Graphene Dotaz Zobrazit nápovědu
The carbon nanomaterials and congeners, e.g., graphene or graphene oxide (GO), dispose of numerous unique properties, which are not necessarily intrinsic but might be related to a content of impurities. The oxidation step of GO synthesis introduces a considerable amount of metallic species. Therefore, large-scale purification is an actual scientific challenge. Here we describe new purification technique (salt‑washing), which is based on three consecutive steps: (a) aggregation of GO sheets with NaCl (b) washing of the aggregates and (c) removing of the salt to afford purified GO (swGO). The considerably improved purity of swGO was demonstrated by ICP and EPR spectroscopy. The microscopic methods (TEM with SEAD, AFM) proved that the salt-washing does not affect the morphology or concentration of defects, showing the aggregation of GO with NaCl is fully reversible. The eligibility of swGO for biomedical applications was tested using fibroblastic cell cultures. The determined IC50 values clearly show a strong correlation between the purity of samples and cytotoxicity. Although the purification decreases cytotoxicity of GO, the IC50 values are still low proving that cytotoxic effect is not only impurities-related but also an intrinsic property. These findings may represent a serious limitation for usage of GO in biomedical applications.
- MeSH
- chlorid sodný toxicita MeSH
- grafit * toxicita MeSH
- nanostruktury * MeSH
- oxidace-redukce MeSH
- Publikační typ
- časopisecké články MeSH
This review summarizes and discusses electrophoretic methods for the fabrication deposited graphene and graphene-based structures. Graphenes are commonly dispersed in organic solvents or in water. Deposition procedures are performed mostly under constant voltage and deposition time seems to be an important parameter for influence prepared graphene structures. It was shown that electrophoretically deposited graphene layers have excellent properties suitable for electrochemical sensors and biosensors construction, e.g. high electrical conductivity and large surface area. Electrophoretic deposition enables also preparation of material which combines graphene with metal nanoparticles or polymers.
Three-dimensional (3D) printing technology offers attractive possibilities for many fields. In electrochemistry, 3D printing technology has been used to fabricate customized 3D-printed electrodes as a platform to develop bio/sensing, energy generation and storage devices. Here, we use a 3D-printed graphene/polylactic (PLA) electrode made by additive manufacturing technology and immobilize horseradish peroxidase (HRP) to create a direct electron transfer enzyme-based biosensors for hydrogen peroxide detection. Gold nanoparticles are included in the system to confirm and facilitate heterogeneous electron transfer. This work opens a new direction for the fabrication of third-generation electrochemical biosensors using 3D printing technology, with implications for applications in the environmental and biomedical fields.
This study investigates an environmentally benign approach to generate platinum nanoparticles (Pt NP) supported on the reduced graphene oxide (RGO) by non-edible gum waste of gum kondagogu (GK). The reaction adheres to the green chemistry approach by using an aqueous medium and a nontoxic natural reductant-GK-whose abundant hydroxyl groups facilitate in the reduction process of platinum salt and helps as well in the homogenous distribution of ensued Pt NP on RGO sheets. Scanning Electron Microscopy (SEM) confirmed the formation of kondagogu gum/reduced graphene oxide framed spherical platinum nanoparticles (RGO-Pt) with an average particle size of 3.3 ± 0.6 nm, as affirmed by Transmission Electron Microscopy (TEM). X-ray Diffraction (XRD) results indicated that the Pt NPs formed are crystalline with a face-centered cubic structure, while morphological analysis by XRD and Raman spectroscopy revealed a simultaneous reduction of GO and Pt. The hydrogenation of 4-nitrophenol could be accomplished in the superior catalytic performance of RGO-Pt. The current strategy emphasizes a simple, fast and environmentally benign technique to generate low-cost gum waste supported nanoparticles with a commendable catalytic activity that can be exploited in environmental applications.
