scholarly journals Copper(I)-Catalyzed Click Chemistry as a Tool for the Functionalization of Nanomaterials and the Preparation of Electrochemical (Bio)Sensors

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2379 ◽  
Author(s):  
P. Yáñez-Sedeño ◽  
A. González-Cortés ◽  
S. Campuzano ◽  
J. M. Pingarrón
Keyword(s):  
Electrochemical Sensors ◽  
Functional Integration ◽  
Future Directions ◽  
Physiological Conditions ◽  
Electrode Surfaces ◽  
Wide Range ◽  
High Yields ◽  
By Products ◽  
Powerful Strategy

Proper functionalization of electrode surfaces and/or nanomaterials plays a crucial role in the preparation of electrochemical (bio)sensors and their resulting performance. In this context, copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been demonstrated to be a powerful strategy due to the high yields achieved, absence of by-products and moderate conditions required both in aqueous medium and under physiological conditions. This particular chemistry offers great potential to functionalize a wide variety of electrode surfaces, nanomaterials, metallophthalocyanines (MPcs) and polymers, thus providing electrochemical platforms with improved electrocatalytic ability and allowing the stable, reproducible and functional integration of a wide range of nanomaterials and/or different biomolecules (enzymes, antibodies, nucleic acids and peptides). Considering the rapid progress in the field, and the potential of this technology, this review paper outlines the unique features imparted by this particular reaction in the development of electrochemical sensors through the discussion of representative examples of the methods mainly reported over the last five years. Special attention has been paid to electrochemical (bio)sensors prepared using nanomaterials and applied to the determination of relevant analytes at different molecular levels. Current challenges and future directions in this field are also briefly pointed out.

scholarly journals Dispersive evaluation and surface chemistry of advanced, multifunctional silica/lignin hybrid biomaterials

2013 ◽  
Vol 11 (11) ◽  
pp. 1860-1873 ◽  
Author(s):  
Magdalena Nowacka ◽  
Łukasz Klapiszewski ◽  
Małgorzata Norman ◽  
Teofil Jesionowski
Keyword(s):  
Zeta Potential ◽  
Surface Charge ◽  
Electrochemical Sensors ◽  
Relevant Information ◽  
Structural Features ◽  
Kraft Lignin ◽  
Morphological Properties ◽  
Wide Range ◽  
Hybrid Biomaterials

AbstractAdvanced silica/lignin hybrid biomaterials were obtained using hydrated or fumed silicas (Aerosil®200) and Kraft lignin as precursors, which is a cheap and biodegradable natural polymer. To extend the possible range of applications, the silicas were first modified with N-2-(aminoethyl)-3-aminopropyltrimethoxsysilane, and then with Kraft lignin, which had been oxidized with sodium periodate. The SiO2/lignin hybrids and precursors were characterised by means of determination of their physicochemical and dispersive-morphological properties. The effectiveness of silica binding to lignin was verified by FT-IR spectroscopy. The zeta potential value provides relevant information regarding interactions between colloid particles. Measurement of the zeta potential values enabled an indirect assessment of stability for the studied hybrid systems. Determination of zeta potential and density of surface charge also permitted the quantitative analysis of changes in surface charge, and indirectly confirmed the effectiveness of the proposed method for synthesis of SiO2/lignin hybrid materials. A particularly attractive feature for practical use is their stability, especially electrokinetic stability. It is expected that silica/lignin hybrids will find a wide range of applications (polymer fillers, biosorbents, electrochemical sensors), as they combine the unique properties of silica with the specific structural features of lignin. This makes these hybrids biomaterials advanced and multifunctional.

scholarly journals A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed-bed microreactor

2009 ◽  
Vol 5 ◽  
Author(s):  
Andrew Bogdan ◽  
D Tyler McQuade
Keyword(s):  
Packed Bed ◽  
Secondary Alcohols ◽  
Great Stability ◽  
Wide Range ◽  
Oxidation Of Alcohols ◽  
Aldehydes And Ketones ◽  
High Yields ◽  
By Products ◽  
Over Time

We demonstrate the preparation and characterization of a simplified packed-bed microreactor using an immobilized TEMPO catalyst shown to oxidize primary and secondary alcohols via the biphasic Anelli-Montanari protocol. Oxidations occurred in high yields with great stability over time. We observed that plugs of aqueous oxidant and organic alcohol entered the reactor as plugs but merged into an emulsion on the packed-bed. The emulsion coalesced into larger plugs upon exiting the reactor, leaving the organic product separate from the aqueous by-products. Furthermore, the microreactor oxidized a wide range of alcohols and remained active in excess of 100 trials without showing any loss of catalytic activity.

