MoS2 flakes stabilized with DNA/RNA nucleotides: in vitro cell response

Two-dimensional transition metal dichalcogenides (TMDCs), such as MoS2 and WS2, have recently emerged as nanomaterials with potential use in biomedicine. An attractive means to favor their interaction with biological media is the use of proper biomolecules as exfoliating/dispersing agents. Here, MoS2 flakes were stabilized with different small functional biomolecules such as adenosine monophosphate (AMP), guanosine monophosphate (GMP) and flavin mononucleotide (FMN) through the strong nucleotide-MoS2 interaction of Lewis acid-base type, rather than just on the weak dispersive and hydrophobic forces commonly associated with the use of many surfactants. The impact of the nucleotide-stabilized MoS2 flakes on the viability and cell proliferation, on the production of intracellular reactive oxygen species (ROS), and on the preosteoblast differentiation process (early stage) has been also evaluated, as well as the incorporation and intracellular localization of the nanomaterials by MC3T3-E1 and Saos-2 cells. The nucleotide-stabilized MoS2 flakes were found to exhibit excellent biocompatibility. Furthermore, their incorporation did not affect the integrity of the cell plasma membrane, which makes them ideal candidates for delivering drug/gene directly into cells. The in vitro cell response of tumor cells to these nanomaterials differs from that of undifferentiated cells, which provides the basis for their potential use in cancer therapy.publishe

Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.

BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden

Nitrogen in aramid-based activated carbon fibers by TPD, XPS and XANES

International audienceActivated carbon fibers were prepared from Nomex@ [poly(m-phenylene isophthalamide)] by either H3PO4 activation, H3PO4–CO2 activation, or simply CO2 or steam activation. These treatments converted amide groups from the polymer precursor into complex and heterogeneously distributed nitrogen functionalities. TPD, XPS and XANES were used to study the effects of these treatments on the local bonding environment around nitrogen in the resulting carbons. These analytical techniques showed that nitrogen atoms are present in the 6-membered rings located at the edges of condensed polyaromatic systems as pyridine-like sp2 nitrogen (N1 or N2) or in the inte¬rior, where nitrogen replaces one carbon atom and is bonded to three carbon neighbors (N3). The occurrence of a species (N2) hypo¬thetically related to a pyridinic cycle bearing oxygen substituents or intracyclic oxygen atoms could be correlated with the degree of oxidation of the carbon surface. Assuming that a relative N3 increase is indicative of aromatization and that the reverse, correlated with a N2 increase, is indicative of surface oxidative denitrogenation, the ratio between these nitrogen species revealed that aromatization and oxidative denitrogenation processes occur sequentially or simultaneously to different extents according to the type of carbon activation and to the burn-off degree. Physical activation involves thermal aromatization reactions during the carbonization stage and the subse¬quent isothermal activation one. In this second activation stage, co-occurring thermal oxidation reactions lead to a less intense denitro¬genation during CO2 activation than during steam activation. H3PO4 activation induces the largest nitrogen retention in the final product in a double process of aromatization and ‘‘auto-activation'' producing a moderate oxidative attack of nitrogen. However, an increase of the H3PO4 ratio fostered the oxidation of the carbon surface and consequently enhanced nitrogen gasification during the subsequent activation

Biomimetic nucleotide-graphene hybrids for electrocatalytic oxygen conversion: quantifying biomolecule mass loading

Metal-free electrocatalysts for the electrochemical conversion of gases constitute an important asset for a sustainable energy transition. Nucleotides act as redox mediators in the electron transport chain to reduce oxygen in cellular respiration. The biomimicry of such an efficient natural mechanism could be utilized to address the challenges associated with electrochemical gas conversion technologies, such as sluggish kinetics and high overpotentials. Multiple descriptors are generally reported to benchmark the activity of electrocatalysts where the turnover frequency (TOF) is claimed to be the most accurate criterion. Here, a library of graphene nanosheets-nucleotide hybrid materials was prepared, and the electrocatalytic performance towards ORR/OER reactions of a graphene-flavin mononucleotide hybrid was evaluated by rotating disc electrode experiments and TOF estimation. The determination of catalyst loading and dispersion is especially relevant when assessing the intrinsic activity of a catalyst and, therefore, the amount of nucleotide electrocatalyst loaded into the graphene support was thoroughly quantified by a combination of characterization techniques. Density functional theory calculations supported the observed experimental trends, both on the adsorption rate of a given nucleotide on graphene and the catalytic activity of a specific hybrid material. This work constitutes an avenue to predict nature-mimicking electrocatalysts for efficient energy storage