229 results found
Zhang G, Lin S, Leow CH, et al., 2019, Quantification of Vaporised Targeted Nanodroplets Using High-Frame-Rate Ultrasound and Optics., Ultrasound Med Biol
Molecular targeted nanodroplets that can extravasate beyond the vascular space have great potential to improve tumor detection and characterisation. High-frame-rate ultrasound, on the other hand, is an emerging tool for imaging at a frame rate one to two orders of magnitude higher than those of existing ultrasound systems. In this study, we used high-frame-rate ultrasound combined with optics to study the acoustic response and size distribution of folate receptor (FR)-targeted versus non-targeted (NT)-nanodroplets in vitro with MDA-MB-231 breast cancer cells immediately after ultrasound activation. A flow velocity mapping technique, Stokes' theory and optical microscopy were used to estimate the size of both floating and attached vaporised nanodroplets immediately after activation. The floating vaporised nanodroplets were on average more than seven times larger than vaporised nanodroplets attached to the cells. The results also indicated that the acoustic signal of vaporised FR-targeted-nanodroplets persisted after activation, with 70% of the acoustic signals still present 1 s after activation, compared with the vaporised NT-nanodroplets, for which only 40% of the acoustic signal remained. The optical microscopic images revealed on average six times more vaporised FR-targeted-nanodroplets generated with a wider range of diameters (from 4 to 68 µm) that were still attached to the cells, compared with vaporised NT-nanodroplets (from 1 to 7 µm) with non-specific binding after activation. The mean size of attached vaporised FR-targeted-nanodroplets was on average about threefold larger than that of attached vaporised NT-nanodroplets. Taking advantage of high-frame-rate contrast-enhanced ultrasound and optical microscopy, this study offers an improved understanding of the vaporisation of the targeted nanodroplets in terms of their size and acoustic response in comparison with NT-nanodroplets. Such understanding would help in the design of optimised methodolog
Jantan KA, McArdle JM, Mognon L, et al., 2019, Heteromultimetallic compounds based on polyfunctional carboxylate linkers, NEW JOURNAL OF CHEMISTRY, Vol: 43, Pages: 3199-3207, ISSN: 1144-0546
Rains JGD, ODonnelly K, Oliver T, et al., 2019, Bicarbonate inhibition of carbonic anhydrase mimics hinders catalytic efficiency: Elucidating the mechanism and gaining insight toward improving speed and efficiency, ACS Catalysis, Vol: 9, Pages: 1353-1365, ISSN: 2155-5435
Carbonic anhydrase (CA) mimics are often studied with a focus on the hydration of CO2 for atmospheric carbon capture. Consequently, the reverse reaction (dehydration of HCO3–) has received minimal attention, so much so that the rate-limiting step of the dehydration reaction in CA mimics is currently unknown. The rate-limiting step of the hydration reaction is reported to be the bicarbonate-bound intermediate step, and thus is susceptible to product inhibition. It is not, however, clear if this inhibition is a consequence of an increase in the rate of the competing dehydration reaction or resulting from the strong affinity of bicarbonate to the mimic. To address this, insight into the dehydration reaction kinetics is needed. We therefore report the most comprehensive study of a CA mimic to date. The dehydration profile of the fastest small-molecule CA mimic, ZnL1S, was characterized, and consequently evidence for the rate-limiting step for the dehydration reaction was seen to be the bicarbonate-bound intermediate step, much like the hydration reaction. This experimental validation of the rate-limiting step was achieved through a variety of methods including NMR experiments and the effect of inhibitors, substrate concentration, and metal center on activity. With this understanding, an improvement in the favorability of the rate-limiting step was achieved, resulting in decreased bicarbonate inhibition. Thus, an increase in the mimic’s kcat for both reactions was observed, resulting in the largest rate constants of any small-molecule CA mimic reported to date (28 093 and 579 M–1 s–1 for hydration and dehydration, respectively). Enzyme-like kcat/km values were obtained for ZnL1S (5.9 × 105 M–1 s–1 for CO2 hydration), and notably there is only a difference of 2.5 orders of magnitude from the enzyme, the closest of any CA mimic reported in the literature. The results from this work can be applied to the development and improvement
