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Ece Eksin, Erhan Zor, Arzum Erdem, Haluk Bingol
Recently, the low-cost effective biosensing systems based on advanced nanomaterials have received a key attention for development of novel assays for rapid and sequence-specific nucleic acid detection. The electrochemical biosensor based on reduced graphene oxide (rGO) modified disposable pencil graphite electrodes (PGEs) were developed herein for electrochemical monitoring of DNA, and also for monitoring of biointeraction occurred between anticancer drug, Daunorubicin (DNR), and DNA. First, rGO was synthesized chemically and characterized by using UV-Vis, TGA, FT-IR, Raman Spectroscopy and SEM techniques...
February 11, 2017: Biosensors & Bioelectronics
Jiyoon Bu, Young Jun Kim, Yoon-Tae Kang, Tae Hee Lee, Jeongsuk Kim, Young-Ho Cho, Sae-Won Han
The metastasis of cancer is strongly associated with the spread of circulating tumor cells (CTCs). Based on the microfluidic devices, which offer rapid recovery of CTCs, a number of studies have demonstrated the potential of CTCs as a diagnostic tool. However, not only the insufficient specificity and sensitivity derived from the rarity and heterogeneity of CTCs, but also the high-cost fabrication processes limit the use of CTC-based medical devices in commercial. Here, we present a low-cost fabric sheet layers for CTC isolation, which are composed of polyester monofilament yarns...
February 12, 2017: Biomaterials
Kun Wang, Meng-Qi He, Fu-Heng Zhai, Rong-Huan He, Yong-Liang Yu
Simple, rapid, sensitive, and specific detection of cancer cells plays a pivotal role in the diagnosis and prognosis of cancer. A sandwich electrochemical biosensor was developed based on polyadenine (polydA)-aptamer modified gold electrode (GE) and polydA-aptamer functionalized gold nanoparticles/graphene oxide (AuNPs/GO) hybrid for the label-free and selective detection of breast cancer cells (MCF-7) via a differential pulse voltammetry (DPV) technique. Due to the intrinsic affinity between multiple consecutive adenines of polydA sequences and gold, polydA modified aptamer instead of thiol terminated aptamer was immobilized on the surface of GE and AuNPs/GO...
May 1, 2017: Talanta
Mumei Chen, Zheng Li, Jihao Li, Jingye Li, Qingnuan Li, Lan Zhang
A new approach for uranium extraction employing graphene aerogel (GA) as a skeleton loading organic solution (GA-LOS) is proposed and investigated. Firstly, the GA with super-hydrophobicity and high organic solution absorption capacity was fabricated by one-step reduction and self-assembly of graphene oxide with ethylenediamine. By adsorbing Tri-n-butyl phosphate (TBP)/n-dodecane solution to prepare GA-LOS, the extraction of U(VI) from nitric acid medium using GA-LOS was investigated and compared with conventional solvent extraction...
May 1, 2017: Talanta
Ojodomo J Achadu, Tebello Nyokong
The fabrication of maleimide-derivatized graphene quantum dots (M-GQDs) and zinc phthalocyanine (2) as novel sensor probes for the selective detection of biothiols (cysteine, homocysteine or glutathione) through the rapid and specific Michael addition reaction between biothiols and the maleimide-derivatized probes is presented in this study. GQDs directly functionalized with maleimide units (M-GQDs) were synthesized and deployed for biothiols recognition following the principle of Michael addition. M-GQDs probe was found to be highly sensitive and selective towards biothiols detection in the nanomolar range in aqueous solution and at physiological pH (7...
May 1, 2017: Talanta
Bingyuan Su, Huilin Shao, Na Li, Xiaomei Chen, Zhixiong Cai, Xi Chen
In this work, a sensitive bisphenol A (BPA) electrochemical sensor was assembled using a surfactant-free AuPd nanoparticles-loaded graphene nanosheets (AuPdNPs/GNs) modified electrode. The AuPdNPs monodispersed on GNs were successfully prepared by the spontaneous redox reaction between bimetallic precursors and GNs. Because no surfactant or halide ions were involved in the proposed synthesis, the prepared composite was enabled to directly modify a glassy carbon electrode without any pre-treatments. Moreover, due to the synergetic effect of Au and Pd, AuPdNPs/GNs displayed high electrochemical activity with well-defined voltammetric peaks of BPA oxidation and lower overpotential compared with monometallic PdNPs and AuNPs supported GNs...
