Displaying publications 121 - 133 of 133 in total

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  1. Fulltext Investigation of graphene-on-metal substrates for SPR-based sensor using finite-difference time domain
    Said FA, Menon PS, Rajendran V, Shaari S, Majlis BY
    IET Nanobiotechnol, 2017 Dec;11(8):981-986.
    PMID: 29155398 DOI: 10.1049/iet-nbt.2017.0051
    In this study, the authors investigated the effects of a single layer graphene as a coating layer on top of metal thin films such as silver, gold, aluminum and copper using finite-difference time domain method. To enhance the resolution of surface plasmon resonance (SPR) sensor, it is necessary to increase the SPR reflectivity and decrease the full-width-half maximum (FWHM) of the SPR curve so that there is minimum uncertainty in the determination of the resonance dip. Numerical data was verified with analytical and experimental data where all the data were in good agreement with resonance angle differing in <10% due to noise present in components such as humidity and temperature. In further analysis, reflectivity and FWHM were compared among four types of metal with various thin film thicknesses where graphene was applied on top of the metal layers, and data was compared against pure conventional metal thin films. A 60 nm-thick Au thin film results in higher performance with reflectivity of 92.4% and FWHM of 0.88° whereas single layer graphene-on-60 nm-thick Au gave reflectivity of 91.7% and FWHM of 1.32°. However, a graphene-on-40 nm-thick Ag also gave good performance with narrower FWHM of 0.88° and reflection spectra of 89.2%.
    Matched MeSH terms: Graphite/chemistry*
  2. Fulltext Reduced graphene oxide anodes for potential application in algae biophotovoltaic platforms
    Ng FL, Jaafar MM, Phang SM, Chan Z, Salleh NA, Azmi SZ, et al.
    Sci Rep, 2014;4:7562.
    PMID: 25531093 DOI: 10.1038/srep07562
    The search for renewable energy sources has become challenging in the current era, as conventional fuel sources are of finite origins. Recent research interest has focused on various biophotovoltaic (BPV) platforms utilizing algae, which are then used to harvest solar energy and generate electrical power. The majority of BPV platforms incorporate indium tin oxide (ITO) anodes for the purpose of charge transfer due to its inherent optical and electrical properties. However, other materials such as reduced graphene oxide (RGO) could provide higher efficiency due to their intrinsic electrical properties and biological compatibility. In this work, the performance of algae biofilms grown on RGO and ITO anodes were measured and discussed. Results indicate improved peak power of 0.1481 mWm(-2) using the RGO electrode and an increase in efficiency of 119%, illustrating the potential of RGO as an anode material for applications in biofilm derived devices and systems.
    Matched MeSH terms: Graphite/chemistry*
  3. Fulltext Mechanical and in vitro biological performance of graphene nanoplatelets reinforced calcium silicate composite
    Mehrali M, Moghaddam E, Seyed Shirazi SF, Baradaran S, Mehrali M, Latibari ST, et al.
    PLoS One, 2014;9(9):e106802.
    PMID: 25229540 DOI: 10.1371/journal.pone.0106802
    Calcium silicate (CaSiO3, CS) ceramic composites reinforced with graphene nanoplatelets (GNP) were prepared using hot isostatic pressing (HIP) at 1150°C. Quantitative microstructural analysis suggests that GNP play a role in grain size and is responsible for the improved densification. Raman spectroscopy and scanning electron microscopy showed that GNP survived the harsh processing conditions of the selected HIP processing parameters. The uniform distribution of 1 wt.% GNP in the CS matrix, high densification and fine CS grain size help to improve the fracture toughness by ∼130%, hardness by ∼30% and brittleness index by ∼40% as compared to the CS matrix without GNP. The toughening mechanisms, such as crack bridging, pull-out, branching and deflection induced by GNP are observed and discussed. The GNP/CS composites exhibit good apatite-forming ability in the simulated body fluid (SBF). Our results indicate that the addition of GNP decreased pH value in SBF. Effect of addition of GNP on early adhesion and proliferation of human osteoblast cells (hFOB) was measured in vitro. The GNP/CS composites showed good biocompatibility and promoted cell viability and cell proliferation. The results indicated that the cell viability and proliferation are affected by time and concentration of GNP in the CS matrix.
