In this work, we present an electrochemical sensor for fast, low-cost, and easy detection of the SARS-CoV-2 spike protein in infected patients. The sensor is based on a selected combination of ...nanomaterials with a specific purpose. A bioconjugate formed by Few-layer bismuthene nanosheets (FLB) and tetrahedral DNA nanostructures (TDNs) is immobilized on Carbon Screen-Printed Electrodes (CSPE). The TDNs contain on the top vertex an aptamer that specifically binds to the SARS-CoV-2 spike protein, and a thiol group at the three basal vertices to anchor to the FLB. The TDNs are also marked with a redox indicator, Azure A (AA), which allows the direct detection of SARS-CoV-2 spike protein through changes in the current intensity of its electrolysis before and after the biorecognition reaction. The developed sensor can detect SARS-CoV-2 spike protein with a detection limit of 1.74 fg mL−1 directly in nasopharyngeal swab human samples. Therefore, this study offers a new strategy for rapid virus detection since it is versatile enough for different viruses and pathogens.
2D materials show outstanding properties that can bring many applications in different technological fields. However, their uses are still limited by production methods. In this context, antimonene ...is recently suggested as a new 2D material to fabricate different (opto)electronic devices, among other potential applications. This work focuses on optimizing the synthetic parameters to produce high‐quality antimonene hexagons and their implementation in a large‐scale manufacturing procedure. By means of a continuous‐flow synthesis, few‐layer antimonene hexagons with ultra‐large lateral dimensions (up to several microns) and a few nanometers thick are isolated. The suitable chemical post‐treatment of these nanolayers with chloroform gives rise to antimonene surfaces showing low oxidation that can be easily contacted with microelectrodes. Therefore, the reported procedure offers a way to solve two critical problems for using antimonene in many applications: large‐scale preparation of high‐quality antimonene and the ability to set electrical contacts useful for device fabrication.
A continuous‐flow synthesis approach offers large‐scale preparation of high‐quality few‐layer antimonene (FLA) hexagons. This procedure is based on colloidal synthesis followed by a post‐treatment with chloroform to isolate FLA hexagons which present ultra‐large lateral dimensions and a few nanometers thickness. Mechanical and electrical analyses reveal their high‐quality and low surface oxidation, opening the door for applications in electronics and beyond.
A new quinoline-based COF (covalent organic framework), obtained by Povarov reaction, containing 2,6-diisopropylphenyl moieties as substituents over the heterocyclic ring is described for detecting ...Zn
in aqueous solution. The introduction of the mentioned bulky phenyl rings into the network favors an increase of the distance between the reticular sheets and their arrangement, obtaining a new material with an alternating AB type stacking. The new material exhibits good selectivity to detect Zn
by fluorescence emission in aqueous solutions up to a concentration of 1.2 × 10
m of the metal ion. In order to have a deeper insight into the interaction between the COF and the zinc cation, a thorough spectroscopical, microscopical, and theoretical study is also presented and discussed in this communication.
A novel porous and crystalline two-dimensional (2D) electrochemically active covalent organic framework (COF) based on orthoquinone units has been prepared as an innovative approach towards the ...development of organic cathode materials with multiple redox sites as an efficient electrocatalyst for the oxygen reduction reaction (ORR). In contrast with most of the previously reported COFs as electrocatalysts for the ORR, the electrocatalytic application of this material towards ORR has been investigated without adding any metal or conductive supporting material and avoiding any additional carbonization step. Additionally, the electrochemical properties of the COF material have been compared with two analogue amorphous frameworks with similar chemical composition, which points out the important role of the enhanced crystallinity and porosity of the COF network in its superior performance as an electrocatalyst towards ORR.
In this communication, a novel two-dimensional polymer network (DAPT-TFP) has been synthesized based on pyrenetetraone moieties connected through robust enamine functional groups. Results show that ...DAPT-TFP exhibit high thermal and chemical stability, even after subjecting the material to a basic or acidic media for certain time (1 M H2SO4 or 1 M NaOH, respectively). An application to conductive additive-free electrode is detailed, as a proof of the ideal interaction between the ions of the neutral aqueous electrolyte and the molecular polymer nanostructure activated by simple acidic treatment. Thus, the study indicates that the redox properties of new organic electrode materials exhibiting limited electroactive properties can be boosted by a straightforward acidic treatment.
