3R phase of MoS2 and WS2 outperforms the corresponding 2H phase for hydrogen evolution

Herein, we compare the bulk, 2H and 3R phases of two most prevalent TMD materials: MoS₂ and WS₂.

Transition metal (Mn, Fe, Co, Ni)-doped graphene hybrids for electrocatalysis

The development of electrocatalysts is crucial for renewable energy applications. Metal-doped graphene hybrid materials have been explored for this purpose, however, with much focus on noble metals, which are limited by their low availability and high costs. Transition metals may serve as promising alternatives. Here, transition metal-doped graphene hybrids were synthesized by a simple and scalable method. Metal-doped graphite oxide precursors were thermally exfoliated in either hydrogen or nitrogen atmosphere; by changing exfoliation atmospheres from inert to reductive, we produced materials with different degrees of oxidation. Effects of the presence of metal nanoparticles and exfoliation atmosphere on the morphology and electrocatalytic activity of the hybrid materials were investigated using electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry. Doping of graphene with transition metal nanoparticles of the 4th period significantly influenced the electrocatalysis of compounds important in energy production and storage applications, with hybrid materials exfoliated in nitrogen atmosphere displaying superior performance over those exfoliated in hydrogen atmosphere. Moreover, nickel-doped graphene hybrids displayed outstanding electrocatalytic activities towards reduction of O2 when compared to bare graphenes. These findings may be exploited in the research field of renewable energy.

Direct in vivo electrochemical detection of haemoglobin in red blood cells

The electrochemical behavior of iron ion in haemoglobin provides insight to the chemical activity in the red blood cell which is important in the field of hematology. Herein, the detection of haemoglobin in human red blood cells on glassy carbon electrode (GC) was demonstrated. Red blood cells or raw blood cells was immobilized on a glassy carbon electrode surface with Nafion films employed to sandwich the layer of biological sample firmly on the electrode surface. Cyclic voltammetry (CV) analyses revealed a well-defined reduction peak for haemoglobin at about -0.30 V (vs. Ag/AgCl) at the red blood cell (GC-Nf-RBC-3Nf) and blood (GC-Nf-B-3Nf) film modified GCE in a pH 3.5 phosphate buffer solution. We further demonstrated that the complex biological conditions of a human red blood cell displayed no interference with the detection of haemoglobin. Such findings shall have an implication on the possibilities of studying the electrochemical behaviour of haemoglobin directly from human blood, for various scientific and clinical purposes.

Iridium- and Osmium-decorated Reduced Graphenes as Promising Catalysts for Hydrogen Evolution

Renewable energy sources are highly sought after as a result of numerous worldwide problems concerning the environment and the shortage of energy. Currently, the focus in the field is on the development of catalysts that are able to provide water splitting catalysis and energy storage for the hydrogen evolution reaction (HER). While platinum is an excellent material for HER catalysis, it is costly and rare. In this work, we investigated the electrocatalytic abilities of various graphene-metal hybrids to replace platinum for the HER. The graphene materials were doped with 4f metals, namely, iridium, osmium, platinum and rhenium, as well as 3d metals, namely, cobalt, iron and manganese. We discovered that a few hybrids, in particular iridium- and osmium-doped graphenes, have the potential to become competent electrocatalysts owing to their low costs and-more importantly-to their promising electrochemical performances towards the HER. One of the more noteworthy observations of this work is the superiority of these two hybrids over MoS2 , a well-known electrocatalyst for the HER.

Bioavailability of metallic impurities in carbon nanotubes is greatly enhanced by ultrasonication

Metallic impurities within carbon nanotubes (CNTs) are considered as the main cause of their toxicity. Ultrasonication is a common procedure used to purify and obtain homogeneous dispersions of CNTs as well as to mix them with other components for further processing into composites. Herein, the influence of ultrasonication upon the bioavailability of metallic impurities in CNTs was investigated. We showed that even ultrasonication times as short as 5 min significantly enhanced the bioavailability of metallic impurities, which can therefore interact more actively with biologically important molecules. These findings will have profound impact on the processing of CNTs as well as on nanotoxicity studies.

Deposition of Aminomalononitrile-Based Films: Kinetics, Chemistry, and Morphology

In the last few years, the development of versatile coating chemistries has become a hot topic in surface science after the discovery that catecholamines can lead to conformal coatings upon oxidation from aqueous solutions. Recently, it was found that aminomalononitrile (AMN), a molecule implicated in the appearance of life on earth, is an excellent prototype of novel material-independent surface functionalizing agents leading to conformal and biocompatible coatings in a simple and direct chemical process from aqueous solutions. So far, very little insight has been gained regarding the mechanisms underlying coating deposition. In this paper, we show that the chemical evolution of AMN film deposition under slightly basic conditions is different in solution and on silica. Thereon, the coating proceeds via a nucleation process followed by further deposition of islands which evolve to produce nitrogen-rich superhydrophilic fibrillar structures. Additionally, we show that AMN-based material can form films at the air-solution interface from unshaken solutions. These results open new vistas into the chemistry of HCN-derived species of potential relevance in materials science.

