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276 results on '"Brougham, Dermot F."'

2. Nuclear spin relaxation in aqueous paramagnetic ion solutions

Author

Faux, David A., Istók, Örs, Rahaman, Arifah A., McDonald, Peter J., McKiernan, Eoin, and Brougham, Dermot F.

Subjects
Condensed Matter - Other Condensed Matter, Physics - Chemical Physics
Abstract

An angular time-dependent probability density function describing Brownian or anomalous rotational dynamics of fixed-length atom-to-atom vectors is presented. The probability density function, which fully incorporates angular boundary conditions, is applied to aqueous ion complexes. The rotational dynamics of ion-$^1$H vectors are shown by molecular dynamics (MD) simulation to be Brownian. A Brownian shell model is presented which yields a closed form expression for the frequency-dependent nuclear-magnetic-resonance spin-lattice relaxation rate $T_1^{-1}(\omega)$ based on a distance parameter and time constant. Appropriate combinations of shell and/or continuum models are shown to provide excellent fully-quantitative fits to experimental $T_1^{-1}(\omega)$ dispersion curves from aqueous manganese(II), iron(III) and copper(II) chloride solutions. The distance parameters and time constants obtained from the fits are in good agreement with independent experimental and MD data in the literature. The Brownian shell model is a significant enhancement to existing particle-particle models that describe the rotational correlation function as a single exponential and are unable to provide the correct distance dependence for a shell of $^1$H spin density preventing a match to experiment without an arbitrary scaling factor., Comment: 39 pages, 7 figures, includes an appendix

Published
2021

13. Reproducible Synthesis of Biocompatible Albumin Nanoparticles Designed for Intra-articular Administration of Celecoxib to Treat Osteoarthritis

Author

Khandelia, Rumi, primary, Hodgkinson, Tom, additional, Crean, Daniel, additional, Brougham, Dermot F., additional, Scholz, Dimitri, additional, Ibrahim, Hossam, additional, Quinn, Susan J., additional, Rodriguez, Brian J., additional, Kennedy, Oran D., additional, O’Byrne, John M., additional, and Brayden, David J., additional

Published
2024
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20. Surface Potential Modulation in Boronate-Functionalized Magnetic Nanoparticles Reveals Binding Interactions: Toward Magnetophoretic Capture/Quantitation of Sugars from Extracellular Matrix

Author

Universidad de Alicante. Departamento de Química Analítica, Nutrición y Bromatología, Universidad de Alicante. Instituto Universitario de Materiales, Lyons, Stephen, Baile, Paola, Vidal, Lorena, McGarry, Katie, Morrin, Aoife, Brougham, Dermot F., Universidad de Alicante. Departamento de Química Analítica, Nutrición y Bromatología, Universidad de Alicante. Instituto Universitario de Materiales, Lyons, Stephen, Baile, Paola, Vidal, Lorena, McGarry, Katie, Morrin, Aoife, and Brougham, Dermot F.

Abstract

Phenylboronic acids (BAs) are important synthetic receptors that bind reversibly to cis-diols enabling their use in molecular sensing. When conjugated to magnetic iron oxide nanoparticles, BAs have potential for application in separations and enrichment. Realizing this will require a new understanding of their inherent binding modes and measurement of their binding capacity and their stability in/extractability from complex environments. In this work, 3-aminophenylboronic acid was functionalized to superparamagnetic iron oxide nanoparticles (MNPs, core diameter 8.9 nm) to provide stable aqueous suspensions of functionalized particles (BA-MNPs). The progress of sugar binding and its impact on BA-MNP colloidal stability were monitored through the pH-dependence of hydrodynamic size and zeta potential during incubation with a range of saccharides. This provided the first direct observation of boronate ionization pKa in grafted BA, which in the absence of sugar shifted to a slightly more basic pH than free BA. On exposure to sugar solutions under MNP-limiting conditions, pKa moved progressively to lower pH as maximum capacity was gradually attained. The pKa shift is shown to be greater for sugars with greater BA binding affinity, and on-particle sugar exchange effects were inferred. Colloidal dispersion of BA-MNPs after binding was shown for all sugars at all pHs studied, which enabled facile magnetic extraction of glucose from agarose and cultured extracellular matrix expanded in serum-free media. Bound glucose, quantified following magnetophoretic capture, was found to be proportional to the solution glucose content under glucose-limiting conditions expected for the application. The implications for the development of MNP-immobilized ligands for selective magnetic biomarker capture and quantitation from the extracellular environment are discussed.

Published
2023

21. A holistic NMR framework to understand environmental impact: Examining the impacts of superparamagnetic iron oxide nanoparticles (SPIONs) in Daphnia magna via imaging, spectroscopy, and metabolomics.

