Carbon-based quantum particles, especially spherical carbon quantum dots (CQDs) and nanosheets like graphene quantum dots (GQDs), are an emerging class of quantum dots with unique properties owing to ...their quantum confinement effect. Many reviews appeared recently in the literature highlighting their optical properties, structures, and applications. These papers cover a broad spectrum of carbon-based nanoparticles, excluding a more detailed discussion about some important aspects related to the definition of carbon-based particles and the correlation of optical and electrochemical aspects in relation to sensing and biomedical applications. A large part of this review is devoted to these aspects. It aims, in particular, to act as a bridge between optical and electrochemical aspects of carbon-based quantum particles, both of which are associated with the electronic nature of carbon-based quantum particles. A special focus will be on their use in electroanalysis, notably their benefits in redox, and in electrochemical analysis with emphasis on their application as sensors. Electroanalysis is an easy and cost-effective means of providing qualitative and quantitative information of a specific analyte in solution in a time scale of some minutes. The integration of carbon-based quantum particles into these detection schemes as well as their incorporation into composite nanomaterials have largely improved detection limits with possibilities for their integration in aspects ranging from point-of-care devices to personalized medicine. This review will focus on some of these aspects while also covering the nanomedical aspects of carbon-based quantum particles, ultimately correlated for such developments.
Carbon-based quantum particles, especially spherical carbon quantum dots (CQDs) and nanosheets like graphene quantum dots (GQDs), are an emerging class of quantum dots with unique properties owing to their quantum confinement effect.
The study of graphene-based carbon nanocomposites has remarkably increased in recent years. Functionalized graphene-based nanostructures, including graphene oxide and reduced graphene oxide, have ...great potential as new innovative electrode materials in the fabrication of novel electrochemical sensors. Electrochemical sensors based on aptamers attracted great attention because of their high sensitivity and selectivity, and simple instrumentation, as well as low production cost. Aptamers as a potent alternative to antibodies are functional nucleic acids with a high tendency to specific analytes. Electrochemical aptasensors show specific recognition ability for a wide range of analytes. Although aptamers are selected in vitro in contrast to antibodies, they are interesting due to advantages like high stability, easy chemical modifications, and the potential to be employed in nanostructured device fabrication or electrochemical sensing devices. Recently, new nanomaterials have shown a significant impact on the production of electrochemical sensors with high efficiency and performance. This review aims to give an outline of electrochemical aptasensors based on the graphene family materials and discuss the detection mechanism in this type of aptasensors. The present review summarizes some of the recent achievements in graphene-based aptasensors and includes their recent electroanalytical applications.
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•A new voltammetric sensor for pH monitoring based on glassy carbon electrode incorporating poly-dopamine thin film demonstrated.•The analysis was performed based on the ...electro-oxidation of catechol moieties of poly-dopamine.•The developed system displays very promising performances, with a reproducible Nernstian response to pH changes.
This paper describes the development of a new voltammetric pH-sensor based on glassy carbon electrode incorporating poly-dopamine thin film. The sensor was fabricated under ambient conditions from voltammetric polymerization of the dopamine at the surface of glassy carbon electrode in aqueous media. The analysis was performed based on the electro-oxidation of catechol moieties of poly-dopamine. Cyclic voltammograms recorded in various buffer solutions (pH 1.0–12.0) yielded a distinct and unambiguous oxidation process through which to ascribe the peak potential with Nernstian (−58.2±0.09mV/pH) manner (T at 25°C). It is based on a 2 proton, 2 electron system over the aqueous pH range 1.0–12.0. The developed system displays very promising performances in buffered and unbuffered solutions, with a reproducible Nernstian response to pH changes. The effect the composition and concentration of buffer solutions have been investigated.
Bacterial infections remain one of the principal causes of morbidity and mortality worldwide. The number of deaths due to infections is declining every year by only 1% with a forecast of 13 million ...deaths in 2050. Among the 1400 recognized human pathogens, the majority of infectious diseases is caused by just a few, about 20 pathogens only. While the development of vaccinations and novel antibacterial drugs and treatments are at the forefront of research, and strongly financially supported by policy makers, another manner to limit and control infectious outbreaks is targeting the development and implementation of early warning systems, which indicate qualitatively and quantitatively the presence of a pathogen. As toxin contaminated food and drink are a potential threat to human health and consequently have a significant socioeconomic impact worldwide, the detection of pathogenic bacteria remains not only a big scientific challenge but also a practical problem of enormous significance. Numerous analytical methods, including conventional culturing and staining techniques as well as molecular methods based on polymerase chain reaction amplification and immunological assays, have emerged over the years and are used to identify and quantify pathogenic agents. While being highly sensitive in most cases, these approaches are highly time, labor, and cost consuming, requiring trained personnel to perform the frequently complex assays. A great challenge in this field is therefore to develop rapid, sensitive, specific, and if possible miniaturized devices to validate the presence of pathogens in cost and time efficient manners. Electrochemical sensors are well accepted powerful tools for the detection of disease-related biomarkers and environmental and organic hazards. They have also found widespread interest in the last years for the detection of waterborne and foodborne pathogens due to their label free character and high sensitivity. This Review is focused on the current electrochemical-based microorganism recognition approaches and putting them into context of other sensing devices for pathogens such as culturing the microorganism on agar plates and the polymer chain reaction (PCR) method, able to identify the DNA of the microorganism. Recent breakthroughs will be highlighted, including the utilization of microfluidic devices and immunomagnetic separation for multiple pathogen analysis in a single device. We will conclude with some perspectives and outlooks to better understand shortcomings. Indeed, there is currently no adequate solution that allows the selective and sensitive binding to a specific microorganism, that is fast in detection and screening, cheap to implement, and able to be conceptualized for a wide range of biologically relevant targets.