Ultra-low fouling photocrosslinked coatings for the selective capture of cells expressing CD44

The effective control of biointerfacial interactions is of outstanding interest in a broad range of biomedical applications, ranging from cell culture tools to biosensors and implantable medical devices. For many of these applications, highly specific interactions between cells and material surfaces are desired. Sophisticated control over these interactions requires reducing or preventing non-specific interactions on the one hand and displaying highly specific signals that can be recognized by extracellular receptors on the other. We have recently developed ultra-low fouling coatings that can be applied in a single step using photoreactive copolymers of 2-hydroxypropyl acrylamide and N-benzophenone acrylamide. Here, we have expanded this approach by incorporating polymerizable peptide monomers into these copolymers. The monomers QQGWFGAGK(acrylamide) and acrylamide-GAGQQGWF were synthesized after identifying the QQGWF sequence as a binding motif for CD44 by phage display for the first time. Our results demonstrate that UV-crosslinked coatings fabricated using the QQGWFGAGK(acrylamide) monomer are effective at selectively binding hMSC in the presence of HepG2 and HEK293 cells due to the difference in CD44 expression. Our results also demonstrate that the peptide modified coatings retain their low biofouling character using a BCA protein binding assay as well as an E. coli bacterial attachment assay over a 24 h period. Our approach provides an alternative to traditional integrin-mediated selective cell binding on surfaces and opens the door to new diagnostic applications, exploiting the fact that the transmembrane protein CD44 is highly expressed in multiple diseases.

Evolution and stability of 2-mercaptobenzimidazole inhibitor film upon Al alloy 6061

Organic corrosion inhibitors have become competent alternatives to hazardous chrome conversion coatings due to their rapid adsorption over metal surfaces in corrosive environments. Literature suggests a wide range of organic corrosion inhibitors with high inhibition efficiency, barrier properties, and adsorption mechanisms. However, the long-term durability and protectiveness of an organic inhibitor film need to be understood with in-depth insights on its interaction with heterogenous alloy surfaces like AA6xxx, reduction of galvanic activities and time-resolved degradation due to ionic diffusion. The present article is focused on the time-resolved adsorption and degradation of 2-mercaptobenzimidazole (2-MBI)-induced inhibitor layer/film over AA6061 in 0.1 M NaCl solution. Electrochemical and surface analysis data indicate that the presence of 2-MBI drives the rapid formation of a 20–30 nm thick protective film comprised of constitutional elements of C, S, and N from 2-MBI upon the surface of AA6061 substrate. This film mitigated the corrosion cells associated with nano- and micro-sized Fe and Si-rich intermetallic particles (IMPs) in AA6061. XPS reveals two distinguished bonding states of S and N in the inhibitor film and chemical interactions between 2-MBI and the surface of AA6061. The protective film maintained 65% inhibiting efficiency after 1 day, which progressively degraded due to electrolyte ingress and eventually with a drop in inhibition efficiency down to 21% after 14 days. Inhibitor-induced film over AA6061 reduced the corrosion susceptibility of Fe, and Si-rich IMPs up to 1 day given the subsequent adsorption by S and N heteroatoms. However, this film became thick and defective after 1 day, which undermined its barrier properties against ingress of aggressive ions and facilitated water adsorption.

Graphical abstract

Cholesterol uptake capacity: a new measure of HDL functionality as a predictor of subsequent revascularization in patients undergoing percutaneous coronary intervention

Background

Recent studies have demonstrated the importance of high-density lipoprotein (HDL) functionality in the development of de novo coronary artery disease by using the cholesterol-efflux capacity, a measure of the ability of HDL to promote cholesterol removal from lipid-laden macrophages. Recently, we developed a rapid cell-free assay system to directly evaluate the capacity of HDL to accept additional cholesterol; the measurement of the cholesterol-uptake capacity (CUC) enables HDL functionality to be readily evaluated in our daily practice. However, prognostic implication of CUC measurement at the timing of percutaneous coronary intervention (PCI) remains unclear.

Purpose

We aimed to evaluate the association between baseline CUC and revascularization during follow-up in the patients who underwent PCI.

Methods

We retrospectively reviewed the patients who underwent PCI with follow-up coronary angiography (CAG) or ischemic-driven revascularization. The patients who had the frozen blood samples of which CUC were measurable at the index PCI and follow-up CAG or revascularization were enrolled. We excluded the patients under hemodialysis.

Results

Among a total of 703 consecutive patients who underwent PCI between Dec 2014 and Mar 2019, we finally enrolled 74 patients who underwent ischemic-driven revascularization (revascularization group) and 183 patients who underwent follow-up CAG without revascularization (non-revascularization group).There were no significant difference in baseline traditional cardiovascular risk factors between the groups. However, the presence of diabetes was significantly more frequent in the revascularization group (63.5% vs 41.0%; P=0.001) than in the non-revascularization group. CUC at the index PCI was significantly lower in the revascularization group than in the non-revascularization group (87.0±19.5 vs 93.9±19.2; P=0.004). Multivariate logistic regression analysis revealed that impaired HDL functionality assessed by decreased CUC level at the index PCI (odds ratio; 0.984, 95% confidence interval; 0.969–1.000) was independently associated with subsequent revascularization after PCI. Indeed, there was a graded inverse association between increasing tertiles of CUC levels and the incidence of revascularization during a median follow-up of 881 days (Figure). Especially in the subgroup analysis of non-diabetic patients, decreased CUC level at the index PCI was independently associated with subsequent revascularization (odds ratio; 0.947, 95% confidence interval; 0.915–0.981), while not in diabetic population.

Conclusion

Serum CUC level at the index procedure was associated with subsequent revascularization especially in non-diabetic patients who underwent PCI.

Funding Acknowledgement

Type of funding source: None