Author

Jenne, Amy, Soong, Ronald, Gruschke, Oliver, Bastawrous, Monica, Monks, Patricia, Moloney, Cara, Brougham, Dermot F., Busse, Falko, Bermel, Wolfgang, Courtier‐Murias, Denis, Wu, Bing, and Simpson, Andre

Subjects
IRON oxide nanoparticles, DAPHNIA magna, NUCLEAR magnetic resonance spectroscopy, METABOLOMICS, FOOD additives, TOXICITY testing, BINDING energy
Abstract

Superparamagnetic iron oxide nanoparticles (SPIONs) are a contaminant of emerging interest, often used in the medical field as an imaging contrast agent, with additional uses in wastewater treatment and as food additives. Although the use of SPIONs is increasing, little research has been conducted on the toxic impacts to living organisms beyond traditional lethal concentration endpoints. Daphnia magna are model organisms for aquatic toxicity testing with a well understood metabolome and high sensitivity to SPIONs. Thus, as environmental concentrations continue to increase, it is becoming critical to understand their sub‐lethal toxicity. Due to the paramagnetic nature of SPIONs, a range of potential nuclear magnetic resonance spectroscopy (NMR) experiments are possible, offering the potential to probe the physical location (via imaging), binding (via relaxation weighted spectroscopy), and the biochemical pathways impacted (via in vivo metabolomics). Results indicate binding to carbohydrates, likely chitin in the exoskeleton, along with a decrease in energy metabolites and specific biomarkers of oxidative stress. The holistic NMR framework used here helps provide a more comprehensive understanding of SPIONs impacts on D. magna and showcases NMR's versatility in providing physical, chemical, and biochemical insights. [ABSTRACT FROM AUTHOR]

Published
2023
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25. A holistic NMR framework to understand environmental impact: Examining the impacts of superparamagnetic iron oxide nanoparticles (SPIONs) inDaphnia magnavia imaging, spectroscopy, and metabolomics

Author

Jenne, Amy, primary, Soong, Ronald, additional, Gruschke, Oliver, additional, Bastawrous, Monica, additional, Monks, Patricia, additional, Moloney, Cara, additional, Brougham, Dermot F., additional, Busse, Falko, additional, Bermel, Wolfgang, additional, Courtier‐Murias, Denis, additional, Wu, Bing, additional, and Simpson, Andre, additional

Published
2022
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28. Modulation of hyperthermic and relaxometric responses of magnetic iron oxide nanoparticles through ligand exchange provides design criteria for dual-functionality.

Author

Aluri, Esther Rani, Shingte, Sameer D., McKiernan, Eoin P., Ferguson, Steven, and Brougham, Dermot F.

Abstract

Magnetic iron oxide nanoparticles (MNPs) are the subject of intense study as theranostic tools that combine magnetic resonance imaging (MRI)-trackability with AC-field responsive heating. In this study, we report MNPs synthesised using a modification of an established thermal decomposition method which, following extensive parameter optimisation, provides strong hyperthermic heating efficacy that is reproducible batch to batch. The suspensions have an exceptional specific absorption rate of ∼2800 W g−1 (intrinsic loss power, ILP ∼20.4 W m2 g−1 kA−2 kHz−1) within a high concentration range (collective particle scenario) falling to ∼1000 W g−1 (∼7.9 W m2 g−1 kA−2 kHz−1) on full dispersion by dilution. The effect of stabilising ligand surface chemistry on the concentration-dependent hyperthermic and MRI efficacies was evaluated by ligand exchange/phase transfer from organic to aqueous and back to organic suspension, and on the formation of organogels. Fast field-cycling NMR relaxometry of the different suspensions reveals the role of moment dynamics and of subtle differences in particle and solvent diffusion in determining both the hyperthermic and relaxometric efficacies. These insights identify particle design compromises that are required to simultaneously optimise MNPs for the two applications. [ABSTRACT FROM AUTHOR]

Published
2023
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36. Electrostatically modulated magnetophoretic transport of functionalised iron-oxide nanoparticles through hydrated networks

Author

Lyons, Stephen, McKiernan, Eoin P., Dee, Garret, Brougham, Dermot F., Morrin, Aoife, Lyons, Stephen, McKiernan, Eoin P., Dee, Garret, Brougham, Dermot F., and Morrin, Aoife

Abstract

Factors that determine magnetophoretic transport of magnetic nanoparticles (MNPs) through hydrated polymer networks under the influence of an external magnetic field gradient were studied. Functionalised iron oxide cores (8.9 nm core diameter) were tracked in real-time as they moved through agarose gels under the influence of an inhomogeneous magnetic field. Terminal magnetophoretic velocities were observed in all cases, these were quantified and found to be highly reproducible and sensitive to the con- ditions. Increasing agarose content reduced magnetophoretic velocity, we attribute this to increasingly tortuous paths through the porous hydrated polymer network and propose a new factor to quantify the tortuosity. The impact of MNP surface functionalisation, charge, network fixed charge content, and ionic strength of the aqueous phase on velocity were studied to separate these effects. For MNPs functionalised with polyethylene glycol (PEG) increasing chain length reduced velocity but the tortuosity extracted, which is a function of the network, was unchanged; validating the approach. For charged citrate- and arginine-functionalised MNPs, magnetophoretic velocities were found to increase for particles with posi- tive and decrease for particles with negative zeta potential. In both cases these effects could be moder- ated by reducing the number of agarose anionic residues and/or increasing the ionic strength of the aqueous phase; conditions under which tortuosity again becomes the critical factor. A model for MNP transport identifying the contributions from the tortuous pore network and from electrostatic effects associated with the pore constrictions is proposed.