Over the last few years, the electrospinning technique has attracted significant attention for the production of novel nanofibrous materials. At the same time, the use of graphene oxide and the natural products extracted from plants and/or trees have become very popular in various fields of science. In this work, a new method for the production of nanofibers based on a combination of Gum Arabic (GA), as a natural tree gum exudate, PVA, as an environmentally-friendly stabilizer, and graphene oxide (GO) has been developed and characterized. SEM analysis showed fundamental differences on the surface of bare nanofibers with and without GO, and also significantly smaller fiber diameters in the case of the presence of GO (fibers <100 nm present). Raman spectroscopy confirmed and TGA analysis approximated the content of GO in the nanofibers. Adsorption of methylene blue on the produced nanofibrous membrane was about 50% higher in the presence of GO, which opens the possibility to use GO/GA/PVA fibers in several applications, for example for the removal of dyes.
- MeSH
- adsorpce MeSH
- arabská guma chemie MeSH
- chemické látky znečišťující vodu izolace a purifikace MeSH
- elektrochemické techniky MeSH
- grafit chemie MeSH
- kinetika MeSH
- lidé MeSH
- methylenová modř izolace a purifikace MeSH
- nanovlákna chemie ultrastruktura MeSH
- polyvinyly chemie MeSH
- velikost částic MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Our recent experience of the COVID-19 pandemic has highlighted the importance of easy-to-use, quick, cheap, sensitive and selective detection of virus pathogens for the efficient monitoring and treatment of virus diseases. Early detection of viruses provides essential information about possible efficient and targeted treatments, prolongs the therapeutic window and hence reduces morbidity. Graphene is a lightweight, chemically stable and conductive material that can be successfully utilized for the detection of various virus strains. The sensitivity and selectivity of graphene can be enhanced by its functionalization or combination with other materials. Introducing suitable functional groups and/or counterparts in the hybrid structure enables tuning of the optical and electrical properties, which is particularly attractive for rapid and easy-to-use virus detection. In this review, we cover all the different types of graphene-based sensors available for virus detection, including, e.g., photoluminescence and colorimetric sensors, and surface plasmon resonance biosensors. Various strategies of electrochemical detection of viruses based on, e.g., DNA hybridization or antigen-antibody interactions, are also discussed. We summarize the current state-of-the-art applications of graphene-based systems for sensing a variety of viruses, e.g., SARS-CoV-2, influenza, dengue fever, hepatitis C virus, HIV, rotavirus and Zika virus. General principles, mechanisms of action, advantages and drawbacks are presented to provide useful information for the further development and construction of advanced virus biosensors. We highlight that the unique and tunable physicochemical properties of graphene-based nanomaterials make them ideal candidates for engineering and miniaturization of biosensors.
- MeSH
- Betacoronavirus genetika izolace a purifikace patogenita MeSH
- biosenzitivní techniky * přístrojové vybavení metody trendy MeSH
- design vybavení MeSH
- DNA virů analýza genetika MeSH
- elektrochemické techniky MeSH
- grafit * chemie MeSH
- hybridizace nukleových kyselin MeSH
- klinické laboratorní techniky * přístrojové vybavení metody statistika a číselné údaje MeSH
- kolorimetrie MeSH
- koronavirové infekce diagnóza epidemiologie virologie MeSH
- kvantové tečky chemie MeSH
- lidé MeSH
- luminiscence MeSH
- nanostruktury chemie MeSH
- pandemie MeSH
- povrchová plasmonová rezonance MeSH
- Ramanova spektroskopie MeSH
- reakce antigenu s protilátkou MeSH
- virologie metody MeSH
- virová pneumonie diagnóza epidemiologie virologie MeSH
- viry genetika izolace a purifikace patogenita MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The synergetic effect of hydrophilic and hydrophobic carbon can be used to obtain tunable hydrogen evolution reaction (HER) at the interface. Herein, graphene oxide (GO-Hummers method) was coated on graphene foam (GF) synthesized via chemical vapor deposition to develop mixed-dimensional heterostructure for the observation of HER. The porosity of GF not only provides an optimized diffusion coefficient for better mass transport but also modified surface chemistry (GF/GO-hydrophobic/hydrophilic interface), which results in an onset potential 50 mV and overpotential of 450 mV to achieve the current density 10 mA/cm2. The surface analysis shows that inherent functional groups at the surface played a key role in tuning the activity of hybrid, providing a pathway to introduce non-corrosive electrodes for water splitting.