    Matched MeSH terms: Graphite/chemistry*
  4. Fulltext Mechanical and Chemical Characterization of a TiC/C System Synthesized Using a Focus Plasma Arc
    Mahmoodian R, Hamdi M, Hassan MA, Akbari A
    PLoS One, 2015;10(6):e0130836.
    PMID: 26111217 DOI: 10.1371/journal.pone.0130836
    Titanium carbide-graphite (TiC/C) composite was successfully synthesized from Ti and C starting elemental powders using self-propagating high-temperature synthesis technique in an ultra-high plasma inert medium in a single stage. The TiC was exposed to a high-temperature inert medium to allow recrystallization. The product was then characterized using field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Rietveld refinement, nanoindentation, and micro-hardness to determine the product's properties. The recorded micro-hardness of the product was 3660 HV, which is a 14% enhancement and makes is comparable to TiC materials.
    Matched MeSH terms: Graphite/chemistry*
  5. Novel alkaline-reduced cuprous oxide/graphene nanocomposites for non-enzymatic amperometric glucose sensor application
    Yazid SNAM, Isa IM, Hashim N
    Mater Sci Eng C Mater Biol Appl, 2016 Nov 01;68:465-473.
    PMID: 27524043 DOI: 10.1016/j.msec.2016.06.006
    This paper presents the fabrication of a highly sensitive and selective glucose sensor based on cuprous oxide/graphene nanocomposites-modified glassy carbon electrode (Cu2O/graphene/GCE). The Cu2O/graphene nanocomposites were synthesized based on a simple and straightforward chemical reduction process in alkaline aqueous solution using sodium carbonate as reductant. The size and shape of Cu2O nanoparticles on graphene sheets can be controlled by changing the amount of graphene oxide added during reaction. The electrochemical properties of Cu2O/graphene/GCE in 0.1M phosphate buffer solution were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. It was found that the pH, concentration of supporting electrolyte, and scan rate had very crucial effect on the sensitivity of prepared sensor towards glucose oxidation. At an applied potential of +0.50V, the Cu2O/graphene/GCE presented a high sensitivity of 1330.05μAmM(-1)cm(-2) and fast response (within 3s). The amperometric non-enzymatic glucose sensor developed had a linear relationship from 0.01mM to 3.0mM glucose and detection limit of 0.36μM. In the presence of ascorbic acid, uric acid, dopamine, chloride and citrate ion and other carbohydrates, the interferences were negligible. The proposed sensor was successfully applied for the determination of glucose concentration in real human blood samples.
    Matched MeSH terms: Graphite/chemistry*
  6. Fulltext A Novel Adsorbent Magnetic Graphene Oxide Modified with Chitosan for the Simultaneous Reduction of Mycotoxins
    Abbasi Pirouz A, Abedi Karjiban R, Abu Bakar F, Selamat J
    Toxins (Basel), 2018 09 06;10(9).
    PMID: 30200553 DOI: 10.3390/toxins10090361
    A novel magnetic graphene oxide modified with chitosan (MGO-CTS) was synthesised as an adsorbent aimed to examine the simultaneous removal of mycotoxins. The composite was characterised by various procedures, namely Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and a scanning electron microscope (SEM). The adsorption evaluation was considered via pH effects, initial mycotoxin concentration, adsorption time and temperature. Adsorption isotherm data and kinetics experiments were acquired at the optimum pH 5 fit Freundlich isotherm as well as pseudo-second-order kinetic models. The thermodynamic results indicated that the adsorption of the mycotoxins was spontaneous, endothermic and favourable.
