoral heads in the VEGF-loaded coated screws groups were significantly higher than in the control groups.

Conclusion

Our study proved that VEGF-loaded nanographene coated screws were effective in the treatment of femoral neck fracture and prevention of avascular necrosis of femoral head.

Gene delivery ability of polyethylenimine and polyethylene glycol dual-functionalized nanographene oxide in 11 different cell lines

We recently developed a polyethylenimine (PEI) and polyethylene glycol (PEG) dual-functionalized reduced graphene oxide (GO) (PEG-nrGO-PEI, RGPP) for high-efficient gene delivery in HepG2 and Hela cell lines. To evaluate the feasibility and applicability of RGPP as a gene delivery carrier, we here assessed the transfection efficiency of RGPP on gene plasmids and siRNA in 11 different cell lines. Commercial polyalkyleneimine cation transfection reagent (TR) was used as comparison. In HepG2 cells, RGPP exhibited much stronger delivery ability for siRNA and large size plasmids than TR. For green fluorescent protein (GFP) plasmid, RGPP showed about 47.1% of transfection efficiency in primary rabbit articular chondrocytes, and about 27% of transfection efficiency in both SH-SY5Y and A549 cell lines. RGPP exhibited about 37.2% of GFP plasmid transfection efficiency in EMT6 cells and about 26.0% of GFP plasmid transfection efficiency in LO2 cells, but induced about 33% of cytotoxicity in both cell lines. In 4T1 and H9C2 cell lines, RGPP had less than 10% of GFP plasmid transfection efficiency. Collectively, RGPP is a potential nano-carrier for high-efficiency gene delivery, and needs to be further optimized for different cell lines.