Hasil untuk "Organic chemistry"

Xianjun Lang, Xiaodong Chen, Jincai Zhao

D. O'Hagan

Björn D. Lindahl, A. Tunlid

Stuart L. James

B. Honig, A. Nicholls

R. Atkinson

James W. B. Fyfe, A. Watson

Houman Kholafazad, Mahdiyeh Pazhuhi, Mohammad Hasanzadeh et al.

Microneedles (MNs) have emerged as a cutting-edge sensing approach due to their enhanced surface area, improved sample penetration, localized detection, and potential for enhanced sensitivity. However, some MN manufacturing methods involve complex procedures, costly equipment, and non-biocompatible materials. Additionally, challenges in integrating MNs into existing technologies hinders their application in rapid and low-cost sensor technology. This study reports the development of innovative MNs fabricated using readily available cellulosic-based paper fibers, in which fibers from Whatman paper mixed with 1 % polyvinyl alcohol (PVA) were shaped using a polydimethylsiloxane (PDMS) mold. The MNs operate based on both physical penetration force and fluidic absorption via capillary action in the porous cellulosic matrix. The MNs exhibit low reagent and sample volume requirements along with flexibility and ease of penetration into samples, and filtration capabilities that allow efficient detection with minimal interference. The structure of MNs was investigated by field emission scanning electron microscopy (FE-SEM), revealing a conical shape with an average height of ∼750 µm and a diameter of ∼500 µm. The performance of the MN sensors was validated by colorimetric detection of heavy metals in fish, demonstrating linear ranges of 0.6 to 8 mg/L, 0.2 to 4 mg/L, and 0.3 to 6 mg/L for copper Cu(II), chromium Cr(VI), and nickel Ni(II), respectively. The colorimetric detection, combined with smartphone-based digital image analysis, exhibited lower limit of quantification (LLOQ) of 0.6, 0.2, and 0.3 mg/L for Cu(II), Cr(VI), and Ni(II), respectively, with no significant interference in the presence of potential interfering ions.

Sun Sishuai, Gu Lingui, Li Pengtao et al.

Abstract Endothelial-mesenchymal transformation (EndoMT) is the process through which endothelial cells transform into mesenchymal cells, affecting their morphology, gene expression, and function. EndoMT is a potential risk factor for cardiovascular and cerebrovascular diseases, tumor metastasis, and fibrosis. Recent research has highlighted the role of exosomes, a mode of cellular communication, in the regulation of EndoMT. Exosomes from diseased tissues and microenvironments can promote EndoMT, increase endothelial permeability, and compromise the vascular barrier. Conversely, exosomes derived from stem cells or progenitor cells can inhibit the EndoMT process and preserve endothelial function. By modifying exosome membranes or contents, we can harness the advantages of exosomes as carriers, enhancing their targeting and ability to inhibit EndoMT. This review aims to systematically summarize the regulation of EndoMT by exosomes in different disease contexts and provide effective strategies for exosome-based EndoMT intervention.

J. Orlando, G. Tyndall

R. Alan Aitken, Lynn A. Power, Alexandra M. Z. Slawin

(2<i>S</i>,5<i>S</i>)-5-Phenyl-2-<i>t</i>-butyl-1,3-dioxolan-4-one, readily derived from mandelic acid, undergoes the Michael addition to butenolide and 4-methoxy-β-nitrostyrene with the absolute configuration of the products confirmed by X-ray diffraction in each case. In the former case, thermal fragmentation gives the phenyl ketone, thus illustrating use of the dioxolanone as a chiral benzoyl anion equivalent. The Diels–Alder cycloaddition chemistry of (2<i>S</i>)-5-methylene-2-<i>t</i>-butyl-1,3-dioxolan-4-one, derived from lactic acid, has been further examined with the X-ray structures of four adducts determined. In one case, thermal fragmentation of the adduct gives a chiral epoxy ketone resulting from the dioxolanone acting as a chiral ketene equivalent, while in others the products give insight into the mechanism of the dioxolanone fragmentation process.

Denise Soares, Joana Lourenço, Ana Filipa Silva et al.