Wilkinson LA, Yue TTC, Massey E, et al., 2019, Cyanoferrocenes as redox-active metalloligands for coordination-driven self-assembly, DALTON TRANSACTIONS, Vol: 48, Pages: 72-78, ISSN: 1477-9226
Smith AJ, Gawne PJ, Ma MT, et al., 2018, Synthesis, gallium-68 radiolabelling and biological evaluation of a series of triarylphosphonium-functionalized DO3A chelators, DALTON TRANSACTIONS, Vol: 47, Pages: 15448-15457, ISSN: 1477-9226
Li B, Famili M, Pensa E, et al., 2018, Cross-plane conductance through a graphene/molecular monolayer/Au sandwich, NANOSCALE, Vol: 10, Pages: 19791-19798, ISSN: 2040-3364
Apps SL, White AJP, Miller PW, et al., 2018, Synthesis and reactivity of an N-triphos Mo(0) dinitrogen complex, Dalton Transactions, Vol: 47, Pages: 11386-11396, ISSN: 1477-9234
The preparation and reactivity of a novel molybdenum dinitrogen complex supported by a nitrogen-centred tripodal phosphine ligand (N-triphos, N(CH2PPh2)3, NP3Ph) are reported. Reaction of N-triphos with [MoX3(THF)3] (X = Cl, Br, I) gave the Mo(III) complex [MoX3(κ2-NP3Ph)(THF)] (1), where bidentate N-triphos coordination was observed. Reduction of this complex in the presence of dppm (bis(diphenylphosphino)methane) gave the dinitrogen complex [Mo(N2)(dppm)(κ3-NP3Ph)] (2), which exhibits moderate dinitrogen activation. An additional hydride complex, [Mo(H)2(dppm)(κ3-NP3Ph)] (4), was produced either as a minor side product during the reduction step, or as a major product by direct hydrogenation of the dinitrogen complex 2. The reactivity of the dinitrogen complex 2 with a range of Lewis acids was also investigated. At low temperatures, protic or borane Lewis acids (H+, BBr3 and tris(pentafluorophenyl)borane (BCF)) were found to coordinate to the apical nitrogen atom of the N-triphos ligand, with no conclusive evidence of any functionalisation of the dinitrogen ligand. Alkali metal Lewis acid addition to 2 resulted in the unexpected rearrangement of the N-triphos ligand to form [Mo(dppm)(PMePh2)(PCP)][B(C6F5)4] (7), where PCP, [Ph2PCNHCH2PPh2] is the carbenic ligand formed upon rearrangement from the reaction of 2 with M[B(C6F5)4] (M = Li, Na or K). Single crystal X-ray diffraction of complexes 1, 2, 4 and 7 provided structural confirmation of the N-triphos molybdenum complexes described.
Evans RJ, Hernandez-Gil J, Mohri Z, et al., 2018, DEVELOPING NEW TARGETED MOLECULAR CONTRAST AGENTS FOR IMAGING INFLAMMATION OF VULNERABLE PLAQUES, Annual Meeting of the British-Atherosclerosis-Society (BAS), Publisher: OXFORD UNIV PRESS, Pages: S3-S4, ISSN: 0008-6363
Wilson LE, Jian X, White AJP, et al., 2018, Synthesis and Characterisation of Linear and Towards Cyclic Diferrocenes with Alkynyl Spacers, INORGANICS, Vol: 6, ISSN: 2304-6740
Gawne P, Man F, Fonslet J, et al., 2018, Manganese-52: applications in cell radiolabelling and liposomal nanomedicine PET imaging using oxine (8-hydroxyquinoline) as an ionophore, DALTON TRANSACTIONS, Vol: 47, Pages: 9283-9293, ISSN: 1477-9226
Wang L, Long NJ, Li L, et al., 2018, Multi-functional bismuth-doped bioglasses: combining bioactivity and photothermal response for bone tumor treatment and tissue repair, LIGHT-SCIENCE & APPLICATIONS, Vol: 7, ISSN: 2047-7538
Zeng F, Wu Y, Li X, et al., 2018, Custom-Made Ceria Nanoparticles Show a Neuroprotective Effect by Modulating Phenotypic Polarization of the Microglia, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 57, Pages: 5808-5812, ISSN: 1433-7851
Price TW, Firth G, Eling CJ, et al., 2018, A F-18 radiolabelled Zn(II) sensing fluorescent probe, CHEMICAL COMMUNICATIONS, Vol: 54, Pages: 3227-3230, ISSN: 1359-7345
Bamber J, Shah A, Bush N, et al., Photoacoustic imaging and contrast agents in cancer research, Leeds Microbubble Symposium
Parker D, Long NJ, Faulkner S, 2017, Challenges for chemistry in molecular imaging, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 375, ISSN: 1364-503X
Leow CH, Braga M, Hernandez-Gil J, et al., 2017, Multi-frame rate plane wave contrast-enhanced ultrasound imaging for tumour vascular imaging and perfusion quantification, ISSN: 1948-5719
© 2017 IEEE. Angiogenesis and blood flow dynamics play an important role in the development of malignant tumours and their response to treatment. While contrast enhanced ultrasound (CEUS) imaging with microbubble contrast agents as a tool for imaging angiogenesis and flow dynamics has shown great potential , recent development of plane wave high frame-rate (HFR) CEUS has offered new opportunities in such applications. In this study, we demonstrate an interleaved multi-frame rate plane wave CEUS imaging to quantify perfusion and to image vascular structure with improved resolution and contrast.