May 1, 2017: Talanta
Afshan Omidvar, Babak Jaleh, Mahmoud Nasrollahzadeh
A GO/Pd nanocomposite has been successfully synthesized applying a simple method via immobilizing Pd on the surface of the graphene oxide (GO). The GO/Pd nanocomposite was characterized by X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) spectroscopy, Raman, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques. The surface morphology of Pd NPs was viewed by TEM, the particles are spherical with an average particle size of 11nm...
February 9, 2017: Journal of Colloid and Interface Science
Liusi Yang, Mingchu Zou, Shiting Wu, Wenjing Xu, Huaisheng Wu, Anyuan Cao
Graphene has a planar atomic structure with high flexibility, and might be used as ultra-thin conductive glues or adhesion layers in electronics and other applications. Here, we show that graphene oxide (GO) sheets condensed from solution can act as a pure, thin-layer, non-penetrating glue for fabrication of vertical architectures anchored on rigid and flexible substrates. Carbon nanotube (CNT) sponges are used as a porous template to make polymer-reinforced composite columns, to achieve both high conductivity and elastic behavior...
February 17, 2017: ACS Nano
Frank Ceballos, Ming-Gang Ju, Samuel D Lane, Xiao Cheng Zeng, Hui Zhao
Two dimensional materials, such as graphene and monolayer transition metal dichalcogenides, allow the fabrication of multilayer structures without lattice matching restriction. A central issue in developing such artificial materials is to understand and control the interlayer electron transfer process, which plays a key role in harvesting their emergent properties. Recent photoluminescence and transient absorption measurements revealed that the electron transfer in hetero-bilayers occurs on ultrafast time scales...
February 17, 2017: Nano Letters
Anirban Kundu, Renu Rani, Kiran S Hazra
The century-old controversy over two contradicting theories on radiation pressure of light proposed by Abraham and Minkowski can come to an end if there is a direct method to measure the surface deformation of the target material due to momentum transfer of photons. Here we have investigated the effect of radiation pressure on the surface morphology of Graphene Oxide (GO) film, experienced due to low power focused laser irradiation. In-depth investigation has been carried out to probe the bending of the GO surface due to radiation pressure by Atomic Force Microscopy (AFM) and subsequently the uniaxial strain induced on the GO film has been probed by Raman Spectroscopy...
February 13, 2017: Scientific Reports
Mu-Ying Wu, Dong-Xiong Ling, Lin Ling, William Li, Yong-Qing Li
Optical manipulation and label-free characterization of nanoscale structures open up new possibilities for assembly and control of nanodevices and biomolecules. Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped particle, but is generally less effective for individual nanoparticles. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap with confocal Raman spectroscopy...
February 17, 2017: Scientific Reports
M J Zhu, A V Kretinin, M D Thompson, D A Bandurin, S Hu, G L Yu, J Birkbeck, A Mishchenko, I J Vera-Marun, K Watanabe, T Taniguchi, M Polini, J R Prance, K S Novoselov, A K Geim, M Ben Shalom
An energy gap can be opened in the spectrum of graphene reaching values as large as 0.2 eV in the case of bilayers. However, such gaps rarely lead to the highly insulating state expected at low temperatures. This long-standing puzzle is usually explained by charge inhomogeneity. Here we revisit the issue by investigating proximity-induced superconductivity in gapped graphene and comparing normal-state measurements in the Hall bar and Corbino geometries. We find that the supercurrent at the charge neutrality point in gapped graphene propagates along narrow channels near the edges...
February 17, 2017: Nature Communications
Alexander Georgi, Peter Nemes-Incze, Ramon Carrillo-Bastos, Daiara Faria, Silvia Viola Kusminskiy, Dawei Zhai, Martin Schneider, Dinesh Subramaniam, Torge Mashoff, Nils Michael Freitag, Marcus Liebmann, Marco Pratzer, Ludger Wirtz, Colin R Woods, Roman Vladislavovich Gorbachev, Yang Cao, Kostya S Novoselov, Nancy Sandler, Markus Morgenstern
One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudo-magnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudo-magnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudo-magnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene's pseudospin due to a strain induced pseudo-magnetic field, in analogy to the alignment of a real spin in a magnetic field...
February 17, 2017: Nano Letters
Johannes Binder, Freddie Withers, Maciej R Molas, Clement Faugeras, Karol Nogajewski, Kenji Watanabe, Takashi Taniguchi, Aleksey Kozikov, Andre K Geim, Kostya S Novoselov, Marek Potemski
We report on experimental investigations of an electrically driven WSe2 based light-emitting van der Waals heterostructure. We observe a threshold voltage for electroluminescence significantly lower than the corresponding single particle band gap of monolayer WSe2. This observation can be interpreted by considering the Coulomb interaction and a tunneling process involving excitons, well beyond the picture of independent charge carriers. An applied magnetic field reveals pronounced magneto-oscillations in the electroluminescence of the free exciton emission intensity with a 1/B-periodicity...
