Results
- Showing results for:
- Reset all filters
Search results
-
Journal articleLaurent D, Vinet L, Lamprianou S, et al., 2016,
Pancreatic β-cell imaging in humans: fiction or option?
, Diabetes Obesity & Metabolism, Vol: 18, Pages: 6-15, ISSN: 1462-8902Diabetes mellitus is a growing worldwide epidemic disease, currently affecting 1 in 12 adults. Treatment of disease complications typically consumes ∼10% of healthcare budgets in developed societies. Whilst immune-mediated destruction of insulin-secreting pancreatic β cells is responsible for Type 1 diabetes, both the loss and dysfunction of these cells underly the more prevalent Type 2 diabetes. The establishment of robust drug development programmes aimed at β-cell restoration is still hampered by the absence of means to measure β-cell mass prospectively in vivo, an approach which would provide new opportunities for understanding disease mechanisms and ultimately assigning personalized treatments. In the present review, we describe the progress towards this goal achieved by the Innovative Medicines Initiative in Diabetes, a collaborative public–private consortium supported by the European Commission and by dedicated resources of pharmaceutical companies. We compare several of the available imaging methods and molecular targets and provide suggestions as to the likeliest to lead to tractable approaches. Furthermore, we discuss the simultaneous development of animal models that can be used to measure subtle changes in β-cell mass, a prerequisite for validating the clinical potential of the different imaging tracers.
-
Journal articleInkpen MS, Du S, Hildebrand M, et al., 2015,
The unusual redox properties of fluoroferrocenes revealed through a comprehensive study of the haloferrocenes
, Organometallics, Vol: 34, Pages: 5461-5469, ISSN: 1520-6041We report the synthesis and full characterization of the entire haloferrocene (FcX) and 1,1′-dihaloferrocene (fcX2) series (X = I, Br, Cl, F; Fc = ferrocenyl, fc = ferrocene-1,1′-diyl). Finalization of this simple, yet intriguing set of compounds has been delayed by synthetic challenges associated with the incorporation of fluorine substituents. Successful preparation of fluoroferrocene (FcF) and 1,1′-difluoroferrocene (fcF2) were ultimately achieved using reactions between the appropriate lithiated ferrocene species and N-fluorobenzenesulfonimide (NFSI). The crude reaction products, in addition to those resulting from analogous preparations of chloroferrocene (FcCl) and 1,1′-dichloroferrocene (fcCl2), were utilized as model systems to probe the limits of a previously reported “oxidative purification” methodology. From this investigation and careful solution voltammetry studies, we find that the fluorinated derivatives exhibit the lowest redox potentials of each of the FcX and fcX2 series. This counterintuitive result is discussed with reference to the spectroscopic, structural, and first-principles calculations of these and related materials.
-
Journal articleLong NJ, Stasiuk G, Gallo J, et al., 2015,
Tuning the relaxation rates of dual mode T1/T2 nanoparticle contrast agents: a study into the ideal system
, Nanoscale, Vol: 7, Pages: 16119-16128, ISSN: 2040-3372Magnetic resonance imaging (MRI) is an excellent imaging modality. However the low sensitivity of the technique poses a challenge to achieving an accurate image of function at the molecular level. To overcome this, contrast agents are used; typically gadolinium based agents for T1 weighted imaging, or iron oxide based agents for T2 imaging. Traditionally, only one imaging mode is used per diagnosis although several physiological situations are known to interfere with the signal induced by the contrast agents in each individual imaging mode acquisition. Recently, the combination of both T1 and T2 imaging capabilities into a single platform has emerged as a tool to reduce uncertainties in MR image analysis. To date, contradicting reports on the effect on the contrast of the coupling of a T1 and T2 agent have hampered the application of these specialised probes. Herein, we present a systematic experimental study on a range of gadolinium-labelled magnetite nanoparticles envisioned to bring some light into the mechanism of interaction between T1 and T2 components, and advance towards the design of efficient (dual) T1 and T2 MRI probes. Unexpected behaviours observed in some of the constructs will be discussed. In this study, we demonstrate that the relaxivity of such multimodal probes can be rationally tuned to obtain unmatched potentials in MR imaging, exemplified by preparation of the magnetite-based nanoparticle with the highest T2 relaxivity described to date.
