Dermot BroughamDublin City University | DCU · School of Chemical Sciences
Dermot Brougham
BSc, PhD
About
71
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Introduction
Publications
Publications (71)
We present a novel approach for the preparation of magnetic nanoparticle clusters of controlled size and selectable magnetic anisotropy, which provides materials with properties selectable for biomedical applications and as components in magnetically responsive nanocomposites. The assembly process is based on a ligand desorption strategy and allows...
The synthesis of coordinatively unsaturated tetra-substituted 1,4,7,10-tetraazacyclododecane (cyclen) lanthanide complexes is described; these structures, possessing hydrophobic (C12-alkyl) tails and hydrophilic head groups, self-assemble into supramolecular micellar structures in aqueous solution, and hence can be utilised as novel contrast agents...
Clusters or assemblies of nanoparticles exhibit unique features which arise from the enhancement of properties of single nanoparticles or due to new collective properties. On page 5400, D. F. Brougham and co-workers review the role of nanoparticle interactions in controlling cluster formation, and classify the assembly mechanisms. Emerging applicat...
Lysine-glyco-copolypeptide grafted superparamagnetic iron oxide nanoparticles were prepared through N-carboxyanhydride (NCA) copolymerization. Statistical and block copolymer arrangements were obtained while keeping the overall composition constant. Both type of nanoparticles are fully water dispersible, which is key for T1-weighted magnetic resona...
In this study controlled clustering kinetics is demonstrated for PEG grafted gold nanoparticles, in response to applied envi-ronmental stimuli; the temperature and ionic strength of the medium. It is also found that the rate of assembly determines the structure of the prepared clusters. After the system is brought out of equilibrium, time-dependent...
The current state of the art in the use of colloidal methods to form nanoparticle assemblies, or clusters (NPCs) is reviewed. The focus is on the two-step approach, which exploits the advantages of bottom-up wet chemical NP synthesis procedures, with subsequent colloidal destabilization to trigger assembly in a controlled manner. Recent successes i...
We report a scalable and reproducible method to assemble magnetic nanoparticle clusters from oleic acid stabilised iron oxide nanoparticles. By controlling the surface coverage of oleic acid on the nanoparticle surface we have achieved controlled nanoparticle assembly following exposure of the suspension to a substrate layer of cyanopropyl-modified...
Nanoalloys and nanocomposites are widely studied classes of nanomaterials within the context of biological systems. These are of immense interest because of the possibility of tuning the optical, magnetic, electronic and chemical properties through particle composition and internal architecture. In principle these properties can therefore be tuned...
The catalytic performance of a range of nanocrystalline CeO2 samples, prepared to have different morphologies, was measured using two accepted indicators; oxygen storage and diesel soot combustion. The same powders were characterized in detail by HR-TEM, XRD, XPS and Raman methods. The study demonstrates that activity is determined by the relative...
Citrate-stabilised iron oxide nanoparticles (∼16 nm) have been immobilised on commercial silica monolithic centrifugal spin columns (MonoSpin) for the extraction of phosphorylated compounds. Two alternative strategies were adopted involving either direct electrostatic attachment to an aminated MonoSpin (single-layer method) in the first instance, o...
Given the promise of carbon nanotubes (CNTs) for photothermal therapy, drug delivery, tissue engineering, and gene therapy, there is a need for non-invasive imaging methods to monitor CNT distribution and fate in the body. In this study, non-ionizing whole-body high field magnetic resonance imaging (MRI) is used to follow the distribution of water-...
Liposomes, loaded with gadolinium (Gd) ions using different membrane-incorporated chelating lipids and functionalized with monoclonal anti-CD138 (syndecan-1) antibody were prepared. Nuclear Magnetic Resonance Dispersion (NMRD) analysis showed that use of the polychelating amphiphilic polymer (PAP) increases both the Gd content and the spin–lattice...