PURPOSE Shot-put is a complex ballistic movement that involves segments’ translational and rotational motions. Its goal is to release the shot at maximum forward velocity (strength) at an angle of approximately 40º (rotation). Considering the adapted shot-put, those two components could be more limited in action. Therefore, the present study aimed to examine the correlations among the one-repe-tition maximum (1RM) test in the bench press (BP1RM) and trunk rotation (TR1RM) and the throwing distance of the adapted shot-put and body composition (Fat mass and Fat-free mass [FFM]), and the throwing distance of the adapted shot-put (TD) and 1RM results. METHODS Eighteen non-professional athletes were evaluated, and their anthropometric data were obtained (bio-impedance measurements). Afterward, the participants performed the BP1RM and TR1RM exercises. Finally, they performed the adapted shot-put in similar conditions as the official competitions, where three trials of ASP were performed, and the best of these trials were assessed. RESULTS The results showed a significant relationship between the throwing distance and 1RM results for both exercises (BP1RM (p=.040) and TR1RM (p=.002)) and with the amount of FFM (p=.045). Concerning FFM relationships, the results showed a positive relationship with both 1RM exercises (BP1RM (p=.034) and TR1RM (p=.003)). The Fat Mass results demonstrated an inverse correlation only with BP1RM (p=.035). CONCLUSIONS The results suggest that physical preparation, including BP1RM and TR1RM exercises, are fundamental to improving adapted shot-put performance. This showed preliminary indicators of which variables may influence the adapted shot-put that might help coaches and athletes to improve their performance. Nevertheless, those results should be carefully considered since the movement evaluated was very complex, especially when performed by participants unfamiliar with them, and because the same analysis included both sexes.

Raúl M. Pérez-García, Patrick J. Riss, Patrick J. Riss et al.

A tris(pentafluorophenyl)borane catalysed method for the synthesis of boronic acid esters from aromatic amines in yields of up to 93% was devised. Mild conditions, benign reagents, short reaction times, low temperatures and a wide substrate scope characterize the method. The reaction was found applicable to the synthesis of boronic acid ester derivatives of complex drug molecules in up to 86% isolated yield and high purity suitable for labelling. These boronates were subsequently labelled with [18F]fluoride ion in radiochemical yields of up to 55% with and even without isolation of the boronate-intermediate.

Funda OZKOK, Mehmet BOĞA, Muhammed TUNEG et al.

In this study, the enzyme activity of anthraquinone compounds which were synthesized beforehand by our research group was investigated. Molecular docking studies were performed for compounds 1-(4-aminophenylthio)anthracene-9,10-dione (3) and 1-(4-chlorophenylthio)anthracene-9,10-dione (5). Compound 3 was synthesized from the reaction of 1-chloroanthraquinone (1) and 4-aminothiophenol (2). Compound 5 was synthesized (1) from the reaction of 1-chloroanthraquinone (1) and 4-chlorothiophenol (4). Anthraquinone analogs (3, 5) were synthesized with a new reaction method made by our research group (2). Inhibitory effects of compounds 3 and 5 were investigated against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes which are related to Alzheimer’s Disease (AD). Compounds 3 and 5 exhibited strong anti-acetyl- and butyryl-cholinesterase inhibition activities than galanthamine used as standard compound (92.11±1.08 and 80.95±1.77 %, respectively). The EHOMO-ELUMO values, molecular descriptors, and the calculated UV-Vis spectra of anthraquinone derivatives were computed by B3LYP/6-31+G(d,p) levels in the CHCl3 phase. Based on the fluorescence property of the anthraquinone skeleton, the fluorescence activity of the bioactive anthraquinone analogue (5) was investigated. MTT test was performed to determine the cytotoxic effects of thioanthraquinone molecules 3 and 5. In MTT analyses, 3 compounds showed the highest effect against Ishikawa cells at a dose of 10 µg/mL, while compound 5 showed the highest effect at a dose of 50 µg/mL. The cell viability for compound 3 was 84.18% for 10 µg/mL and the cell viability for compound 5 was 75.02% for 50 µg/mL.

Mubashir Aziz, Syeda Abida Ejaz, Nissren Tamam et al.

Abstract NIMA related Kinases (NEK7) plays an important role in spindle assembly and mitotic division of the cell. Over expression of NEK7 leads to the progression of different cancers and associated malignancies. It is becoming the next wave of targets for the development of selective and potent anti-cancerous agents. The current study is the first comprehensive computational approach to identify potent inhibitors of NEK7 protein. For this purpose, previously identified anti-inflammatory compound i.e., Phenylcarbamoylpiperidine-1,2,4-triazole amide derivatives by our own group were selected for their anti-cancer potential via detailed Computational studies. Initially, the density functional theory (DFT) calculations were carried out using Gaussian 09 software which provided information about the compounds' stability and reactivity. Furthermore, Autodock suite and Molecular Operating Environment (MOE) software’s were used to dock the ligand database into the active pocket of the NEK7 protein. Both software performances were compared in terms of sampling power and scoring power. During the analysis, Autodock results were found to be more reproducible, implying that this software outperforms the MOE. The majority of the compounds, including M7, and M12 showed excellent binding energies and formed stable protein–ligand complexes with docking scores of − 29.66 kJ/mol and − 31.38 kJ/mol, respectively. The results were validated by molecular dynamics simulation studies where the stability and conformational transformation of the best protein–ligand complex were justified on the basis of RMSD and RMSF trajectory analysis. The drug likeness properties and toxicity profile of all compounds were determined by ADMETlab 2.0. Furthermore, the anticancer potential of the potent compounds were confirmed by cell viability (MTT) assay. This study suggested that selected compounds can be further investigated at molecular level and evaluated for cancer treatment and associated malignancies.

