scholarly journals Aqueous dispersions of oligomer-grafted carbon nanomaterials with controlled surface charge and minimal framework damage

2014 ◽  
Vol 173 ◽  
pp. 273-285 ◽  
Author(s):  
Sheng Hu ◽  
Shu Chen ◽  
Robert Menzel ◽  
Angela D. Goode ◽  
Mary P. Ryan ◽  
...  
Keyword(s):  
Surface Charge ◽  
Carbon Nanomaterials ◽  
Water Solubility ◽  
Thermochemical Treatment ◽  
High Water ◽  
Ionic Character ◽  
Gravimetric Analysis ◽  
Physiochemical Properties ◽  
Toxicological Effects ◽  
Wide Range

Functionalised carbon nanomaterials (CNMs), with an undamaged carbon framework and controlled physiochemical properties, are desirable for a wide range of scientific studies and commercial applications. The use of a thermochemical grafting approach provides a versatile means to functionalise both multi-walled carbon nanotubes (MWCNTs) and carbon black (CB) nanoparticles without altering their inherent structures. The functionalisation process was investigated by employing various types of grafting monomers; to improve water solubility, reagents were chosen that introduced an ionic character either intrinsically or after further chemical reactions. The degree of grafting for both MWCNTs and CB ranged from 3–27 wt%, as established by thermal gravimetric analysis (TGA). Raman spectroscopy confirmed that the structural framework of the MWCNTs was unaffected by the thermochemical treatment. The effectiveness of the surface modification was demonstrated by significantly improved dispersibility and stability in water, and further quantified by zeta-potential analysis. The concentration of stable, individualised and grafted MWCNTs in water ranged from ∼30 to 80 μg mL−1after centrifugation at 10 000 g for 15 min, whereas functionalised CB in water showed improved dispersibility up to ∼460 μg mL−1. The successful preparation of structurally identical but differently functionalised nanoparticle panels, with high water compatibility and minimal framework damage, is useful for controlled experiments. For example, they can be used to explore the relationship between toxicological effects and specific physiochemical properties, such as surface charge and geometry.

Recent Advances in the Synthetic Chemistry of Bicyclo[1.1.1]pentane

Synlett ◽  
2018 ◽  
Vol 30 (01) ◽  
pp. 1-11 ◽  
Author(s):  
Junichiro Kanazawa ◽  
Masanobu Uchiyama
Keyword(s):  
Water Solubility ◽  
Chemical Space ◽  
Direct Synthesis ◽  
Three Dimensional ◽  
High Water ◽  
Synthetic Chemistry ◽  
Drug Candidates ◽  
Recent Advances ◽  
Wide Range ◽  
Phenyl Rings

Utilization of three-dimensional cyclic scaffolds is important in modern drug discovery, both to provide greater opportunities for optimizing drug candidates and to expand the available chemical space of drugs. Among these scaffolds, bicyclo[1.1.1]pentane (BCP) is a high-value bioisostere for 1,4-disubstituted phenyl rings, internal alkynes, and the tert-butyl group, generally offering high passive permeability, high water solubility, and improved metabolic stability. However, the lack of methods for functionalizing BCP remains a significant challenge, and in particular, a versatile strategy for synthesizing a wide range of unsymmetrically 1,3-difunctionalized BCP derivatives has been lacking. In this account, we review recent advances in the synthetic chemistry of BCP, focusing especially on our recently developed radical multicomponent carboamination of [1.1.1]propellane.1 Introduction2 Overview of the Synthetic Chemistry of [1.1.1]Propellane, the Most Promising Precursor of Bicyclo[1.1.1]pentane3 Recent Advances in the Synthetic Chemistry of Unsymmetrically 1,3-Disubstituted Bicyclo[1.1.1]pentane Derivatives4 Radical Multicomponent Carboamination of [1.1.1]Propellane Permits Direct Synthesis of 3-Substituted Bicyclo[1.1.1]pent-1-ylamine Derivatives5 Conclusion

scholarly journals Design principles and biological applications of red-emissive two-photon carbon dots

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Pooria Lesani ◽  
Aina Hazeera Mohamad Hadi ◽  
Zufu Lu ◽  
Stefano Palomba ◽  
Elizabeth J. New ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Near Infrared ◽  
Water Solubility ◽  
High Water ◽  
Photon Absorption ◽  
Biological Applications ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Current State ◽  
Wide Range

AbstractCarbon dots have been gaining attention in the field of nanobiotechnology due to their superior photostability, high water solubility, ease of synthesis and surface functionalization, chemical inertness, low toxicity, and excellent biocompatibility. They also exhibit good two-photon absorption and unique tunable optical properties across a wide range of wavelengths, from ultraviolet to near infrared endowing them with potential for a variety of biological applications. Recently, there has been a growing interest in the synthesis and development of red-emissive two-photon carbon dots. Here we present recent progress in the design requirements for red-emissive two-photon carbon dots, and review current state-of-the-art systems, covering their applications in bioimaging, biosensing, and photothermal and photodynamic therapy.