The general applicability of fast field-cycling nuclear magnetic resonance relaxometry in the study of dynamics in lipid bilayers is demonstrated through analysis of binary unilamellar liposomes composed of 1,2-dioleoyl-sn-glycero-3-posphocholine (DOPC) and cholesterol. We extend an evidence-based method to simulating the NMR relaxation response, p...
A method for providing nanoparticle clusters of controlled dimensions is described. The method involves an activation of individual nanoparticles and the subsequent interaction between activated particles to form a cluster.
Sweet nanomagnets: Suspensions of glycopeptide grafted magnetic nanoparticles can be produced by N-carboxyanhydride ring-opening polymerization with subsequent click glycosylation. The resulting materials have a high sugar density, optimal dispersion and T(1) -weighted MRI properties, and bio-recognition ability. The approach can be used to attach...
We report the binding of nanoparticles (NPs) to wild type (unmodified) Tobacco mosaic virus (TMV). The viruses are simply mixed with citrate-coated, negatively charged gold and iron oxide nanoparticles (IONPs) in acidic solution. This results in TMV decorated along its whole length by the respective particles. Such a decoration usually requires che...
In the pursuit of optimized magnetic nanostructures for diagnostic and therapeutic applications, the role of nanoparticle architecture has been poorly investigated. In this study, we demonstrate that the internal collective organization of multi-core iron oxide nanoparticles can modulate their magnetic properties in such a way as to critically enha...
LiMo(3)Se(3) is a highly anisotropic solid comprised of a regular pattern of quasi-1-D wire-like structures. Solutions of LiMo(3)Se(3) deposited on substrates and TEM grids reveal the presence of two-dimensional network morphologies. High resolution STEM imaging reveals that the junctions within these networks are not formed by discrete overlying L...
A simple one-pot green chemical method for the biosynthesis of gold nanoparticles (AuNPs) by reducing chloroauric acid (HAuCl4) with protein extract of Rhizopus oryzae to produce novel gold nano-bio-conjugates (AuNBC) is described. AuNBCs, having sizes ranging from 5 to 65 nm, were synthesized by altering the HAuCl4–protein extract ratio. The conju...
In recent years there has been rapid progress in the development of nanomaterials, and in particular magnetic nanomaterials, for magnetic resonance imaging and other biomedical applications. Using selected highlights from recent literature we describe the magnetic resonance methods that are used to measure the effects of agents on image contrast. W...
AbstractA novel and efficient method to produce water dispersible superparamagnetic Fe3O4 nanoparticles is described. Nanoparticles prepared by non‐hydrolytic organic phase methods are subsequently functionalized with (3‐glycidyloxypropyl)trimethoxysilane, a linker that prevents aggregation and is available for subsequent coupling reactions with a...
Cellulose nanocrystals (CNCs) were prepared by acidic hydrolysis of cotton fibers (Whatman #1 filter paper). In our efforts
to select conditions in which the hydrolysis media does not install labile protons on the cellulose crystals, a mineral acid
other than sulfuric acid (H2SO4) was used. Furthermore, in our attempts to increase the yields of nan...
Ultrasmall superparamagnetic Fe(3)O(4) nanoparticles (USIRONs) were synthesized by a novel, easily scalable chemical reduction of colloidal iron hydroxide under hydrothermal conditions. The average crystallite size (5.1 ± 0.5 nm) and good crystallinity of the samples were supported by HR-TEM analysis and the saturation magnetization value (47 emu g...
Gliotoxin, a redox-active metabolite, is produced by the opportunistic fungal pathogen Aspergillus fumigatus, and its biosynthesis is directed by the gli gene cluster. Knowledge of the biosynthetic pathway to gliotoxin, which contains a disulfide bridge of unknown origin, is limited, although L-Phe and L-Ser are known biosynthetic precursors. Delet...
