JI017 Induces Cell Autophagy and Apoptosis via Elevated Levels of Reactive Oxygen Species in Human Lung Cancer Cells.

Lung cancer is one of the most common malignant tumors and a leading cause of cancer-related death in the worldwide. Various anticancer drugs, such as cisplatin and pemetrexed, have been developed for lung cancer treatment but due their drug resistance and side effects, novel treatments need to be developed. In this study, the efficacy of the natural drug JI017, which is known to have few side effects, was tested in lung cancer cells. JI017 inhibited A549, H460, and H1299 cell proliferation. JI017 induced apoptosis, regulated apoptotic molecules, and inhibited colony formation. Additionally, JI017 increased intracellular ROS generation. JI017 downregulated PI3K, AKT, and mTOR expression. JI017 increased the cytosolic accumulation of LC3. We found that JI017 promoted apoptosis through ROS-induced autophagy. Additionally, the xenograft tumor size was smaller in JI017-treated mice. We found that JI017 treatment increased MDA concentrations, decreased Ki-67 protein levels, and increased cleaved caspase-3 and LC3 levels in vivo. JI017 decreased cell proliferation and increased apoptosis by inducing autophagy signaling in H460 and H1299 lung cancer cells. Targeting JI017 and autophagy signaling could be useful in lung cancer treatment.

Functional Graphene Nanomaterials-Based Hybrid Scaffolds for Osteogenesis and Chondrogenesis.

With the emerging trends and recent advances in nanotechnology, it has become increasingly possible to overcome current hurdles for bone and cartilage regeneration. Among the wide type of nanomaterials, graphene (G) and its derivatives (graphene-based materials, GBMs) have been highlighted due to the specific physicochemical and biological properties. In this review, we present the recent development of GBM-based scaffolds for bone and cartilage engineering, focusing on the formulation/shape/size-dependent characteristics, types of scaffold and modification, biocompatibility, bioactivity and underlying mechanism, drawback and prospect of each study. From the findings described herein, mechanical property, biocompatibility, osteogenic and chondrogenic property of GBM-based scaffolds could be significantly enhanced through various scaffold fabrication methods and conjugation with polymers/nanomaterials/drugs. In conclusion, the results presented in this review support the promising prospect of using GBM-based scaffolds for improved bone and cartilage tissue engineering. Although GBM-based scaffolds have some limitations to be overcome by future research, we expect further developments to provide innovative results and improve their clinical potential for bone and cartilage regeneration.

Reduced HIF-1α Stability Induced by 6-Gingerol Inhibits Lung Cancer Growth through the Induction of Cell Death.

Lung cancer (LC) is the leading global cause of cancer-related death, and metastasis is a great challenge in LC therapy. Additionally, solid cancer, including lung, prostate, and colon cancer, are characterized by hypoxia. A low-oxygen state is facilitated by the oncogene pathway, which correlates with a poor cancer prognosis. Thus, we need to understand the related mechanisms in solid tumors to improve and develop new anticancer strategies. The experiments herein describe an anticancer mechanism in which heat shock protein 90 (HSP90) stabilizes HIF-1α, a master transcription factor of oxygen homeostasis that has been implicated in the survival, proliferation and malignant progression of cancers. We demonstrate the efficacy of 6-gingerol and the molecular mechanism by which 6-gingerol inhibits LC metastasis in different oxygen environments. Our results showed that cell proliferation was inhibited after 6-gingerol treatment. Additionally, HIF-1α, a transcriptional regulator, was found to be recruited to the hypoxia response element (HRE) of target genes to induce the transcription of a series of target genes, including MMP-9, vimentin and snail. Interestingly, we found that 6-gingerol treatment suppressed activation of the transcription factor HIF-1α by downregulating HSP90 under both normoxic and hypoxic conditions. Furthermore, an experiment in an in vivo xenograft model revealed decreased tumor growth after 6-gingerol treatment. Both in vitro and in vivo analyses showed the inhibition of metastasis through HIF-1α/HSP90 after 6-gingerol treatment. In summary, our study demonstrates that 6-gingerol suppresses proliferation and blocks the nuclear translocation of HIF-1α and activation of the EMT pathway. These data suggest that 6-gingerol is a candidate antimetastatic treatment for LC.

