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ABSTRACT: Mass spectrometry is now an indispensable tool for lipid analysis and is arguably the driving force in the renaissance of lipid research. In its various forms, mass spectrometry is uniquely capable of resolving the extensive compositional and structural diversity of lipids in biological systems. Furthermore, it provides the ability to accurately quantify molecular-level changes in lipid populations associated with changes in metabolism and environment; bringing lipid science to the "omics" age. The recent explosion of mass spectrometry-based surface analysis techniques is fuelling further expansion of the lipidomics field. This is evidenced by the numerous papers published on the subject of mass spectrometric imaging of lipids in recent years. While imaging mass spectrometry provides new and exciting possibilities, it is but one of the many opportunities direct surface analysis offers the lipid researcher. In this review we describe the current state-of-the-art in the direct surface analysis of lipids with a focus on tissue sections, intact cells and thin-layer chromatography substrates. The suitability of these different approaches towards analysis of the major lipid classes along with their current and potential applications in the field of lipid analysis are evaluated.
Progress in lipid research 04/2013; · 10.67 Impact Factor
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ABSTRACT: The development of cell printing is vital for establishing biofabrication approaches as clinically relevant tools. Achieving this requires bio-inks which must not only be easily printable, but also allow controllable and reproducible printing of cells. This review outlines the general principles and current progress and compares the advantages and challenges for the most widely used biofabrication techniques for printing cells: extrusion, laser, microvalve, inkjet and tissue fragment printing. It is expected that significant advances in cell printing will result from synergistic combinations of these techniques and lead to optimised resolution, throughput and the overall complexity of printed constructs.
Applied Microbiology and Biotechnology 03/2013; · 3.42 Impact Factor
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ABSTRACT: Unsaturated lipids deposited onto a range of materials are observed to react with the low concentrations of ozone present in normal laboratory air. Parent lipids and ozonolysis cleavage products are both detected directly from surfaces by desorption electrospray ionisation mass spectrometry (DESI-MS) with the resulting mass spectra providing clear evidence of the double bond position within these molecules. This serendipitous process has been coupled with thin-layer chromatography (TLC) to provide a simple but powerful approach for the detailed structural elucidation of lipids present in complex biological extracts. Lipid extracts from human lens were deposited onto normal phase TLC plates and then developed to separate components according to lipid class. Exposure of the developed plates to laboratory air for ca. 1 h prior to DESI-MS analysis gave rise to ozonolysis products allowing for the unambiguous identification of double bond positions in even low abundant, unsaturated lipids. In particular, the co-localization of intact unsaturated lactosylceramides (LacCer) with products from their oxidative cleavage provide the first evidence for the presence of three isomeric LacCer (d18:0/24:1) species in the ocular lens lipidome, i.e., variants with double bonds at the n-9, n-7 and n-5 positions.
The Analyst 11/2011; 137(5):1100-10. · 4.23 Impact Factor
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Soft Matter 01/2011; 7(10):4690-4695. · 4.39 Impact Factor
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ABSTRACT: The electrical resistance of carbon nanotube networks (NNs) prepared from combinations of gellan gum, xanthan gum, Triton X-100, SWNT and MWNT is reported. It is demonstrated that the NN conductivity can be obtained by analysing the resistance of two overlapping NN as a function of their overlap distance. Unexpectedly, the connectivity between two overlapping NN was found to scale with the electrical conductivity over 4 orders of magnitude. Insights into the dependence of inter-NN contact on applied pressure were obtained.