A review of the composition and evolution of hydrocarbon gases during solidification of the Ilímaussaq alkaline complex, South Greenland

2001 ◽  
pp. 159-166 ◽  
Author(s):  
Jens Konnerup-Madsen
Keyword(s):  
Nepheline Syenite ◽  
Subsequent Development ◽  
High Water ◽  
Vapour Phase ◽  
Low Carbon ◽  
Low Oxygen ◽  
Alkaline Complex ◽  
Hydrocarbon Gases ◽  
Wide Range ◽  
Water Contents

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Konnerup-Madsen, J. (2001). A review of the composition and evolution of hydrocarbon gases during solidification of the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin, 190, 159-166. https://doi.org/10.34194/ggub.v190.5187 _______________ Fluid inclusions in minerals from agpaitic nepheline syenites and hydrothermal veins in the Ilímaussaq complex and in similar agpaitic complexes on the Kola Peninsula, Russia, are dominated by hydrocarbon gases (predominantly methane) and hydrogen. Such volatile compositions differ considerably from those of most other igneous rocks and their formation and entrapment in minerals reflects low oxygen fugacities and a wide range of crystallisation temperatures extending to a low-temperature solidus. Their composition reflects initial low carbon contents and high water contents of the magma resulting in the exsolution of a waterrich CO2–H2O dominated vapour phase. Fractionation of chlorides into the vapour phase results in high salinities and the subsequent development of a heterogeneous vapour phase with a highly saline aqueous-rich fraction and a methane-dominated fraction, with preferential entrapment of the latter, possibly due to different wetting characteristics. The light stable isotope compositions support an abiogenic origin for the hydrocarbons in agpaitic nepheline syenite complexes.

scholarly journals Rheology and Water Absorption Properties of Alginate–Soy Protein Composites

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1807
Author(s):  
Estefanía Álvarez-Castillo ◽  
José Manuel Aguilar ◽  
Carlos Bengoechea ◽  
María Luisa López-Castejón ◽  
Antonio Guerrero
Keyword(s):  
Soy Protein ◽  
Water Solubility ◽  
Divalent Cations ◽  
Low Cost ◽  
Soy Protein Isolate ◽  
Protein Isolate ◽  
Guluronic Acid ◽  
Wide Range ◽  
Anionic Polysaccharides ◽  
Porous Matrices

Composite materials based on proteins and carbohydrates normally offer improved water solubility, biodegradability, and biocompatibility, which make them attractive for a wide range of applications. Soy protein isolate (SPI) has shown superabsorbent properties that are useful in fields such as agriculture. Alginate salts (ALG) are linear anionic polysaccharides obtained at a low cost from brown algae, displaying a good enough biocompatibility to be considered for medical applications. As alginates are quite hydrophilic, the exchange of ions from guluronic acid present in its molecular structure with divalent cations, particularly Ca2+, may induce its gelation, which would inhibit its solubilization in water. Both biopolymers SPI and ALG were used to produce composites through injection moulding using glycerol (Gly) as a plasticizer. Different biopolymer/plasticizer ratios were employed, and the SPI/ALG ratio within the biopolymer fraction was also varied. Furthermore, composites were immersed in different CaCl2 solutions to inhibit the amount of soluble matter loss and to enhance the mechanical properties of the resulting porous matrices. The main goal of the present work was the development and characterization of green porous matrices with inhibited solubility thanks to the gelation of alginate.

scholarly journals Application of Dendrimers for Treating Parasitic Diseases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 343
Author(s):  
Veronica Folliero ◽  
Carla Zannella ◽  
Annalisa Chianese ◽  
Debora Stelitano ◽  
Annalisa Ambrosino ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Water Solubility ◽  
Parasitic Infection ◽  
Three Dimensional ◽  
Medical Knowledge ◽  
High Ratio ◽  
Molecular Volume ◽  
Parasitic Infections ◽  
Parasitic Diseases ◽  
Wide Range

Despite advances in medical knowledge, parasitic diseases remain a significant global health burden and their pharmacological treatment is often hampered by drug toxicity. Therefore, drug delivery systems may provide useful advantages when used in combination with conventional therapeutic compounds. Dendrimers are three-dimensional polymeric structures, characterized by a central core, branches and terminal functional groups. These nanostructures are known for their defined structure, great water solubility, biocompatibility and high encapsulation ability against a wide range of molecules. Furthermore, the high ratio between terminal groups and molecular volume render them a hopeful vector for drug delivery. These nanostructures offer several advantages compared to conventional drugs for the treatment of parasitic infection. Dendrimers deliver drugs to target sites with reduced dosage, solving side effects that occur with accepted marketed drugs. In recent years, extensive progress has been made towards the use of dendrimers for therapeutic, prophylactic and diagnostic purposes for the management of parasitic infections. The present review highlights the potential of several dendrimers in the management of parasitic diseases.