Electrochemical Sensors Based on Noble Metal Nanoparticles in Voltammetry

2021 ◽  
Vol 887 ◽  
pp. 54-59
Author(s):  
D.O. Perevezentseva ◽  
Eduard V. Gorchakov
Keyword(s):  
Metal Nanoparticles ◽  
Noble Metal ◽  
Electrochemical Sensors ◽  
Narrow Range ◽  
Spherical Shape ◽  
High Sensitivity ◽  
Noble Metal Nanoparticles ◽  
Wide Range ◽  
Sulfur Containing

Portable electrochemical sensors based on noble metal nanoparticles (МеNPs) for the quantitative determination of hydrogen peroxide (H2O2) and sulfur-containing amino acids (cysteine, methionine, glutathione) are discussed. These sensors have high sensitivity (pM), with low sample requirements (<50 μl). This article discusses methods for producing sensors based on silver and gold nanoparticles and their application in voltammetry. It is shown that the sensitivity of H2O2 determination on a sensor based on silver nanoparticles (AgNPs) depends on their size. Their size is determined by the reducing agent. Sensors based on AgNPs of spherical shape with the smallest size from 0.5 to 17.5 nm have the highest sensitivity for determining H2O2, but a narrow range of determined concentrations. Sensors on medium-sized AgNPs have optimal metrological characteristics. Their size is from 10 to 55 nm, less sensitive, but with a wide range of determined concentrations from 0.1 to 1 nm H2O2. The linearity of the range of glutathione concentrations is 1.0-10.0 pM. The linearity of the range of determined concentrations of methionine is 1–26 рМ.

scholarly journals DNA Nanodevices as Mechanical Probes of Protein Structure and Function

2021 ◽  
Vol 11 (6) ◽  
pp. 2802
Author(s):  
Nicholas Stephanopoulos ◽  
Petr Šulc
Keyword(s):  
Protein Structure ◽  
Protein Function ◽  
Cell Activation ◽  
Dna Nanotechnology ◽  
Future Directions ◽  
Precise Control ◽  
Wide Range ◽  
Promising Application ◽  
And Function

DNA nanotechnology has reported a wide range of structurally tunable scaffolds with precise control over their size, shape and mechanical properties. One promising application of these nanodevices is as probes for protein function or determination of protein structure. In this perspective we cover several recent examples in this field, including determining the effect of ligand spacing and multivalency on cell activation, applying forces at the nanoscale, and helping to solve protein structure by cryo-EM. We also highlight some future directions in the chemistry necessary for integrating proteins with DNA nanoscaffolds, as well as opportunities for computational modeling of hybrid protein-DNA nanomaterials.

scholarly journals Disinfection by-products monitoring in water of selected outdoor swimming pools in Opole Voivodship

2018 ◽  
Vol 59 ◽  
pp. 00027
Author(s):  
Iwona Klosok-Bazan ◽  
Marta Bożym ◽  
Małgorzata Wzorek
Keyword(s):  
Swimming Pool ◽  
Swimming Pools ◽  
Wide Range ◽  
By Products

The aim of this study was to determine the level of disinfection by-products in selected outdoor swimming pool in the Opole Voivodship. The authors paid special attention to the determination of the concentration of trihalomethanes (THMs), which are formed during disinfection in water. Five outdoor swimming pools were selected in five different cities located in Opole Region. The level of trihalomethane (THM) concentrations in the analyzed waters was found to be in the wide range from 15 to more than 550 µg/L. The dominant compound of THMs was chloroform because of chlorine application in the disinfection method.

History of the Study of Apocrypha in Early Medieval England

2020 ◽  
Vol 48 (3-4) ◽  
pp. 13-26
Author(s):  
Brandon W. Hawk
Keyword(s):  
Old Testament ◽  
Medieval England ◽  
Medieval Period ◽  
Early Medieval ◽  
Future Directions ◽  
Early Judaism ◽  
Wide Range ◽  
History Of ◽  
The Subject ◽  
Early English

Literature written in England between about 500 and 1100 CE attests to a wide range of traditions, although it is clear that Christian sources were the most influential. Biblical apocrypha feature prominently across this corpus of literature, as early English authors clearly relied on a range of extra-biblical texts and traditions related to works under the umbrella of what have been called “Old Testament Pseudepigrapha” and “New Testament/Christian Apocrypha." While scholars of pseudepigrapha and apocrypha have long trained their eyes upon literature from the first few centuries of early Judaism and early Christianity, the medieval period has much to offer. This article presents a survey of significant developments and key threads in the history of scholarship on apocrypha in early medieval England. My purpose is not to offer a comprehensive bibliography, but to highlight major studies that have focused on the transmission of specific apocrypha, contributed to knowledge about medieval uses of apocrypha, and shaped the field from the nineteenth century up to the present. Bringing together major publications on the subject presents a striking picture of the state of the field as well as future directions.