Contact Engineering High-Performance n-Type MoTe2 Transistors.

Semiconducting MoTe2 is one of the few two-dimensional (2D) materials with a moderate band gap, similar to silicon. However, this material remains underexplored for 2D electronics due to ambient instability and predominantly p-type Fermi level pinning at contacts. Here, we demonstrate unipolar n-type MoTe2 transistors with the highest performance to date, including high saturation current (>400 µA/µm at 80 K and >200 µA/µm at 300 K) and relatively low contact resistance (1.2 to 2 kΩ·µm from 80 to 300 K), achieved with Ag contacts and AlOx encapsulation. We also investigate other contact metals (Sc, Ti, Cr, Au, Ni, Pt), extracting their Schottky barrier heights using an analytic subthreshold model. High-resolution X-ray photoelectron spectroscopy reveals that interfacial metal-Te compounds dominate the contact resistance. Among the metals studied, Sc has the lowest work function but is the most reactive, which we counter by inserting monolayer hexagonal boron nitride between MoTe2 and Sc. These metal-insulator-semiconductor (MIS) contacts partly depin the metal Fermi level and lead to the smallest Schottky barrier for electron injection. Overall, this work improves our understanding of n-type contacts to 2D materials, an important advance for low-power electronics.

Graphene-Functionalized Biomimetic Scaffolds for Tissue Regeneration.

Graphene is a two-dimensional atomic layer of graphite, where carbon atoms are assembled in a honeycombed lattice structure. Recently, graphene family nanomaterials, including pristine graphene, graphene oxide and reduced graphene oxide, have increasingly attracted a great deal of interest from researchers in a variety of science, engineering and industrial fields because of their unique structural and functional features. In particular, extensive studies have been actively conducted in the biomedical and related fields, including multidisciplinary and emerging areas, as their stimulating effects on cell behaviors have been becoming an increasing concern. Herein, we are attempting to summarize some of recent findings in the fields of tissue regeneration concerning the graphene family nanomaterial-functionalized biomimetic scaffolds, and to provide the promising perspectives for the possible applications of graphene family nanomaterial.

Graphene-Based Nanocomposites as Promising Options for Hard Tissue Regeneration.

Tissues are often damaged by physical trauma, infection or tumors. A slight injury heals naturally through the normal healing process, while severe injury causes serious health implications. Therefore, many efforts have been devoted to treat and repair various tissue defects. Recently, tissue engineering approaches have attracted a rapidly growing interest in biomedical fields to promote and enhance healing and regeneration of large-scale tissue defects. On the other hand, with the recent advances in nanoscience and nanotechnology, various nanomaterials have been suggested as novel biomaterials. Graphene, a two-dimensional atomic layer of graphite, and its derivatives have recently been found to possess promoting effects on various types of cells. In addition, their unique properties, such as outstanding mechanical and biological properties, allow them to be a promising option for hard tissue regeneration. Herein, we summarized recent research advances in graphene-based nanocomposites for hard tissue regeneration, and highlighted their promising potentials in biomedical and tissue engineering.

The prevention of 2,4-dinitrochlorobenzene-induced inflammation in atopic dermatitis-like skin lesions in BALB/c mice by Jawoongo.