Hydraulic segmentation does not protect stems from acute water loss during fire

2021 ◽  
Author(s):  
William A Hoffmann ◽  
Amanda C Rodrigues ◽  
Nicholas Uncles ◽  
Lorenzo Rossi
Keyword(s):  
Water Uptake ◽  
Water Loss ◽  
High Water ◽  
Fire Plume ◽  
Magnolia Grandiflora ◽  
Hydraulic Failure ◽  
Factors Influencing ◽  
Wide Range ◽  
Transport Path ◽  
Measured Water

Abstract The heat plume associated with fire has been hypothesized to cause sufficient water loss from trees to induce embolism and hydraulic failure. However, it is unclear whether the water transport path remains sufficiently intact during scorching or burning of foliage to sustain high water loss. We measured water uptake by branches of Magnolia grandiflora while exposing them to a range of fire intensities, and examined factors influencing continued water uptake after fire. Burning caused a 22-fold mean increase in water uptake, with greatest rates of water loss observed at burn intensities that caused complete consumption of leaves. Such rapid uptake is possible only with steep gradients in water potential, which would likely result in substantial cavitation of xylem and loss of conductivity in intact stems. Water uptake continued after burning was complete, and was greatest following burn intensities that killed leaves but did not consume them. This post-fire uptake was mostly driven by rehydration of the remaining tissues, rather than evaporation from the tissues. Our results indicate that the fire-plume hypothesis can be expanded to include a wide range of burning conditions experienced by plants. High rates of water loss are sustained during burning, even when leaves are killed or completely consumed.

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.

A Fluorescence Quenching Analysis of the Binding of Fluoroquinolones to Humic Acid

2017 ◽  
Vol 71 (11) ◽  
pp. 2512-2518 ◽  
Author(s):  
Ryan P. Ferrie ◽  
Gregory E. Hewitt ◽  
Bruce D. Anderson
Keyword(s):  
Humic Acid ◽  
Fluorescence Quenching ◽  
Water Solubility ◽  
Binding Constants ◽  
High Water ◽  
Static Quenching ◽  
Temperature Range ◽  
Equilibrium Binding ◽  
Quenching Analysis ◽  
High Water Solubility

Fluorescence quenching was used to investigate the interaction of six fluoroquinolones with humic acid. Static quenching was observed for the binding of ciprofloxacin, enoxacin, fleroxacin, levofloxacin, norfloxacin, and ofloxacin to humic acid. The equilibrium binding constants were found from Stern–Volmer plots of the data. The quenching experiments were repeated over a temperature range of 25–45 ℃ and van’t Hoff plots were generated. From these linear plots, thermodynamic values were calculated for Δ H, Δ G, and Δ S for each of the fluoroquinolones. The equilibrium binding constants were found to be <1 for all the antibiotics studied. The calculated ΔH values were all negative and ranged from −9.5 to −27.6 kJ/mol. The high water solubility of the antibiotics and low ΔH of binding suggests that the antibiotics will be transported easily through the environment. Finally, whether the fluoroquinolones are in a protonated, deprotonated, or partially protonated state is found to correlate to the strength of binding to humic acid.

Novel tetrazole PtII and PdII complexes with enhanced water solubility: synthesis, structural characterization and evaluation of antiproliferative activity

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Tatiyana V. Serebryanskaya ◽  
Alexander S. Lyakhov ◽  
Ludmila S. Ivashkevich ◽  
Yuri V. Grigoriev ◽  
Andreii S. Kritchenkov ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Performance ◽  
Water Solubility ◽  
Thermal Analyses ◽  
High Water ◽  
Acetonitrile Solution ◽  
X Ray ◽  
Molecular And Crystal Structures ◽  
Tetrazole Derivatives ◽  
High Water Solubility

AbstractNovel platinum(II) and palladium(II) chlorido complexes with tetrazole derivatives 1-(2-hydroxyethyl)tetrazole (het) and 1-[tris(hydroxymethyl)methyl]tetrazole (thm), viz. cis-[Pt(het)2Cl2], trans-[Pt(het)2Cl2], trans-[Pt(thm)2Cl2], trans-[Pd(het)2Cl2], and trans-[Pd(thm)2Cl2], were synthesized. The compounds were characterized by elemental and high-resolution electrospray ionization (HRESI) mass spectrometry, high-performance liquid chromatography (HPLC), 1H, 13C and 195Pt nuclear magnetic resonance (NMR) spectroscopy, thermal analyses, and Infrared (IR) spectroscopy. Molecular and crystal structures of trans-[PdL2Cl2] and trans-[PtL2Cl2] (L = het, thm) were established by single-crystal X-ray analysis. The complex cis-[Pt(het)2Cl2] was found to undergo cis–to–trans isomerization upon heating in acetonitrile solution and in the solid state. The synthesized complexes show rather high water solubility lying in the range of 2–10 mg/L.

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