Published
2020

45. Novel injectable gallium-based self-setting glass alginate hydrogel composite for cardiovascular tissue engineering

Author

Clarkin, Owen, Wu, Bing, Cahill, Paul A., Brougham, Dermot F., Banerjee, Dipanjan, Brady, Sarah, Fox, Eoin, and Lally, Caitríona

Subjects
glass, alginate, aneurysm, cardiovascular, polyalkenoate, Biomedical engineering
Abstract

Composite biomaterials offer a new approach for engineering novel, minimally-invasive scaffolds with properties that can be modified for a range of soft tissue applications. In this study, a new way of controlling the gelation of alginate hydrogels using Ga-based glass particles is presented. Through a comprehensive analysis, it was shown that the setting time, mechanical strength, stiffness and degradation properties of this composite can all be tailored for various applications. Specifically, the hydrogel generated through using a glass particle, wherein toxic aluminium is replaced with biocompatible gallium, exhibited enhanced properties. The material’s stiffness matches that of soft tissues, while it displays a slow and tuneable gelation rate, making it a suitable candidate for minimally-invasive intra-vascular injection. In addition, it was also found that this composite can be tailored to deliver ions into the local cellular environment without affecting platelet adhesion or compromising viability of vascular cells in vitro.

Published
2019

46. Solid state dynamics of tricarbonyl(eta-1,5-cyclohexadienylium)iron tetrafluoroborate and tricarbonyl(eta-1,5-cycloheptadienylium)iron tetrafluoroborate

Author

Brougham, Dermot F., Barrie, Patrick J., Hawkes, Geoffrey E., Abrahams, Isaac, Motevalli, Majid, Brown, David A., and Long, Gary J.

Subjects
Borates -- Research, Carbonyl compounds -- Research, Iron compounds -- Research, Chemistry
Abstract

The dynamics of the complexes ((eta5-C6H7)Fe(CO)3)BF4 and ((eta5-C7H9)Fe(CO)3)BF4 are analyzed by nuclear magnetic resonance spectroscopy in solid state. Both complexes exhibit dynamic processes at elevated temperatures by going through a phase transition. The phase transition temperature is higher for the cycloheptadienyl than the cyclohexadienyl. Such observation implies greater hindrance to the motion for the more sterically hindered cation. The motion consists of a fast and complete reorientation of the molecule.

Published
1996

47. Facile Approach for Synthesizing High-Performance MnO/C Electrodes from Rice Husk

Author

Zhan, Dan (author), Luo, Wei (author), Kraatz, Heinz Bernhard (author), Fehse, M. (author), Li, Yuqi (author), Xiao, Zuoan (author), Brougham, Dermot F. (author), Simpson, André J. (author), Wu, Bing (author), Zhan, Dan (author), Luo, Wei (author), Kraatz, Heinz Bernhard (author), Fehse, M. (author), Li, Yuqi (author), Xiao, Zuoan (author), Brougham, Dermot F. (author), Simpson, André J. (author), and Wu, Bing (author)

Abstract

Pyrolysis is an effective way to convert biomass into biofuel while obtaining highly porous active carbon materials. In this study, a facile approach, involving hydrothermal and pyrolysis steps, is described for preparing hybrid metal oxide nanoparticle-embedded porous hard carbon matrices (MnO/C) from the biowaste rice husk and organometallic precursors. It was found that the pyrolysis/calcination temperature had a strong influence over the microstructure, especially over the porosity, but also over the carbon content and crystallinity of the nanocomposites; hence, the electrical properties can be controlled. Galvanostatic measurements showed that the nanocomposite obtained at 600 °C exhibited the highest charge/discharge capacity and best stability, delivering an initial discharge capacity of 1104 mA·h·g-1 at a current density of 200 mA·g-1, and retaining a value of 830 mA·h·g-1 after 200 cycles, suggesting excellent cycle stability. A discharge capacity of 581 mA·h·g-1 was obtained even at a current density as high as 2400 mA·g-1, demonstrating superb rate capability. This outstanding electrochemical performance, ascribed to high electrochemical activity of the embedded MnO nanoparticles enhanced by electrical conductivity provided through the high surface area of the active porous carbon support, is discussed in relation to the microstructure of the nanocomposite., RST/Storage of Electrochemical Energy

Published
2019
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50. Facile Green Route to Ni/Co Oxide Nanoparticle Embedded 3D Graphitic Carbon Nanosheets for High Performance Hybrid Supercapacitor Devices

Author

Xiang, Cuili, primary, Liu, Yin, additional, Yin, Ying, additional, Huang, Pengru, additional, Zou, Yongjin, additional, Fehse, Marcus, additional, She, Zhe, additional, Xu, Fen, additional, Banerjee, Dipanjan, additional, Hermida Merino, Daniel, additional, Longo, Alessandro, additional, Kraatz, Heinz-Bernhard, additional, Brougham, Dermot F., additional, Wu, Bing, additional, and Sun, Lixian, additional

Published
2019
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