BACKGROUND: Jawoongo is an herbal mixture used in traditional medicine to treat skin diseases. This study aimed to investigate whether Jawoongo ameliorates Atopic dermatitis (AD)-like pathology in mice and to understand its underlying cellular mechanisms. METHODS: AD was induced by 2, 4-Dinitrocholrlbenzene (DNCB) in BALB/c mice. Treatment with Jawoongo was assessed to study the effect of Jawoongo on AD in mice. Histological Analysis, blood analysis, RT-PCR, western blot analysis, ELISA assay and cell viability assay were performed to verify the inhibitory effect of Jawoongo on AD in mice. RESULTS: We found that application of Jawoongo in an ointment form on AD-like skin lesions on DNCB-exposed BALB/c mice reduced skin thickness and ameliorated skin infiltration with inflammatory cells, mast cells and CD4+ cells. The ointment also reduced the mRNA levels of IL-2, IL-4, IL-13 and TNF-α in the sensitized skin. Leukocyte counts and the levels of IgE, IL-6, IL-10 and IL-12 were decreased in the blood of the DNCB-treated mice. Furthermore, studies on cultured cells demonstrated that Jawoongo exhibits anti-inflammatory activities, including the suppression of proinflammatory cytokine expression, nitric oxide (NO) production, and inflammation-associated molecule levels in numerous types of agonist-stimulated innate immune cell, including human mast cells (HMC-1), murine macrophage RAW264.7 cells, and splenocytes isolated from mice. CONCLUSION: These findings indicate that Jawoongo alleviates DNCB-induced AD-like symptoms via the modulation of several inflammatory responses, indicating that Jawoongo might be a useful drug for the treatment of AD.

Effects of Angelicae dahuricae Radix on 2, 4-Dinitrochlorobenzene-Induced Atopic Dermatitis-Like Skin Lesions in mice model.

BACKGROUND: Atopic dermatitis (AD) is an inflammatory, chronically relapsing, and intensively pruritic skin disease that affect 10-30% of the global population. Angelicae dahuricae Radix (ADR) has been reported to be anti-inflammatory in Korean Medicine. In the present study, we investigated whether ADR suppresses the progression of AD in animal model. METHODS: AD was induced by 2, 4-Dinitrochlorobenzene (DNCB). ADR was orally administered to mice to study the effect of ADR on AD. Histological Analysis, immunohistochemistry, blood analysis, RT-PCR, and ELISA assay were performed. RESULTS: ADR significantly suppressed AD-like symptoms in BALB/c mice: ADR decreased skin thickness and spleen weight of mice. ADR reduced infiltration of mast cells, inflammatory cells and CD4+ cells into mouse skin. ADR lowered the number of WBCs in the blood of mice. ADR reduced the levels of IgE, IL-6, IL-10 and IL-12 in mice serum. ADR down-regulated mRNA expression of IL-4, IL-6 and TNF-α in mouse skin tissue. CONCLUSION: Our present study clearly indicates that ADR suppresses the progression of AD induced by DNCB in BALB/c mice. This suggests that ADR might be a useful drug for the treatment of AD.

Tonggyu-tang, a traditional Korean medicine, suppresses pro-inflammatory cytokine production through inhibition of MAPK and NF-κB activation in human mast cells and keratinocytes.

BACKGROUND: Allergic diseases including allergic rhinitis, asthma, and atopic dermatitis are increasing worldwide. Common medications used to treat these inflammatory disorders are anti-histamines and corticosteroids, but they have their own limitations such as short duration and severe side effects. Thus, interest in complementary and alternative medicine is continually growing. Here, we investigate the anti-inflammatory mechanisms of Tonggyu-tang (TGT), a traditional Korean medicine that has been used to treat patients with allergic nasal disorders. METHODS: We measured mRNA expressions and production of pro-inflammatory cytokines such as interleukin (IL)-4, IL-6, IL-8 and tumor necrosis factor alpha (TNF-α) by RT-PCR and ELISA assays in HMC-1 (human mast cell line-1) and HaCaT cells, immortalized human keratinocytes. Moreover, we evaluated the effect of TGT on two major inflammation-related pathways, mitogen activated protein kinase (MAPK) and NF-κB signaling pathway in these two cells. RESULTS: Our results revealed that that TGT significantly reduced the expression and production of inflammatory cytokines such as IL-4, IL-6, IL-8, and TNF-α in the agonist-treated HMC-1 and HaCaT cells. We also found that TGT suppressed MAPK signaling pathway including extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38), and c-Jun N-terminal kinase (JNK) as well as NF-κB pathway, which are known to regulate inflammatory cytokine expression. CONCLUSION: Taken together, our results demonstrate that TGT inhibits expression of pro-inflammatory cytokines by suppressing MAPK and NF-kB pathway in both mast cells and keratinocytes, suggesting the potential use of TGT in treating allergic inflammatory diseases.