The mammalian mitochondrial inner membrane fusion protein OPA1 is controlled by complex patterns of alternative splicing and proteolysis. A subset of OPA1 isoforms is constitutively cleaved by YME1L. ...Other isoforms are not cleaved by YME1L, but they are cleaved when mitochondria lose membrane potential or adenosine triphosphate. In this study, we show that this inducible cleavage is mediated by a zinc metalloprotease called OMA1. We find that OMA1 small interfering RNA inhibits inducible cleavage, helps retain fusion competence, and slows the onset of apoptosis, showing that OMA1 controls OPA1 cleavage and function. We also find that OMA1 is normally cleaved from 60 to 40 kD by another as of yet unidentified protease. Loss of membrane potential causes 60-kD protein to accumulate, suggesting that OMA1 is attenuated by proteolytic degradation. We conclude that a proteolytic cascade controls OPA1. Inducible cleavage provides a mechanism for quality control because proteolytic inactivation of OPA1 promotes selective removal of defective mitochondrial fragments by preventing their fusion with the mitochondrial network.
In this research, we introduced the manganese ferrite/tungsten disulfide as novel catalyst by modification of MnFe2O4 with WS2 for the first time. The desired catalyst identified by different ...techniques and was used in the photocatalytic reduction reaction of a wide range of nitroaromatic compounds using N2H4.H2O at 25 °C. The results of the catalytic photoreduction reaction of nitrobenzene, 1,2-dinitrobenzene and 1,4-dinitrobenzene were superb and showed 100% efficiency within 10 min. This novel photocatalyst represented high magnetic recycling and reusability performance for the reduction reactions even after 20 times of reuse.
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•Excellent efficiency in photoreduction of nitroaromatic compounds in comparison with the literature.•A novel binary composite based on WS2 and MnFe2O4.•Simple separation of catalyst from the reaction in the presence of small external magnet and using it for several times•Photoreduction of nitroaromatic compounds at ambient temperature.•Good stability with 100% conversion of catalyst after 20th reuses.
Electrolysis is one of the clean, environmentally friendly, and sustainable pathways to produce hydrogen for renewable energy storage. However, to make electrolysis a competitive technology for ...hydrogen production, developing nonprecious metal‐based catalysts for oxygen evolution reaction (OER) is mandatory. Several new classes of electrocatalysts are developed with outstanding OER catalytic activity, stability, and commercial viability. Owing to the structural diversity, porosity, and accessibility of catalytically active metal centers, nickel‐based metal–organic frameworks (MOFs) are intensively explored as OER catalysts. In particular, bi‐ and trimetallic Ni MOFs with Fe and Co as additional metal nodes show excellent OER activity which can be tailored through the fine tuning of the metal compositions. Herein, the current state of research in Ni‐based MOFs as OER catalyst materials for alkaline electrolysis is presented. Strategies to improve the catalytic performance like compositional variations, choice of synthetic routes, and support materials are presented. Furthermore, OER activities are compared and presented based on the performance metrics (current density, overpotential, and Tafel slopes). Finally, concluding remarks featuring the key findings in Ni‐based MOFs and the possible rooms for future developments are summarized.
The review recaps the growing interest in Ni–Co and Ni–Fe metal‐organic frame works (MOFs) as electrocatalysts for water‐splitting reactions. The introduced pristine MOFs are active electrocatalysts for oxygen evolution reaction. Common linkers with MOF synthesis methods are presented along with strategies to improve activities. Exploring other linkers and the catalytic role of individual metals are highlighted.
Advances in materials science have accelerated the development of diagnostic tools with the last decade witnessing the development of enzyme-free sensors, owing to the improved stability, low cost ...and simple fabrication of component materials. However, the specificity of non-enzymatic sensors for certain analytes still represents a challenging task, for example the determination of cholesterol level in blood is vital due to its medical relevance. In this work, a reagent displacement assay for cholesterol sensing in serum samples was developed. It is based on coating of a glassy carbon electrode with a polymer of intrinsic microporosity (PIM) that forms a host-guest complex with methylene blue (MB). In the presence of cholesterol, the MB electroactive probe was displaced due to the stronger association of cholesterol guest to the PIM host. The decrease in the oxidative current was proportional to the cholesterol concentration achieving a detection limit of approximately 0.1 nM. Moreover, to further assist the experimental studies, comprehensive theoretical calculations are also performed by using density functional theory (DFT) calculations.
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