Stereospecific, Palladium-catalyzed C(sp3)–H Alkenylation and Alkynylation of a Proline Derivative Enabled by 8-Aminoquinoline as a Directing Group

2020 ◽  
Author(s):  
Aleksandra Balliu ◽  
Aaltje Roelofje Femmigje Strijker ◽  
Michael Oschmann ◽  
Monireh Pourghasemi Lati ◽  
Oscar Verho
Keyword(s):  
Carboxylic Acid ◽  
Building Blocks ◽  
Wide Range ◽  
Palladium Catalyzed ◽  
Directing Group ◽  
High Yields ◽  
Vinyl Iodides ◽  
Initial Results

<p>In this preprint, we present our initial results concerning a stereospecific Pd-catalyzed protocol for the C3 alkenylation and alkynylation of a proline derivative carrying the well utilized 8‑aminoquinoline directing group. Efficient C–H alkenylation was achieved with a wide range of vinyl iodides bearing different aliphatic, aromatic and heteroaromatic substituents, to furnish the corresponding C3 alkenylated products in good to high yields. In addition, we were able show that this protocol can also be used to install an alkynyl group into the pyrrolidine scaffold, when a TIPS-protected alkynyl bromide was used as the reaction partner. Furthermore, two different methods for the removal of the 8-aminoquinoline auxiliary are reported, which can enable access to both <i>cis</i>- and <i>trans</i>-configured carboxylic acid building blocks from the C–H alkenylation products.</p>

Synthetic and Mechanistic Studies of a Versatile Heteroaryl Thioether Directing Group for Pd(II) Catalysis

2019 ◽  
Author(s):  
Andrew Romine ◽  
Kin Yang ◽  
Malkanthi Karunananda ◽  
Jason Chen ◽  
Keary Engle
Keyword(s):  
Mechanistic Studies ◽  
Salvianolic Acid ◽  
Wide Range ◽  
Computational Data ◽  
Synthetic Utility ◽  
Directing Group ◽  
High Yields ◽  
Julia Olefination ◽  
Reaction Progress Kinetic Analysis

A weakly coordinating monodentate heteroaryl thioether directing group has been developed for use in Pd(II) catalysis to orchestrate key elementary steps in the catalytic cycle that require conformational flexibility in a manner that is difficult to accomplish with traditional strongly coordinating directing groups. This benzothiazole thioether, (BT)S, directing group can be used to promote oxidative Heck reactivity of internal alkenes providing a wide range of products in moderate to high yields. To demonstrate the broad applicability of this directing group, arene C–H olefination was also successfully developed. Reaction progress kinetic analysis provides insights into the role of the directing group in each reaction, which is supplemented with computational data for the oxidative Heck reaction. Furthermore, this (BT)S directing group can be transformed into a number of synthetically useful functional groups, including a sulfone for Julia olefination, allowing it to serve as a “masked olefin” directing group in synthetic planning. In order to demonstrate this synthetic utility, natural products (+)-salvianolic acid A and salvianolic acid F are formally synthesized using the (BT)S directed C–H olefination as the key step.

A review on aversive Pavlovian-to-Instrumental transfer in humans

2020 ◽  
Author(s):  
Anna Gerlicher ◽  
Merel Kindt
Keyword(s):  
Avoidance Behavior ◽  
Neural Circuits ◽  
Transfer Effects ◽  
Future Directions ◽  
Transfer Paradigm ◽  
Wide Range ◽  
Threat Cues ◽  
Imminent Threat ◽  
Fear And Anxiety ◽  
Pathological Anxiety

A cue that indicates imminent threat elicits a wide range of physiological, hormonal, autonomic, cognitive, and emotional fear responses in humans and facilitates threat-specific avoidance behavior. The occurrence of a threat cue can, however, also have general motivational effects and affect behavior. That is, the encounter with a threat cue can increase our tendency to engage in general avoidance behavior that does neither terminate nor prevent the threat-cue or the threat itself. Furthermore, the encounter with a threat-cue can substantially reduce our likelihood to engage in behavior that leads to rewarding outcomes. Such general motivational effects of threat-cues on behavior can be informative about the transition from normal to pathological anxiety and could also explain the development of comorbid disorders, such as depression and substance abuse. Despite the unmistakable relevance of the motivational effects of threat for our understanding of anxiety disorders, their investigation is still in its infancy. Pavlovian-to-Instrumental transfer is one paradigm that allows us to investigate such motivational effects of threat cues. Here, we review studies investigating aversive transfer in humans and discuss recent results on the neural circuits mediating Pavlovian-to-Instrumental transfer effects. Finally, we discuss potential limitations of the transfer paradigm and future directions for employing Pavlovian-to-Instrumental transfer for the investigation of motivational effects of fear and anxiety.

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