The Effect of Reduced Graphene Oxide-Coated Biphasic Calcium Phosphate Bone Graft Material on Osteogenesis.

This study was conducted to evaluate the effect of biphasic calcium phosphate (BCP) coated with reduced graphene oxide (rGO) as bone graft materials on bone regeneration. The rGO-coated BCP bone graft material was fabricatied by mixing rGO and BCP at various concentrations. The surface charge of rGO-coated BCP was measured to be -14.43 mV, which formed a static electrostatic interaction. Cell viabilities were significantly diminished at higher concentrations of ≥100 µg/mL. The calvarial defects of 48 rats were implanted rGO-coated BCPs at a weight ratio of 2:1000 (rGO2), 4:1000 (rGO4), and 10:1000 (rGO10), repectively. BCP was used as a control group. The micro-CT and histological analysis were performed to evaluate new bone formation at 2 and 8 weeks after surgery. The results showed that the new bone volume (mm³) was significantly higher in the experimental groups than in the control group. Histological analysis showed that new bone areas (%) were significantly higher in the rGO2 and rGO10 than in the control, and significantly higher in rGO4 than in the rGO2 and rGO10. Conclusively, the rGO-coated BCP was found to be effective on osteogenesis and the concentration of the composite was an important factor.

Rhus verniciflua Stokes (RVS) and butein induce apoptosis of paclitaxel-resistant SKOV-3/PAX ovarian cancer cells through inhibition of AKT phosphorylation.

BACKGROUND: Rhus verniciflua Stokes (RVS) belongs to the Anacardiaceae family and traditionally used for cancer treatment. RVS and butein, a major compound of RVS, were known to induce apoptosis via AKT inhibition in cancer cells. Thus, in this study, we investigated the effect of RVS and its derivative compounds (fisetin, quercetin, butein) on cell death in SKOV-3/PAX cells. METHODS: The 80 % ethanol extract of RVS and its derivative compounds (fisetin, quercetin, butein) were prepared. The cytotoxicity was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Apoptotic cells were detected by staining with propidium iodide (PI) and Annexin V-fluorescein isothiocyanate/7-aminoactinomycin D (Annexin V-FITC/7-AAD). The expression level of intracellular signaling related-proteins in apoptosis and growth were measured by western blot assay. RESULTS: We found that RVS and butein suppressed the growth of SKOV-3/PAX cells in a dose-dependent manner. We also found that RVS and butein produced the cleavage of caspase-9, -8, -3, and PARP. Similarly, sub-G1 phase and Annexin V-FITC positive cells were increased by RVS and butein. Moreover, RVS and butein significantly reduced AKT phosphorylation in SKOV-3/PAX cells. PI3K inhibitor LY294002 caused PARP cleavage supporting our finding. CONCLUSION: Our data clearly indicate that RVS and butein induce apoptosis of SKOV-3/PAX cells through inhibition of AKT activation. RVS and butein could be useful compounds for the treatment for paclitaxel resistant-ovarian cancer.

Smoking cessation programmes using traditional medicine in Korea.

BACKGROUND: There are growing interests in using various methods including traditional and complementary medicines (T&CM) for tobacco control. The study aimed to introduce how traditional Korean medicine (TKM) applied to smoking cessation programmes in Korea and to show the detail information of each programme for designing other smoke cessation programmes. METHODS: Reports of the smoke cessation programmes in Korea were searched on March 10th, 2016, from the webpages of the related agencies and the databases: the Ministry of Health and Welfare, the Korea Health Foundation, the Association of Korean Medicine, PubMed, Google scholar, the RISS, the KISS, the NDSL, and the OASIS. Smoking cessation programmes, projects, or services using traditional Korean medicine (TKM) were included with no language, implementation site, and year restrictions. RESULTS: The three smoking cessation programmes using TKM in South Korea were the public health centre smoking cessation programme (PHC-SCP), the Ministry of Gender Equality & Family smoking cessation programme (MOGEF-SCP), and the National Health Insurance Service smoking cessation treatment project (NHIS-SCP). All programmes included ear acupuncture and counselling. Manual acupuncture was only used in the NHIS-SCP. The MOGEF-SCP and the NHIS-SCP used herbal medicines selectively. The PHC-SCP and MOGEF-SCP provided education programme and other tools such as non-smoking doll, self-writing handbook. They were run at no cost for participants. Treatment period were different for each programmes, 3 weeks, 4 weeks, 8 to 12 weeks, respectively. Treatment frequency was twice a week for PHC-SCP and MOGEF-SCP, and dependent on each clinic for NHIS-SCP. CONCLUSIONS: This study showed the summaries of the smoking cessation programme that used TKM. The three programmes and the detail information will be a reference for other countries that are going to apply T&CM to their smoking cessation programme. Though TKM integrated smoking cessation programmes had been contributed to stop smoking, persistent efforts are needed to develop more effective and various treatments. In addition, this study suggests that consistent support and systematic reporting system are needed to be successful in non-smoking strategy.