Polyelectrolyte-stabilised cobalt ferrite magnetic fluids demonstrate high relaxivity values at low fields. The magnetic suspensions are composed of compact metal oxide nanocomposites arranged in micelle-like structures which demonstrate an inverse correlation between relaxivity and hydrodynamic diameter (see graph). They can be aligned into linear...
New methods to study dynamics in lipid bilayers are of interest particularly where they may bridge the gap between conventional experimental techniques and molecular dynamics simulations. Fast field cycling nuclear magnetic resonance relaxometry can provide valuable information as it is sensitive to dynamic processes that occur over a broad time sc...
We present a new route to stable magnetic-plasmonic nanocomposite materials with exceptional control over composite size and very high monodispersity. The method involves the assembly of magnetic iron oxide nanoparticles, of any size in the superparamagnetic size range, whose steric repulsion is gradually reduced by competitive stabilizer desorptio...
The sections in this article are
We report the successful classification, by artificial neural networks (ANNs), of (1)H NMR spectroscopic data recorded on whole-cell culture samples of four different lung carcinoma cell lines, which display different drug resistance patterns. The robustness of the approach was demonstrated by its ability to classify the cell line correctly in 100%...
Stable aqueous suspensions of phospholipid-coated superparamagnetic Fe3O4nanoparticles, or magnetoliposomes (MLs), were prepared and were separated by magnetic chromatography into size monodisperse fractions over a broad size range (50–130 nm). This development facilitated the first study of the size dependence of the MRI relaxation enhancements (r...
We report the physico-chemical characterisation of fatty acid stabilised aqueous magnetic fluids, which are ideal systems for studying the influence of nanoparticle aggregation on the emergent magnetic resonance properties of the suspensions. Stable colloids of superparamagnetic magnetite, Fe(3)O(4), nanoparticle clusters in the 80 to 100 nm size r...
Supplementary figure 1: Scores plot for the entire data set; group 1 solid markers, group 2 open markers.
Fast field-cycling (FFC) and rotating-frame nuclear magnetic resonance relaxometry were used to study molecular and collective dynamics in unilamellar liposome systems. Relaxation data for liposomes of diameter about 100 nm composed of 1,2-dimyristoyl-sn-glycero-3-posphocholine (DMPC) or 1,2-dioleoyl-sn-glycero-3-posphocholine (DOPC) were obtained....
The design, preparation and characterization of poly(butylcyanoacrylate) nanoparticles as a drug-delivery system for daunorubicin is reported. A range of light scattering [photon correlation spectroscopy (PCS)], spectroscopic [(1)H nuclear magnetic resonance ((1)H NMR), Fourier transform infrared (FTIR), chromatographic [gel permeation chromatograp...
Größenkontrollierte Cluster von 15 nm großen superparamagnetischen Eisenoxidnanopartikeln mit Ölsäurebeschichtung wurden durch partielle Destabilisierung von Suspensionen der dispergierten Nanopartikel mit CN-modifiziertem Kieselgel hergestellt. Der Effekt induziert die graduelle Bildung der monodispersen superparamagnetischen Cluster, indem die fe...
We report the preparation of monodisperse maghemite (gamma-Fe2O3) nanoparticle suspensions in heptane, by thermal decomposition of iron(III) acetylacetonate in the presence of oleic acid and oleylamine surfactants. By varying the surfactant/Fe precursor mole ratio during synthesis, control was exerted both over the nanocrystal core size, in the ran...
Fast-field cycling NMR relaxometry been applied to investigate dynamic processes in the conducting polymer, polyaniline. For a group of samples with different concentrations of the dopant trifluoromethanesulfonic acid, the 1H spin−lattice relaxation rates exhibit power law dependence on the Larmor frequency. The powers obtained are found to increas...
We report principal component analysis (PCA) of (1)H NMR spectra recorded for a group of human lung carcinoma cell lines in culture and (1)H NMR analysis of extracts from the same samples. The samples studied were cells of lung tumour origin with different chemotherapy drug resistance patterns. For whole cells, it was found that the statistically s...