-
Conference paperDuerrbeck A, Hor A, Long N, 2015,
New highly-emissive soluble dynamic Eu(III) coordination polymers for Ln(III) and transition metal sensing applications
, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727 -
Conference paperMiller P, Phanopoulos A, Long N, 2015,
Direct conversion of levulinic acid to 2-methyltetrahydrofuran using discrete Ru and Rh N-triphos catalysts
, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727 -
Journal articleAlbrecht T, Inkpen MS, Lemmer M, et al., 2015,
New insights into single-molecule junctions using a robust, unsupervised approach to data collection and analysis
, Journal of the American Chemical Society, ISSN: 1520-5126 -
SoftwareInkpen MS, Lemmer M, Fitzpatrick N, et al., 2015,
MATLAB script for data sorting
Supporting information associated with the publication "New insights into single-molecule junctions using a robust, unsupervised approach to data collection and analysis", J. Am. Chem. Soc., 2015, DOI: 10.1021/jacs.5b05693. This MATLAB script is a representative example of that used to objectively sort I(s) traces obtained from 1,8-ODT-coated and blank (uncoated) Au substrates. A short 'Guide to...' document is also included to introduce the user.
-
SoftwareInkpen M, Lemmer M, Fitzpatrick N, et al., 2015,
Macro Scheduler code for data collection
Supporting information associated with the publication "New insights into single-molecule junctions using a robust, unsupervised approach to data collection and analysis", J. Am. Chem. Soc., 2015, DOI: 10.1021/jacs.5b05693. This Macro Scheduler (MJT Net Ltd, UK) script is a representative example of that used to automatically measure I(s) traces from 1,8-ODT-coated and blank (uncoated) Au substrates using an Agilent 5100 Scanning Tunnelling Microscope (interfacing with PicoView 1.14, Agilent Technologies). A short 'Guide to...' document is also included to introduce the user, as are additional files (Microsoft Excel spreadsheets and images) required by the script.
-
Journal articlePhanopoulos A, Miller PW, Long NJ, 2015,
Beyond Triphos - New hinges for a classical chelating ligand
, Coordination Chemistry Reviews, Vol: 299, Pages: 39-60, ISSN: 1873-3840Branched triphosphine ligands have been less widely studied than mono- and bi-dentate analogues. The most studied ligand of this type is TriphosPh (CH3C(CH2PPh2)3). Substitution of the apical Csingle bondCH3 moiety with boron, silicon, tin, nitrogen or phosphorus fragments has generated a new family of ligands, in some cases displaying varying coordination chemistry and reactivity to the parent carbon-based system. This review includes the synthetic strategies implemented to afford these ligands, as well as derivatives by way of varying the phosphine substituents. Although not exhaustive, relevant types of reported complexes featuring these ligands are discussed, as well as their reactivity and catalytic applications. Through critical analysis, common themes and chemical trends across this family of apical heteroatomic, branched triphosphines can be identified, leading to improvements in current chemical applications, as well as new areas that remain underdeveloped.
-
Journal articlePhanopoulos A, White AJ, Long NJ, et al., 2015,
Catalytic transformation of levulinic acid to 2-methyltetrahydrofuran using ruthenium–N-triphos complexes
, ACS Catalysis, Vol: 5, Pages: 2500-2512, ISSN: 2155-5435A series of pre- or in situ-formed ruthenium complexes were assessed for the stepwise catalytic hydrogenation of levulinic acid (LA) to 2-methyltetrahydrofuran (2-MTHF) via γ-valerolactone (γVL) and 1,4-pentanediol (1,4-PDO). Two different catalytic systems based on the branched triphosphine ligands Triphos (CH3C(CH2PPh2)3) and N-triphos (N(CH2PPh2)3) were investigated. The most active catalyst was the preformed ruthenium species [RuH2(PPh3){N(CH2PPh2)3-κ3P}] (5), which gave near quantitative conversion of LA to 1,4-PDO when no acidic additives were present, and 87% 2-MTHF when used in conjunction with HN(Tf)2. Various acidic additives were assessed to promote the final transformation of 1,4-PDO to 2-MTHF; however, only HN(Tf)2 was found to be effective, and NH4PF6 and para-toluenesulfonic acid (p-TsOH) were found to be detrimental. Mechanistic investigations were carried out to explain the observed catalytic trends and importantly showed that PPh3 dissociation from 5 resulted in its improved catalytic reactivity. The presence of acidic additives removes catalytically necessary hydride ligands and may also compete with the substrate for binding to the catalytic metal center, explaining why only an acid with a noncoordinating conjugate base was effective. Crystals suitable for X-ray diffraction experiments were grown for two complexes: [Ru(NCMe)3{N(CH2PPh2)3-κ3P}] (14) and [Ru2(μ-Cl)3{N(CH2PPh2)3-κ3P}2][BPh4] (16).