Anti-allergic effects of So-Cheong-Ryong-Tang in ovalbumin-induced allergic rhinitis model.

Allergic rhinitis (AR) is an allergic inflammation of the nasal airways. The Korean herbal medicine, So-Cheong-Ryong-Tang (SCRT) has been typically used for the treatment of AR for hundreds of years. In the present study, we investigated whether SCRT suppresses the progression of AR in animal model. AR was induced by ovalbumin (OVA). Treatment with SCRT was assessed to study the effect of SCRT on AR in mice. Histological analysis, multiplex cytokine assay, blood analysis, cell viability assay, RT-PCR and Elisa assay were performed to verify inhibitory effect of SCRT on AR. SCRT reduced infiltration of inflammatory cells into nasal cavity. SCRT reduced infiltration of mast cells into nasal mucosa. SCRT reduced the levels of cytokines (IL-4 and LIF) in the serum. SCRT reduced the levels of leukocytes in the blood. SCRT decreased cell viability of HMC-1 cells and splenocyte. SCRT suppressed IL-4 level in HMC-1 cells and splenocyte cells in a dose-dependent manner. SCRT suppressed IL-6 level and TNF-α level in splenocyte. SCRT suppresses the progression of AR induced by OVA. SCRT might be a useful drug for the treatment of AR.

Graphene-Based Thermopile for Thermal Imaging Applications.

In this work, we leverage graphene's unique tunable Seebeck coefficient for the demonstration of a graphene-based thermal imaging system. By integrating graphene based photothermo-electric detectors with micromachined silicon nitride membranes, we are able to achieve room temperature responsivities on the order of ~7-9 V/W (at λ = 10.6 µm), with a time constant of ~23 ms. The large responsivities, due to the combination of thermal isolation and broadband infrared absorption from the underlying SiN membrane, have enabled detection as well as stand-off imaging of an incoherent blackbody target (300-500 K). By comparing the fundamental achievable performance of these graphene-based thermopiles with standard thermocouple materials, we extrapolate that graphene's high carrier mobility can enable improved performances with respect to two main figures of merit for infrared detectors: detectivity (>8 × 10(8) cm Hz(1/2) W(-1)) and noise equivalent temperature difference (<100 mK). Furthermore, even average graphene carrier mobility (<1000 cm(2) V(-1) s(-1)) is still sufficient to detect the emitted thermal radiation from a human target.

Cucurbitacin D induces cell cycle arrest and apoptosis by inhibiting STAT3 and NF-κB signaling in doxorubicin-resistant human breast carcinoma (MCF7/ADR) cells.