We report synthesis and studies of magnetic suspensions with tunable low-field relaxivities. Using a one-step procedure, we have prepared magnetic fluids composed of polyelectrolyte stabilized magnetite nanoparticles. We have demonstrated the effect of varying the synthetic conditions, in particular, the iron and PSSS polyelectrolyte content for a...
Using a one-step procedure we have prepared magnetic fluids comprising of polyelectrolyte stabilized magnetite nanoparticles. These nanocomposites are comprised of linear, chain-like assemblies of magnetic nanoparticles, which can be aligned in parallel arrays by an external magnetic field. We have shown the potential use of these materials as cont...
Fast-field cycling 19F NMR relaxometry has been applied to investigate fluoride ion dynamics in the layered anionic conductor PbSnF4. Two dynamic processes, on different timescales, were shown to drive the 19F relaxation. By considering the temperature dependencies of the NMR, conductivity, and diffraction data, a complete mechanism for fluoride tr...
A preliminary application of diffusion-ordered spectroscopy (DOSY) for separation, identification and characterisation of metabolites of human lung carcinoma cell extracts, exhibiting different levels of multi-drug resistance (MDR) is reported. The results show the presence of at least three lipid components of different sizes in the lipophilic ext...
The room temperature growth and ordering of copper(II) 2,9,16,23-tetra-tert-butyl-phthalocyanine (CuTtertBuPc) molecules on the Ag/Si(111)- surface have been investigated using scanning tunnelling microscopy/spectroscopy (STM/STS). Results indicate a well-ordered molecular layer in which the phthalocyanine molecules have a flat orientation with the...
Two homochiral tripodal receptors were characterised by X-ray crystallography, the first examples for this class of imidazolium receptor. These receptors were also screened for anion recognition. Both receptors demonstrated selectivity towards chloride and bromide with binding constants as high as 16,000.
Fluorescent magnetite nanocomposites based on magnetic nanoparticles, a polyhedral octaaminopropylsilsesquioxane and a porphyrin derivative have been prepared. The intracellular uptake of the nanocomposites by macrophage and bone osteoblast cells, and their potential as MRI contrast agents, has been demonstrated.
Nuclear magnetic resonance dispersion (NMRD) is a technique for measuring NMR relaxation times, which is commonly used to study dynamics in condensed matter. In this paper, we present NMRD profiles, for polyanilines doped with trifluoromethanesulfonic acid (TFSA), recorded as a function of temperature and dopant concentration. This work demonstrate...
[reaction: see text] The macrocyclic cyclen conjugates 1-4 were synthesized with the aim of forming lanthanide ion-based macrocyclic conjugates possessing deep cavities, formed upon complexation to various lanthanide ions. These complexes all possess metal-bound water molecules, where the pKa of the water molecules depends on the nature of the cavi...
Denatured (substantially single-stranded) herring sperm DNA acts as a template for the preparation of magnetic nanowires, forming stable aqueous suspensions, which exhibit unprecedentedly high relaxivity at low field, suggesting that the material may be a potentially useful reagent for MRI.
An extensive literature has emerged on the use of nuclear magnetic resonance (NMR) relaxation methods for the determination of various petrophysical properties such as porosity, permeability, initial water saturation and free fluid index. Although observations were first made in the 1950s, relatively few papers have appeared, which use NMR methods...
Double-proton transfer in the hydrogen bonds of the benzoic acid dimer is described by an asymmetric double-well potential. At low temperature, the hydrogen bond dynamics are dominated by phonon-assisted tunnelling and the correlation time for proton transfer is independent of temperature. We report proton transfer measurements on samples that inco...
The transfer of protons involved in hydrogen bonding is fundamental
to many chemical and biological processes. Quantum
tunnelling can play an important role in this process1,2. It manifests
itself in strong isotope effects3,4 and has been observed
directly in the solid state5. The tunnelling behaviour seen in
such studies usually displays the chara...