-
Journal articlePhanopoulos A, Long N, Miller P, 2015,
The Synthesis, Characterization and Reactivity of a Series of Ruthenium <i>N</i>-triphos<SUP>Ph</SUP> Complexes
, JOVE-JOURNAL OF VISUALIZED EXPERIMENTS, ISSN: 1940-087X- Author Web Link
- Cite
- Citations: 4
-
Journal articleStasiuk GJ, Minuzzi F, Sae-Heng M, et al., 2015,
Dual-Modal Magnetic Resonance/Fluorescent Zinc Probes for Pancreatic beta-Cell Mass Imaging
, Chemistry-A European Journal, Vol: 21, Pages: 5023-5033, ISSN: 1521-3765: Despite the contribution of changes in pancreaticb-cell mass to the development of all forms of diabetes mellitus,few robust approaches currently exist to monitor thesechanges prospectively in vivo. Although magnetic-resonanceimaging (MRI) provides a potentially useful technique, targetingMRI-active probes to the b cell has proved challenging.Zinc ions are highly concentrated in the secretory granule,but they are relatively less abundant in the exocrinepancreas and in other tissues. We have therefore developedfunctional dual-modal probes based on transition-metal chelatescapable of binding zinc. The first of these, Gd·1, bindsZnII directly by means of an amidoquinoline moiety (AQA),thus causing a large ratiometric Stokes shift in the fluorescencefrom lem =410 to 500 nm with an increase in relaxivityfrom r1=4.2 up to 4.9 mm1 s1. The probe is efficiently accumulatedinto secretory granules in b-cell-derived lines andisolated islets, but more poorly by non-endocrine cells, andleads to a reduction in T1 in human islets. In vivo murinestudies of Gd·1 have shown accumulation of the probe inthe pancreas with increased signal intensity over 140 minutes.
-
Journal articleEdwards PP, Krebs B, Long NJ, et al., 2015,
Dedication to Lord Lewis: the new chemistry of the elements
, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 373, ISSN: 1364-503X -
Journal articleEdwards P, Krebs B, Raithby P, et al., 2015,
The new chemistry of the elements Introduction
, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 373, ISSN: 1364-503X- Author Web Link
- Cite
- Citations: 4
-
Journal articleBakewell C, Fateh-Iravani G, Beh D, et al., 2015,
Comparing a series of 8-quinolinolato complexes of aluminium, titanium and zinc as initiators for the ring-opening polymerization of rac-lactide.
, Dalton Transactions, Vol: 44, ISSN: 1477-9226The preparation and characterization of a series of 8-hydroxyquinoline ligands and their complexes with Ti(iv), Al(iii) and Zn(ii) centres is presented. The complexes are characterized using NMR spectroscopy, elemental analysis and, in some cases, by single crystal X-ray diffraction experiments. The complexes are compared as initiators for the ring-opening polymerization of racemic-lactide; all the complexes show moderate/good rates and high levels of polymerization control. In the case of the titanium or aluminium complexes, moderate iso-selectivity is observed (Pi = 0.75), whereas in the case of the zinc complexes, moderate hetero-selectivity is observed (Ps = 0.70).
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.
Contact
Professor Nick Long
Email: n.long@imperial.ac.uk
Telephone: +44 (0)20 7594 5781
Location
501J
Molecular Sciences Research Hub
White City Campus