Shuang Chen, Meng Hu, Lingyu Liu et al.

Summary: Carbon is one of the most versatile atoms and fosters a wealth of carbon allotropes with superior mechanical and electronic properties. A three-dimensional covalent carbon nanotube, named CCN, with a hexagonal honeycomb-like crystalline structure is proposed theoretically. CCN consists of sp3 bonded coaxially teamed (6,0) carbon nanotubes, and the tube walls possess intrinsic wrinkles, which trigger miraculous physical properties. The mechanical and thermal dynamic stabilities are confirmed, and molecular dynamics simulations indicate high temperature thermal stability up to 1500 K. CCN has an unusual cork-like zero Poisson’s ratio along the axial direction of the nanotubes, and the axial/radial stretching or compression rarely effects the radial/axial dimensions of the nanotubes. CCN is superhard with Vickers hardness of 82.8 GPa, matching that of cubic boron nitride. Substitution B and N atoms for C atoms result in superhard CCN-B12N8 and CCN-C8N12 with quasi-zero Poisson’s radio along both axial and radial directions.

Javier Casas, Jesús Balsinde, María A. Balboa

Group IVA cytosolic phospholipase A₂α (cPLA₂α) is a key enzyme in physiology and pathophysiology because it constitutes a rate-limiting step in the pathway for the generation of pro- and anti-inflammatory eicosanoid lipid mediators. cPLA₂α activity is tightly regulated by multiple factors, including the intracellular Ca²⁺ concentration, phosphorylation reactions, and cellular phosphatidylinositol (4,5) bisphosphate levels (PtdInsP₂). In the present work, we demonstrate that phosphorylation of the enzyme at Ser⁵⁰⁵ is an important step for the translocation of the enzyme to PtdInsP₂–enriched membranes in human cells. Constructs of eGFP-cPLA₂ mutated in Ser⁵⁰⁵ to Ala (S505A) exhibit a delayed translocation in response to elevated intracellular Ca²⁺, and also in response to increases in intracellular PtdInsP₂ levels. Conversely, translocation of a phosphorylation mimic mutant (S505E) is fully observed in response to cellular increases in PtdInsP₂ levels. Collectively, these results suggest that phosphorylation of cPLA₂α at Ser⁵⁰⁵ is necessary for the enzyme to translocate to internal membranes and mobilize arachidonic acid for eicosanoid synthesis.

Rajasekhar Reddy Naredla, D. Klumpp

Daniel J. Burke, D. Lipomi

Essentially all methods of energy production—e.g., fracking, damming, drilling, nuclear fission, and excavation of rare elements for photovoltaics—are associated with some degree of environmental degradation. Organic solar cells (OSCs) are regarded as low-cost and potentially environmentally benign sources of power. π-Conjugated (semiconducting) polymers—the components of OSCs responsible for absorbing light and transporting charge—are not typically synthesized in laboratories in ways that are amenable to manufacturing with low environmental impact. This article discusses strategies for producing conjugated polymers using green chemistry. That is, reaction methodology with low energy intensity, with minimal production of toxic waste, and at low cost. This article briefly reviews the major findings in the literature on the energy intensity and carbon emissions associated with fabricating OSCs on the laboratory scale, and identifies several strategies and materials invented by the community to lower the cost and environmental impact of the components of the devices. The principles of green chemistry, applied to the synthesis of conjugated polymers, are identified as important guidelines for the multi-tonne manufacturing of these materials. A general theme in both green chemistry and process research is that low cost can be correlated to environmental benignity when the costs of disposing wastes are high. This Perspective then highlights five synthetic strategies that satisfy several of the criteria of green chemistry: (1) polymerization using metal-mediated cross-coupling reactions that reduce or eliminate stoichiometric organotin waste; (2) the use of heterogeneously catalyzed polymerizations; (3) polymerization involving activation of C–H bonds; (4) use of biofeedstock-derived starting materials; and (5) polycondensation reactions that evolve water as a byproduct.

Chun-Ho Wong, S. Zimmerman