Breast cancer is the most common cancer for women and is a major cause of mortality in women. Doxorubicin is a generally used chemotherapy drug for breast cancer. However, multidrug resistance of breast cancer interferes with the chemotherapy. We examined whether cucurbitacin D affects doxorubicin resistance of MCF7/ADR breast cancer cells. Cell viability was measured by MTT assay. Levels of p-STAT3, p-NF-κB, IκB, and caspases were measured by Western blot analysis. Nuclear staining of Stat3 and NF-κB was measured by immunocytochemistry. STAT3 and NF-κB transcriptional activity was detected by STAT3 and NF-κB luciferase reporter gene assays. Analysis of cell cycle arrest was performed by flow cytometry. Induction of apoptosis by cucurbitacin D was measured by Annexin V-FITC/propidium iodide assay. More than 90% of MCF7/ADR cells lived upon treatment with doxorubicin for 24 h. However, upon treatment with cucurbitacin D, cell death was more than 60%. Co-administration of cucurbitacin D and doxorubicin induced apoptosis, and G2/M cell cycle arrest, and inhibited upregulated Stat3 by doxorubicin on MCF7/ADR cells. Additionally, cucurbitacin D led to an increase in the IκBα level in the cytosol and a decrease in the p-NF-κB level in the nucleus. Finally, cucurbitacin D inhibited translocation of Stat3 and NF-κB and decreased transcriptional activity in the nucleus. Cucurbitacin D decreases cell proliferation and induces apoptosis by inhibiting Stat3 and NF-κB signaling in doxorubicin-resistant breast cancer cells. Cucurbitacin D could be used as a useful compound to treat adriamycin-resistant patients.

Stimulated myoblast differentiation on graphene oxide-impregnated PLGA-collagen hybrid fibre matrices.

BACKGROUND: Electrospinning is a simple and effective method for fabricating micro- and nanofiber matrices. Electrospun fibre matrices have numerous advantages for use as tissue engineering scaffolds, such as high surface area-to-volume ratio, mass production capability and structural similarity to the natural extracellular matrix (ECM). Therefore, electrospun matrices, which are composed of biocompatible polymers and various biomaterials, have been developed as biomimetic scaffolds for the tissue engineering applications. In particular, graphene oxide (GO) has recently been considered as a novel biomaterial for skeletal muscle regeneration because it can promote the growth and differentiation of myoblasts. Therefore, the aim of the present study was to fabricate the hybrid fibre matrices that stimulate myoblasts differentiation for skeletal muscle regeneration. RESULTS: Hybrid fibre matrices composed of poly(lactic-co-glycolic acid, PLGA) and collagen (Col) impregnated with GO (GO-PLGA-Col) were successfully fabricated using an electrospinning process. Our results indicated that the GO-PLGA-Col hybrid matrices were comprised of randomly-oriented continuous fibres with a three-dimensional non-woven porous structure. Compositional analysis showed that GO was dispersed uniformly throughout the GO-PLGA-Col matrices. In addition, the hydrophilicity of the fabricated matrices was significantly increased by blending with a small amount of Col and GO. The attachment and proliferation of the C2C12 skeletal myoblasts were significantly enhanced on the GO-PLGA-Col hybrid matrices. Furthermore, the GO-PLGA-Col matrices stimulated the myogenic differentiation of C2C12 skeletal myoblasts, which was enhanced further under the culture conditions of the differentiation media. CONCLUSIONS: Taking our findings into consideration, it is suggested that the GO-PLGA-Col hybrid fibre matrices can be exploited as potential biomimetic scaffolds for skeletal tissue engineering and regeneration because these GO-impregnated hybrid matrices have potent effects on the induction of spontaneous myogenesis and exhibit superior bioactivity and biocompatibility.

Cell-Adhesive Matrices Composed of RGD Peptide-Displaying M13 Bacteriophage/Poly(lactic-co-glycolic acid) Nanofibers Beneficial to Myoblast Differentiation.

Recently, there has been considerable effort to develop suitable scaffolds for tissue engineering applications. Cell adhesion is a prerequisite for cells to survive. In nature, the extracellular matrix (ECM) plays this role. Therefore, an ideal scaffold should be structurally similar to the natural ECM and have biocompatibility and biodegradability. In addition, the scaffold should have biofunctionality, which provides the potent ability to enhance the cellular behaviors, such as adhesion, proliferation and differentiation. This study concentrates on fabricating cell-adhesive matrices composed of RGD peptide-displaying M13 bacteriophage (RGD-M13 phage) and poly(lactic-co-glycolic acid, PLGA) nanofibers. Long rod-shaped M13 bacteriophages are non-toxic and can express many desired proteins on their surface. A genetically engineered M13 phage was constructed to display RGD peptides on its surface. PLGA is a biodegradable polymer with excellent biocompatibility and suitable physicochemical property for adhesive matrices. In this study, RGD-M13 phage/PLGA hybrid nanofiber matrices were fabricated by electrospinning. The physicochemical properties of these matrices were characterized by scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and contact angle measurement. In addition, the cellular behaviors, such as the initial attachment, proliferation and differentiation, were analyzed by a CCK-8 assay and immunofluorescence staining to evaluate the potential application of these matrices to tissue engineering scaffolds. The RGD-M13 phage/PLGA nanofiber matrices could enhance the cellular behaviors and promote the differentiation of C2C12 myoblasts. These results suggest that the RGD-M13 phage/PLGA nanofiber matrices are beneficial to myoblast differentiation and can serve as effective tissue engineering scaffolds.