The dynamics of proton transfer along the hydrogen bonds of dimers of benzoic acid has been characterized in single crystals and powders at temperatures between 10 K and 110 K by quasi-elastic neutron scattering (QENS) and by proton spin-lattice relaxation using field-cycling NMR spectroscopy. These measurements define the geometry of the proton tr...
Double proton transfer in the hydrogen bonds of carboxylic acid dimers has been investigated via measurements of the dispersion of the proton spin-lattice relaxation time, T1, using magnetic field-cycling NMR. A plot of the spin-lattice relaxation rate, T1−1, as a function of magnetic field, provides a direct measurement of the motional spectrum an...
The incoherent tunnelling rate for proton transfer in the hydrogen bonds of benzoic acid dimers has been measured by field cycling NMR from the dispersion of the proton spin-lattice relaxation time which maps out the spectral density function directly. The intermediate region between quantum and classical dynamics has been studied by measuring the...
Quantum mechanical tunneling involving proton displacements in molecular crystals is investigated by optical spectroscopy,
nuclear magnetic resonance and neutron scattering as well as numerical modeling. Tunneling, depending exponentially on the
properties of the potential barriers, is used to gain information about potential energy surfaces and to...
The dynamic behavior of [(C(6)H(7))Fe(CO)(3)]BF(4) (I) and [(C(7)H(9))Fe(CO)(3)]BF(4) (II) in the solid state has been investigated principally by NMR spectroscopy. High-resolution variable-temperature (1)H and (13)C NMR spectra indicate that both complexes have a solid state phase transition above which there is rapid reorientation of the cyclodie...
The dynamic behavior of [(C6H7)Fe(CO)(3)]BF4 (I) and [(C7H9)Fe(CO)(3)]BF4 (II) in the solid state has been investigated principally by NMR spectroscopy. High-resolution variable-temperature H-1 and C-13 NMR spectra indicate that both complexes have a solid state phase transition above which there is rapid reorientation of the cyclodienylium rings a...
We report a correlation between the rate of incoherent tunneling associated with proton transfer in hydrogen bonds and the structure of aromatic carboxylic acid dimers. The compressibility of the hydrogen bond in benzoic acid, specifically the oxygen–oxygen distance r(O⋅⋅O), has been measured as a function of hydrostatic pressure up to 3.2 kbar usi...
In a series of organometallic carbonyl complexes, hydride ligands which experience weak dipolar interactions and other ligands (tert-butyl, NH3) which have dipolar interactions moderated by intramolecular motion in the solid state give well resolved solid state H-1 MAS NMR spectra. This establishes solid state H-1 NMR as a valuble structural tool,...
Ab initio molecular orbital calculations on [Mn(CO)(6)](+), [Mn(CO)(5)(PH3)](+), and the formyl and hydride complexes derived from these show that the increased stability of cis-Mn(CO)(4)(PR(3))(CHO) and similar formyl complexes is largely kinetic in origin. The transition state for the unsubstituted formyl complex, which forms the corresponding hy...
Ab initio MO calculations at the QCISD(T)/6–31G* */MP2/6–31G* * + ZPE level on the XX′CP2 isomers (X = H1 F and Cl) show that the energies of the isomeric species are often reordered following halogen substitution. The phosphorushalogen moiety behaves as the main stabilizing factor on the rest of the molecular structure. This is particularly true w...
in Electrical Related Properties of Organic Solids, NATO Advanced Series (Kluwer Academic Press) p369 (1997)
Projects
Projects (2)
RADIOMAG was a European COST action (TD1402) aiming to bring together and to organise the research outcomes from the different participating network members in a practical way to provide clinicians with the necessary input to trial a novel anti-cancer treatment combining magnetic hyperthermia and radiotherapy, also identifying future research objectives upon appraisal of the obtained results.