Nanoscale 09/2010; 2(9):1740-5. · 5.91 Impact Factor
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ABSTRACT: The lipid composition of the human lens is distinct from most other tissues in that it is high in dihydrosphingomyelin and the most abundant glycerophospholipids in the lens are unusual 1-O-alkyl-ether linked phosphatidylethanolamines and phosphatidylserines. In this study, desorption electrospray ionization (DESI) mass spectrometry-imaging was used to determine the distribution of these lipids in the human lens along with other lipids including, ceramides, ceramide-1-phosphates, and lyso 1-O-alkyl ethers. To achieve this, 25 μm lens slices were mounted onto glass slides and analyzed using a linear ion-trap mass spectrometer equipped with a custom-built, 2-D automated DESI source. In contrast to other tissues that have been previously analyzed by DESI, the presence of a strong acid in the spray solvent was required to desorb lipids directly from lens tissue. Distinctive distributions were observed for [M + H](+) ions arising from each lipid class. Of particular interest were ionized 1-O-alkyl phosphatidylethanolamines and phosphatidylserines, PE (18:1e/18:1), and PS (18:1e/18:1), which were found in a thin ring in the outermost region of the lens. This distribution was confirmed by quantitative analysis of lenses that were sectioned into four distinct regions (outer, barrier, inner, and core), extracted and analyzed by electrospray ionization tandem mass spectrometry. DESI-imaging also revealed a complementary distribution for the structurally-related lyso 1-O-alkyl phosphatidylethanolamine, LPE (18:1e), which was localized closer to the centre of the lens. The data obtained in this study indicate that DESI-imaging is a powerful tool for determining the spatial distribution of human lens lipids.
Journal of the American Society for Mass Spectrometry 09/2010; 21(12):2095-104. · 4.00 Impact Factor
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ABSTRACT: Entirely nanostructured nanofibrilar-polyaniline/multi-walled carbon nanotube (NF-PANI/MWNT) composites with nanotube loadings as highas 50 wt% were synthesized via a facile in-situ chemical polymerization process. These are composed of a nanofibrilar polyaniline (NF-PANI) matrix in which multi-walled carbon nanotubes (MWNTs) are homogeneously embedded and partially covered by polyaniline. Stable and homogeneous aqueous dispersions in concentrations up to 10 mg/ml in water easily were prepared. For the first time, dispersions and casted films of this novel type of NF-PANI/MWNTs composites are characterized. Both, dispersions and films reveal the typical behavior of PANI with slightly changed redox values and with fast reaction kinetics due to the presence of MWNTs. Conductivity of drop cast films reveal values of 20 to 50 S/m. Local SPM measurements confirm the intrinsic fibril structure. Individual fibrils show both semiconducting and metallic behavior with values up to 100 S/m. This new class of nanostructured NF-PANI/MWNT composites with its water-based processing possibilities as well as with its conducting and electrochromic effects will contribute to further progress in the field of smart plastic electronics.
Journal of Nanoscience and Nanotechnology 09/2009; 9(10):6157-6163. · 1.56 Impact Factor
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ABSTRACT: A simple continuous flow wet-spinning method to achieve mechanical reinforcement of the two oppositely charged biopolymers chitosan and gellan gum is described. The mechanical properties of these biopolymers are influenced by the order of addition. Using a facile method for mechanical reinforcement of gellan gum/chitosan fibers resulted in increases in Young's modulus, tensile strength, and toughness. Spinning gellan gum into chitosan resulted in the strongest fibers. We show that our fibers can provide a mechanical alternative for bio-fibers without the need of cross-linking. It is demonstrated that the fibers become ionically conducting in the presence of water vapor.
Macromolecular Bioscience 12/2008; 9(4):354-60. · 3.89 Impact Factor
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ABSTRACT: Optically active composite materials were prepared by in situ polymerization of aniline in the presence of multiwalled carbon nanotubes, followed by doping with (R)-(-)-10-camphorsulfonic acid. The reduction in circular dichroism intensity with increasing nanotube loading fraction is attributed to changes in the ratio of “free” polymer versus polymer interacting with carbon nanotubes. These changes are shown to correspond to a decreasing polyaniline stereoselectivity with increasing nanotube loading fraction University of Wollongong internal funding. Australian Research Council. MEC: MAT2006-13167-C02-02 DGA-PIP021/2005 Peer reviewed
The Journal of Physical Chemistry C 01/2008; 112(5):1441-1445. · 4.80 Impact Factor
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Small 10/2007; 3(9):1500-3. · 8.35 Impact Factor
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ABSTRACT: The in-situ polymerization of aniline in the presence of multiwalled carbon nanotubes and (S)-(+)-10-camphorsulfonic acid provides a route to optically active composite materials. Their chiroptical properties suggest that polymers and composite materials adopt similar optical properties indicative of “compact coil” in DMSO and “extended coil” in m-cresol. The optical activity in composite materials is preserved, although somewhat reduced to that of the pure polymer, which is attributed to the polymer phase coating nanotubes. This polymer phase is responsible for the lower electrical resistance observed for composite materials.