Stimulated Osteogenic Differentiation of Human Mesenchymal Stem Cells by Reduced Graphene Oxide.

Osteoprogenitor cells play a significant role in the growth or repair of bones, and have great potential as cell sources for regenerative medicine and bone tissue engineering, but control of their specific differentiation into bone cells remains a challenge. Graphene-based nanomaterials are attractive candidates for biomedical applications as substrates for stem cell (SC) differentiation, scaffolds in tissue engineering, and components of implant devices owing to their biocompatible, transferable and implantable properties. This study examined the enhanced osteogenic differentiation of human mesenchymal stem cells (hMSCs) by reduced graphene oxide (rGO) nanoparticles (NPs), and rGO NPs was prepared by reducing graphene oxide (GO) with a hydrazine treatment followed by annealing in argon and hydrogen. The cytotoxicity profile of each particle was examined using a water-soluble tetrazolium-8 (WST-8) assay. At different time-points, a WST-8 assay, alkaline phosphatase (ALP) activity assay and alizarin red S (ARS) staining were used to determine the effects of rGO NPs on proliferation, differentiation and mineralization, respectively. The results suggest that graphene-based materials have potential as a platform for stem cells culture and biomedical applications.

Photoresponse of an electrically tunable ambipolar graphene infrared thermocouple.

We explore the photoresponse of an ambipolar graphene infrared thermocouple at photon energies close to or below monolayer graphene's optical phonon energy and electrostatically accessible Fermi energy levels. The ambipolar graphene infrared thermocouple consists of monolayer graphene supported by an infrared absorbing material, controlled by two independent electrostatic gates embedded below the absorber. Using a scanning infrared laser microscope, we characterize these devices as a function of carrier type and carrier density difference controlled at the junction between the two electrostatic gates. On the basis of these measurements, conducted at both mid- and near-infrared wavelengths, the primary detection mechanism can be modeled as a thermoelectric response. By studying the effect of different infrared absorbers, we determine that the optical absorption and thermal conduction of the substrate play the dominant role in the measured photoresponse of our devices. These experiments indicate a path toward hybrid graphene thermal detectors for sensing applications such as thermography and chemical spectroscopy.

Graphene/MoS2 hybrid technology for large-scale two-dimensional electronics.

Two-dimensional (2D) materials have generated great interest in the past few years as a new toolbox for electronics. This family of materials includes, among others, metallic graphene, semiconducting transition metal dichalcogenides (such as MoS2), and insulating boron nitride. These materials and their heterostructures offer excellent mechanical flexibility, optical transparency, and favorable transport properties for realizing electronic, sensing, and optical systems on arbitrary surfaces. In this paper, we demonstrate a novel technology for constructing large-scale electronic systems based on graphene/molybdenum disulfide (MoS2) heterostructures grown by chemical vapor deposition. We have fabricated high-performance devices and circuits based on this heterostructure, where MoS2 is used as the transistor channel and graphene as contact electrodes and circuit interconnects. We provide a systematic comparison of the graphene/MoS2 heterojunction contact to more traditional MoS2-metal junctions, as well as a theoretical investigation, using density functional theory, of the origin of the Schottky barrier height. The tunability of the graphene work function with electrostatic doping significantly improves the ohmic contact to MoS2. These high-performance large-scale devices and circuits based on this 2D heterostructure pave the way for practical flexible transparent electronics.