Lin S, Shah A, Hernandez-Gil J, et al., 2017, Optically and acoustically triggerable sub-micron phase-change contrast agents for enhanced photoacoustic and ultrasound imaging, ISSN: 1948-5719
© 2017 IEEE. To explore the extravascular space, sub-micron phase-change droplets show widespread interest in medical imaging and therapy with various modalities, such as ultrasound and photoacoustic. Existing studies (Wilson 2012, Wei 2014) on such dual-modality contrast agents have demonstrated the generation of both optical and ultrasound contrast after optical activation. However these studies did not explore the option of acoustic activation. Furthermore, high boiling point perfluorocarbons were used in these studies. A low boiling point may be preferred, to minimise un-wanted bioeffects, especially when activating in deeper tissues. In this study, we demonstrate a versatile phase-change sub-micron contrast agent that can provide three modes of contrast enhancement: 1) photoacoustic imaging contrast, 2) ultrasound contrast with optical activation, and 3) ultrasound contrast with acoustic activation. This would add versatility of vaporisation triggering, offering new possibilities in dual mode imaging, molecular imaging and drug delivery.
Morse SV, Pouliopoulos AN, Chan T, et al., 2017, Rapid short-pulse (RaSP) sequences improve the distribution of drug delivery to the brain in vivo, ISSN: 1948-5719
© 2017 IEEE. Focused ultrasound and microbubbles have been shown to locally and noninvasively open the blood-brain barrier. Despite encouraging results in human patients, several performance and safety features, such as poor drug distribution, high drug accumulation along vessels and small sites of red blood cell extravasation, have been unavoidable. We have recently developed a new ultrasound sequence - rapid short-pulse (RaSP) sequence - designed to suppress these adverse features by promoting safer modes of cavitation activity throughout capillaries. In our RaSP sequences, low-pressure short ultrasonic pulses are emitted at kHz pulse repetition frequencies (PRF) and grouped into bursts. We have shown in vitro that RaSP sequences prolong microbubble lifetime and increase their mobility, enhancing the distribution of acoustic cavitation activity. Here we evaluate the ability of RaSP sequences to improve the in vivo performance and safety of ultrasound-mediated drug delivery to the brain.
Du S, Hernandez-Gil J, Dong H, et al., 2017, Design and validation of a new ratiometric intracellular pH imaging probe using lanthanide-doped upconverting nanoparticles, DALTON TRANSACTIONS, Vol: 46, Pages: 13957-13965, ISSN: 1477-9226
Leber R, Wilson LE, Robaschik P, et al., 2017, High-Vacuum Deposition of Biferrocene Thin Films on Room-Temperature Substrates, CHEMISTRY OF MATERIALS, Vol: 29, Pages: 8663-8669, ISSN: 0897-4756
Gallo J, Harriss BI, Hernandez-Gil J, et al., 2017, Probing T-1-T-2 interactions and their imaging implications through a thermally responsive nanoprobe, NANOSCALE, Vol: 9, Pages: 11318-11326, ISSN: 2040-3364
Al-Owaedi OA, Bock S, Milan DC, et al., 2017, Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions, NANOSCALE, Vol: 9, Pages: 9902-9912, ISSN: 2040-3364
Wilson LE, Hassenrueck C, Winter RF, et al., 2017, Ferrocene- and Biferrocene-Containing Macrocycles towards Single-Molecule Electronics, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 56, Pages: 6838-6842, ISSN: 1433-7851
Lin S, Shah A, Hernandez-Gil J, et al., 2017, Optically and acoustically triggerable sub-micron phase-change contrast agents for enhanced photoacoustic and ultrasound imaging, PHOTOACOUSTICS, Vol: 6, Pages: 26-36, ISSN: 2213-5979
McCluskey S, Plisson C, Long N, et al., 2017, Preclinical evaluation of [F-18]Mitophos_07 as an imaging agent for doxorubicin induced cardiotoxicity, Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), Publisher: SOC NUCLEAR MEDICINE INC, ISSN: 0161-5505
Coakley E, Long N, 2017, Dual-modal MR/NIR fluorescent probes for zinc sensing applications, 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Coleman C, Williams C, Long N, 2017, Asymmetric hybrid salen/phosphasalen initiators for the iso-selective ring-opening polymerisation of rac-lactide, 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Wilson L, Albrecht T, Long N, 2017, Delocalised chains and rings of ferrocenes, 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Anders DA, Bongarzone S, Fortt R, et al., 2017, Electrochemical [C-11]CO2 to [C-11]CO conversion for PET imaging, CHEMICAL COMMUNICATIONS, Vol: 53, Pages: 2982-2985, ISSN: 1359-7345
Bock S, Al-Owaedi OA, Eaves SG, et al., 2017, Single-Molecule Conductance Studies of Organometallic Complexes Bearing 3-Thienyl Contacting Groups, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 23, Pages: 2133-2143, ISSN: 0947-6539
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