    Matched MeSH terms: Graphite/chemistry*
  7. Graphene-based electrochemical biosensors for monitoring noncommunicable disease biomarkers
    Taniselass S, Arshad MKM, Gopinath SCB
    Biosens Bioelectron, 2019 Apr 01;130:276-292.
    PMID: 30771717 DOI: 10.1016/j.bios.2019.01.047
    Graphene is a 2-dimensional nanomaterial with an atomic thickness has attracted a strong scientific interest owing to their remarkable optical, electronic, thermal, mechanical and electrochemical properties. Graphene-based materials particularly graphene oxide and reduced graphene oxide are widely utilized in various applications ranging from food industry, environmental monitoring and biomedical fields as well as in the development of various types of biosensing devices. The richness in oxygen functional groups in the materials serves as a catalysis for the development of biosensors/electrochemical biosensors which promotes for an attachment of biological recognition elements, surface functionalization and compatible with micro- and nano- bio-environment. In this review, the graphene-based materials application in electrochemical biosensors based on recent advancement (e.g; the surface modification and analytical performances) and the utilization of such biosensors to monitor the noncommunicable diseases are presented. The detection performances of the graphene-based electrochemical biosensors are in the range of ng/mL and have reached up to fg/mL in detecting the targets of NCDs with higher selectivity, sensitivity and stability with good reproducibility attributes. We have discussed the advances while addressing the very specific biomarkers for the NCDs detection. Challenges and possible future research directions for the NCDs detection based on graphene nanocomposite with other 2D nanomaterials are outlined.
    Matched MeSH terms: Graphite/chemistry
  8. 2D Graphene oxide (GO) doped p-n type BiOI/Bi2WO6 as a novel composite for photodegradation of bisphenol A (BPA) in aqueous solutions under UV-vis irradiation
    Mengting Z, Kurniawan TA, Yanping Y, Avtar R, Othman MHD
    Mater Sci Eng C Mater Biol Appl, 2020 Mar;108:110420.
    PMID: 31924000 DOI: 10.1016/j.msec.2019.110420
    Bisphenol A (BPA) is a refractory pollutant presents in water body that possesses serious threats to living organisms. To deal with it, we investigate and evaluate the effectiveness of GO@BiOI/Bi2WO6 composite as a novel photocatalyst for BPA removal from aqueous solutions under UV-vis irradiation. To enhance its removal for BPA, the surface of BiOI/Bi2WO6 is modified with graphene oxide (GO). This composite is named as 'GO@BiOI/Bi2WO6'. Changes in its physico-chemical properties after surface modification with GO are characterized by XRD, FTIR, FESEM-EDS, XPS, PL, and BET methods. Optimized conditions of BPA degradation by the composite are determined under identical conditions. Photodegradation pathways of BPA and its removal mechanisms by the same composite are presented. It is obvious that the GO@BiOI/Bi2WO6 has demonstrated its potential as a promising photocatalyst for BPA removal under UV-vis irradiation. About 81% of BPA removal is attained by the GO@BiOI/Bi2WO6 under optimized conditions (10 mg/L of BPA, 0.5 g/L of dose, pH 7 and 5 h of reaction time). The oxidation by-products of BPA degradation include p-hydroquinone or 4-(1-hydroxy-1-methyl-ethyl)-phenol. In spite of its performance, the treated effluents are still unable to meet the maximum discharge limit of <1 mg/L set by national legislation. Therefore, subsequent biological processes are essential to maximize its biodegradation in the wastewater samples before their discharge into waterbody.
    Matched MeSH terms: Graphite/chemistry*
  9. Fulltext Optical and Thermal Properties of Laser-Ablated Platinum Nanoparticles Graphene Oxide Composite
    Sadrolhosseini AR, Habibiasr M, Shafie S, Solaimani H, Lim HN
    Int J Mol Sci, 2019 Dec 06;20(24).