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•A novel 2D polymer network was synthesized based on pyrenetetraone moieties linked by enamine groups.•The polymer shows reversible redox activity in neutral aqueous media after acidic activation without any conductive additives.•This strategy envies novel possibilities of developing materials by applying low-cost methods.
•High-quality few-layer bismuthene hexagons are prepared by solution phase synthesis under mild conditions.•The few-layer bismuthene hexagons present ultra-large areas and a few nanometers ...thicknesses.•The bismuth nanolayers present low oxidation surfaces and can be contacted with microelectrodes.•NADH sensor was fabricated where few-layers bismuthene act as electrocatalytic platforms.•The resulting sensor revealed high analytical performance in terms of sensitivity, selectivity, and reproducibility.
Many different two-dimensional (2D) materials have been reported and studied so-far showing outstanding physico-chemical properties that are expected to create many applications in various technological fields. However, the fabrication of many (opto)electronic devices and other components for different applications requires the availability of the material in large quantities. This work reports on a two-step procedure under mild conditions, preparing high-quality few-layer bismuthene (FLB) hexagons in good yield. The FLB hexagons so-formed show ultra-large lateral dimensions, over microns (ca. 2.75 to 4.5 µm), areas up to 30 µm2, while a few nanometers thick (5–20 nm). The chemical post-treatment of these nanolayers with chloroform produces bismuthene surfaces with very low oxidation that can be easily contacted with microelectrodes. FLB hexagons show high conductivity and excellent electrical properties, enabling them to fabricate an adenine dinucleotide (NADH) sensor where FLB hexagons act as electrocatalytic platforms with high capacity for improving the charge transfer process. The resulting sensor revealed high analytical performance in terms of sensitivity, selectivity, and reproducibility.
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AIM To evaluate the rate of adverse events(AEs) during consecutive gastric and duodenal polypectomies in several Spanish centers. METHODS Polypectomies of protruded gastric or duodenal polyps ≥ 5 mm ...using hot snare were prospectively included. Prophylactic measures of hemorrhage were allowed in predefined cases. AEs were defined and graded according to the lexicon recommended by the American Society for Gastrointestinal Endoscopy. Patients were followed for 48 h, one week and 1 mo after theprocedure. RESULTS308 patients were included and a single polypectomy was performed in 205. Only 36(11.7%) were on prior anticoagulant therapy. Mean polyp size was 15 ± 8.9 mm(5-60) and in 294 cases(95.4%) were located in the stomach. Hemorrhage prophylaxis was performed in 219(71.1%) patients. Nine patients presented AEs(2.9%), and 6 of them were bleeding(n = 6, 1.9%)(in 5 out of 6 AE, different types of endoscopic treatment were performed). Other 24 hemorrhagic episodes could be managed without any change in the outcome of the endoscopy and, consequently, were considered incidents. We did not find any independent risk factor of bleeding.CONCLUSION Gastroduodenal polypectomy using prophylactic measures has a rate of AEs small enough to consider this procedure a safe and effective method for polyp resection independently of the polyp size and location.
Phys. Rev. B 102, 024417 (2020) The interfacial Dzyaloshinskii-Moriya interaction (DMI) is of great interest
as it can stabilize chiral spin structures in thin films. Experiments verifying
the ...orientation of the interfacial DMI vector remain rare, in part due to the
difficulty of separating vector components of DMI. In this study, Fe/Ni
bilayers and Co/Ni multilayers were deposited epitaxially onto Cu(001) and
Pt(111) substrates, respectively. By tailoring the effective anisotropy, spin
reorientation transitions (SRTs) are employed to probe the orientation of the
DMI vector by measuring the spin structure of domain walls on both sides of the
SRTs. The interfacial DMI is found to be sufficiently strong to stabilize
chiral N\'eel walls in the out-of-plane magnetized regimes, while achiral
N\'eel walls are observed in the in-plane magnetized regimes. These findings
experimentally confirm that the out-of-plane component of the DMI vector is
insignificant in these fcc(001) and fcc(111) oriented interfaces, even in the
presence of atomic steps.
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