February 17, 2017: Nano Letters
Yong Long, Kai Wang, Guolei Xiang, Kai Song, Gang Zhou, Xun Wang
Highly selective macromembranes, fabricated by cation-decorated graphene oxide, exhibit an excellent selectivity toward a wide range of solvents. Mixed solvents are successfully separated, based on which a membrane reactor is designed to promote a series of chemical reactions. The cations bonding to the graphene oxide nanosheets are found to be responsible for this selectivity by cation-π, electrostatic interactions, and hydrogen bonding.
February 17, 2017: Advanced Materials
Nur Afifah Zubair, Norizah Abdul Rahman, Hong Ngee Lim, Yusran Sulaiman
Electrically conductive nanofiber is well known as an excellent nanostructured material for its outstanding performances. In this work, poly(3,4-ethylenedioxythiophene) (PEDOT)-coated polyvinyl alcohol-graphene oxide (PVA-GO)-conducting nanofibers were fabricated via a combined method using electrospinning and electropolymerization techniques. During electrospinning, the concentration of PVA-GO solution and the applied voltage were deliberately altered in order to determine the optimized electrospinning conditions...
December 2017: Nanoscale Research Letters
Xiaoxing Zhang, Hao Cui, Yingang Gui
Graphene-based materials have aroused enormous focus on a wide range of engineering fields because of their unique structure. One of the most promising applications is gas adsorption and sensing. In electrical engineering, graphene-based sensors are also employed as detecting devices to estimate the operation status of gas insulated switchgear (GIS). This paper reviews the main synthesis methods of graphene, gas adsorption, and sensing mechanism of its based sensors, as well as their applications in detecting SF6 decomposing products, such as SO2, H2S, SO2F2, and SOF2, in GIS...
February 13, 2017: Sensors
Tao Chen, Yuanhong Xu, Zhi Peng, Aihua Li, Jingquan Liu
Simultaneously enhancing the catalytic bioactivity and stability of enzyme is still an intractable issue in the enzymatic study. Herein, a facile and effective approach was designed to immobilize and modify laccase on a Cu(2+)-adsorbed pyrene-terminated block copolymer [poly(acrylic acid)/poly(poly(ethylene glycol) acrylate)] (PAA/PPEGA), which was prepared via well-controlled reversible addition-fragmentation chain transfer polymerization. PAA provided the supporting matrix for firm immobilization of Cu(2+), an enzyme bioactivity inducer, onto the microstructure of laccase, while avoiding any contamination of the heavy metal Cu(2+) into the following application system...
February 7, 2017: Analytical Chemistry
Song Wang, Yajun Zhang, Guangsheng Pang, Yingwei Zhang, Shaojun Guo
The design of graphene quantum dots (GQDs)-aptamer bioconjugates as the new sensing platform is very important for developing high-sensitivity fluorescent biosensors; however, achieving new bioconjugates is still a great challenge. Herein, we report the development of a new high-sensitivity fluorescent aptasensor for the detection of ochratoxin A (OTA) based on tuning aggregation/disaggregation behavior of GQDs by structure-switching aptamers. The fluorescence sensing process for OTA detection involved two key steps: (1) cDNA-aptamer (cDNA, complementary to part of the OTA aptamer) hybridization induced the aggregation of GQD (fluorescence quenching) after cDNA was added into the GQDs-aptamer bioconjugate solution, and (2) the target of OTA triggered disaggregation of GQD aggregates (fluorescence recovery)...
February 7, 2017: Analytical Chemistry
Jianqiang Zhu, Ming Xu, Ming Gao, Zhihong Zhang, Yong Xu, Tian Xia, Sijin Liu
The outstanding physicochemical properties endow graphene materials (e.g. graphene oxide, GO) with beneficial potentials in diverse biomedical fields such as bioimaging, drug delivery and biomolecular detection. GO recently emerges to act as chemosensitizer; however, the detailed molecular bases underlying GO-conducted sensitization and according biological effects are still elusive. Based on our recent findings that GO treatment at sublethal concentrations could impair the general cellular priming state including disorders of plasma membrane and cytoskeleton construction, we here aimed to explore the mechanism of GO as a sensitizer to make cancer cells more susceptible to chemotherapeutic agents...
February 16, 2017: ACS Nano
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