    PMID: 31817593 DOI: 10.3390/ijms20246153
    Platinum nanoparticles were synthesized in graphene oxide aqueous solution using a laser ablation technique to investigate the effect of optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution. The samples were prepared with different ablation times. The platinum nanoparticles that formed a spherical shape on the surface of graphene oxide solution were authenticated using UV-visible spectrum and transmission electron microscopy patterns. The particle size decreased with increasing ablation time, and the concentration and volume fraction of samples were increased. To obtain the optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution, UV-visible spectroscopy, Z-scan, thermal lens and photoacoustic techniques were used. Consequently, the linear and nonlinear refractive indices increased with an increase in the volume fraction of platinum nanoparticles. It was observed from the spatial self-phase modulation patterns that, the optical nonlinear property of the graphene oxide was enhanced in the presence of platinum nanoparticles, and the nonlinearity increased with an increase in the volume fraction of platinum nanoparticles inside the graphene oxide solution. The thermal diffusivity and thermal effusivity of platinum nanoparticles graphene oxide were measured using a thermal lens and photoacoustic methods, respectively. The thermal diffusivity and thermal effusivity of samples were in the range of 0.0341 × 10-5 m2/s to 0.1223 × 10-5 m2/s and 0.163 W s1/2 cm-2 K-1 to 0.3192 W s1/2 cm-2 K-1, respectively. Consequently, the platinum enhanced the optical and thermal properties of graphene oxide.
    Matched MeSH terms: Graphite/chemistry*
  10. Fulltext An investigation of the stirring duration effect on synthesized graphene oxide for dye-sensitized solar cells
    Yau XH, Low FW, Khe CS, Lai CW, Tiong SK, Amin N
    PLoS One, 2020;15(2):e0228322.
    PMID: 32012195 DOI: 10.1371/journal.pone.0228322
    This study investigates the effects of stirring duration on the synthesis of graphene oxide (GO) using an improved Hummers' method. Various samples are examined under different stirring durations (20, 40, 60, 72, and 80 h). The synthesized GO samples are evaluated through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The GO sample with 72 h stirring duration (GO72) has the highest d-spacing in the XRD results, highest atomic percentage of oxygen in EDX (49.57%), highest intensity of oxygen functional group in FTIR spectra, and highest intensity ratio in Raman analysis (ID/IG = 0.756). Results show that GO72 with continuous stirring has the highest degree of oxidation among other samples. Electrochemical impedance spectroscopy analysis shows that GO72-titanium dioxide (TiO2) exhibits smaller charge transfer resistance and higher electron lifetime compared with the TiO2-based photoanode. The GO72 sample incorporating TiO2 nanocomposites achieves 6.25% photoconversion efficiency, indicating an increase of more than twice than that of the mesoporous TiO2 sample. This condition is fully attributed to the efficient absorption rate of nanocomposites and the reduction of the recombination rate of TiO2 by GO in dye-sensitized solar cells.
    Matched MeSH terms: Graphite/chemistry*
  11. Fulltext Exceedingly biocompatible and thin-layered reduced graphene oxide nanosheets using an eco-friendly mushroom extract strategy
    Muthoosamy K, Bai RG, Abubakar IB, Sudheer SM, Lim HN, Loh HS, et al.
    Int J Nanomedicine, 2015;10:1505-19.
    PMID: 25759577 DOI: 10.2147/IJN.S75213
    PURPOSE: A simple, one-pot strategy was used to synthesize reduced graphene oxide (RGO) nanosheets by utilizing an easily available over-the-counter medicinal and edible mushroom, Ganoderma lucidum.

    METHODS: The mushroom was boiled in hot water to liberate the polysaccharides, the extract of which was then used directly for the reduction of graphene oxide. The abundance of polysaccharides present in the mushroom serves as a good reducing agent. The proposed strategy evades the use of harmful and expensive chemicals and avoids the typical tedious reaction methods.