Two-dimensional (2D) materials remain highly interesting for assembling three-dimensional (3D) structures, amongst others, in the form of macroscopic hydrogels. Herein, we present a novel approach for inducing chemical inter-sheet crosslinks via an ethylenediamine mediated reaction between Ti3C2Tx and graphene oxide in order to obtain a reduced graphene oxide-MXene (rGO-MXene) hydrogel. The composite hydrogels are hydrophilic with a stiffness of ~20 kPa. They also possess a unique inter-connected porous architecture, which led to a hitherto unprecedented ability of human cells across three different types, epithelial adenocarcinoma, neuroblastoma and fibroblasts, to form inter-connected three-dimensional networks. The attachments of the cells to the rGO-MXene hydrogels were superior to those of the sole rGO-control gels. This phenomenon stems from the strong affinity of cellular protrusions (neurites, lamellipodia and filopodia) to grow and connect along architectural network paths within the rGO-MXene hydrogel, which could lead to advanced control over macroscopic formations of cellular networks for technologically relevant bioengineering applications, including tissue engineering and personalized diagnostic networks-on-chip. STATEMENT OF SIGNIFICANCE: Conventional hydrogels are made of interconnected polymeric fibres. Unlike conventional case, we used hydrothermal and chemical approach to form interconnected porous hydrogels made of two-dimensional flakes from graphene oxide and metal carbide from a new family of MXenes (Ti3C2Tx). This way, we formed three-dimensional porous hydrogels with unique porous architecture of well-suited chemical surfaces and stiffness. Cells from three different types cultured on these scaffolds formed extended three-dimensional networks - a feature of extended cellular proliferation and pre-requisite for formation of organoids. Considering the studied 2D materials typically constitute materials exhibiting enhanced supercapacitor performances, our study points towards better understanding of design of tissue engineering materials for the future bioengineering fields including personalized diagnostic networks-on-chip, such as artificial heart actuators.
- MeSH
- grafit * MeSH
- hydrogely * MeSH
- lidé MeSH
- titan MeSH
- tkáňové inženýrství MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The increasing use of neonicotinoids in systematic seed treatment to crops is a serious cause of pollution of water resources and environment. Consequently, food sources can get eventually contaminated. To this end, it is desirable to develop suitable and effective platforms in order to obtain low-cost and sensitive sensors for neonicotinoids detection. In this work, graphene oxide modified electrodes were used as highly efficient electrochemical sensors for detection of two common insecticides - thiamethoxam and imidacloprid. The proposed sensor responded linearly in the concentration range of 10-200µmolL(-1) for both analytes and the detection limits were determined as low as 8.3µmolL(-1) and 7.9µmolL(-1) for thiamethoxam and imidacloprid, respectively. Analytical performance was also evaluated on spiked water and honey samples.
- MeSH
- analýza potravin ekonomika metody MeSH
- biosenzitivní techniky ekonomika metody MeSH
- chemické látky znečišťující vodu analýza MeSH
- dusíkaté sloučeniny analýza MeSH
- elektrochemické techniky ekonomika metody MeSH
- elektrody MeSH
- grafit chemie MeSH
- imidazoly analýza MeSH
- insekticidy analýza MeSH
- kontaminace potravin analýza MeSH
- limita detekce MeSH
- med analýza MeSH
- monitorování životního prostředí ekonomika metody MeSH
- oxaziny analýza MeSH
- oxidy chemie MeSH
- řeky chemie MeSH
- thiazoly analýza MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
The analytical performance of the clay paste electrode and graphene paste electrode was compared using square wave voltammetry (SWV) and cyclic voltammetry (CV). The comparison was made on the basis of a paracetamol (PA) determination on both working electrodes. The influence of pH and SWV parameters was investigated. The linear concentration ranges were found to be 6.0 × 10-7-3.0 × 10-5 and 2.0 × 10-6-8.0 × 10-5 mol L-1 for clay paste electrode (ClPE) and graphene paste electrode (GrPE), respectively. The detection and quantification limits were calculated as 1.4 × 10-7 and 4.7 ×10-7 mol L-1 for ClPE and 3.7 × 10-7 and 1.2 × 10-6 mol L-1 for GrPE, respectively. Developed methods were successfully applied to pharmaceutical formulations analyses. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize ClPE and GrPE surfaces. Clay composition was examined with wavelength dispersive X-ray (WDXRF).