    RESULTS: More importantly, the mushroom extract can be easily separated from the product without generating any residual byproducts and can be reused at least three times with good conversion efficiency (75%). It was readily dispersible in water without the need of ultrasonication or any surfactants; whereas 5 minutes of ultrasonication with various solvents produced RGO which was stable for the tested period of 1 year. Based on electrochemical measurements, the followed method did not jeopardize RGO's electrical conductivity. Moreover, the obtained RGO was highly biocompatible to not only colon (HT-29) and brain (U87MG) cancer cells, but was also viable towards normal cells (MRC-5).

    CONCLUSION: Besides being eco-friendly, this mushroom based approach is easily scalable and demonstrates remarkable RGO stability and biocompatibility, even without any form of functionalization.

    Matched MeSH terms: Graphite/chemistry*
  12. Development of graphene based nanocomposites towards medical and biological applications
    Mousavi SM, Low FW, Hashemi SA, Lai CW, Ghasemi Y, Soroshnia S, et al.
    Artif Cells Nanomed Biotechnol, 2020 Dec;48(1):1189-1205.
    PMID: 32930615 DOI: 10.1080/21691401.2020.1817052
    Graphene and its derivative materials present high potential towards medical and biological applications, including drug delivery and bioimaging, due to their exceptional properties such as thermal conductivity and high specific surface area. The main focus of this work is to review the current development of graphene materials and the derivatives for biocompatible, bioimaging and drug delivery applications. Also, the synthesis methods with variation of graphene nanocomposites and the functionalisation will be further explained. For the graphene approaches, chemical vapour deposition (CVD) is the best-known technique to make high-quality graphene sheet by growth route with mass production. By considering the organic graphene nanocomposites, the biocompatibility and cytotoxic effects against graphene nanocomposites were evaluated for biomedical employments such as high quality bioimaging and effective drug delivery for cancer treatments. For example, graphene oxide incorporated with PEG and loaded with SN 38 for camptothecin analolgue as anticancer drug and revealed high cytotoxicity has an effect of 1000 times better effect than CPT in HCT-116 cells. Their drug delivery ability for both in-vivo and in-vitro applications compared to the controlled drugs such as doxorubicin (DOX) will be discussed accordingly. The graphene and its deriavatives possess some intriguing properties, which will lead to drug delivery due to strong biocompatibility and cyctotoxic effect towards biomedicine applications.
    Matched MeSH terms: Graphite/chemistry*
  13. A review of the applications of organo-functionalized magnetic graphene oxide nanocomposites for heavy metal adsorption
    Sherlala AIA, Raman AAA, Bello MM, Asghar A
    Chemosphere, 2018 Feb;193:1004-1017.
    PMID: 29874727 DOI: 10.1016/j.chemosphere.2017.11.093
    Graphene-based adsorbents have attracted wide interests as effective adsorbents for heavy metals removal from the environment. Due to their excellent electrical, mechanical, optical and transport properties, graphene and its derivatives such as graphene oxide (GO) have found various applications. However, in many applications, surface modification is necessary as pristine graphene/GO may be ineffective in some specific applications such as adsorption of heavy metal ions. Consequently, the modification of graphene/GO using various metals and non-metals is an ongoing research effort in the carbon-material realm. The use of organic materials represents an economical and environmentally friendly approach in modifying GO for environmental applications such as heavy metal adsorption. This review discusses the applications of organo-functionalized GO composites for the adsorption of heavy metals. The aspects reviewed include the commonly used organic materials for modifying GO, the performance of the modified composites in heavy metals adsorption, effects of operational parameters, adsorption mechanisms and kinetic, as well as the stability of the adsorbents. Despite the significant research efforts on GO modification, many aspects such as the interaction between the functional groups and the heavy metal ions, and the quantitative effect of the functional groups are yet to be fully understood. The review, therefore, offers some perspectives on the future research needs.
    Matched MeSH terms: Graphite/chemistry*
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