Macromolecules 09/2006; 39(21):7324–7332. · 5.17 Impact Factor
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ABSTRACT: Fabrication of single-walled carbon nanotube (SWNT) networks using evaporation of SDS-SWNT sessile drops on a hydrophobized silicon substrate is reported. It is suggested that the organization of nanotubes during evaporation is controlled by aggregates (in the SDS-SWNT dispersion) and hydrophobicity of the substrate. On hydrophobic substrates, the evaporation of SDS-SWNT sessile drops proceeds through constant contact area. On hydrophilic substrates, nanotube aggregates in SDS-SWNT dispersion stop the contact line from moving, resulting in the formation of "coffee-stains". The (partial) removal of aggregates by centrifugation is essential for a freely moving contact line leading to the organization of nanotubes into a network of homogeneously distributed nanotubes on the most hydrophobic substrate. The evaporation of sessile drops was characterized by microscopic, spectroscopic, and topographical techniques.
The Journal of Physical Chemistry B 08/2006; 110(26):13029-36. · 3.70 Impact Factor
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ABSTRACT: A completely soluble optically active polyaniline-multiwalled carbon nanotube composite was investigated by spectroscopic and microscopic techniques. It was found that the polymer's optical activity was retained in the presence of carbon nanotubes. Solutions were found to be easily processable into thin films, which exhibited dendritic structures only in the presence of nanotubes.
The Journal of Physical Chemistry B 01/2006; 109(48):22725-9. · 3.70 Impact Factor
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Marc in het Panhuis,
Srinivas Gowrisanker,
Douglas J Vanesko,
Charles A Mire,
Huiping Jia,
Hui Xie,
Ray H Baughman,
Inga H Musselman,
Bruce E Gnade,
Gregg R Dieckmann,
Rockford K Draper
Small 09/2005; 1(8-9):820-3. · 8.35 Impact Factor
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ABSTRACT: The interaction between redox polymers, based on Ru- or Os-bis(2,2'-bipyridyl)-poly(4-vinylpyridine), and carbon nanotubes was investigated by spectroscopic and microscopic techniques. These metallopolymers were found to be excellent dispersants for nanotubes, as a result of a good wetting interaction between polymer and nanotubes. The results obtained show that well-coated individual nanotubes can be obtained. In addition, interactions between nanotubes and polymers did not significantly affect the electronic and electrochemical properties of the metallopolymers. On the basis of the electrochemical properties of the polymers this opens the possibility of adding functionality through interaction with nanotubes, either as redox active materials with enhanced mechanical properties or by using these modified nanotubes as nanosized electrochemical sensors.
The Journal of Physical Chemistry B 08/2005; 109(27):13205-9. · 3.70 Impact Factor
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ABSTRACT: Novel micro-capsules (carbon nanotubosomes) have been fabricated by cross-linking shells of amine-functionalized multi-walled carbon nanotubes (MWNTs) produced by their adsorption on water-in-oil emulsion drops followed by an emulsion-inversion.
Chemical Communications 05/2005; · 6.17 Impact Factor
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ABSTRACT: The interaction of single wall carbon nanotubes (SWNT) with an aqueous solution of the fully sulfonated polyaniline poly(2-methoxyaniline-5-sulfonic acid) (PMAS) and (+)-1-phenylethylamine (PhEA) has been investigated using spectroscopic methods. UV-vis spectral measurements show that the PMAS backbone undergoes conformational changes upon interaction with both SWNT and PhEA. Partial intercalation of PMAS into SWNTbundles was confirmed by Raman spectroscopy and electron microscopy.
Journal of Nanoscience and Nanotechnology 12/2004; 4(8):976-81. · 1.56 Impact Factor
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Marc in het Panhuis
Chemistry & Biology 11/2003; 10(10):897-8. · 5.83 Impact Factor
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ABSTRACT: Carbon nanotubes (CNTs) did not exhibit strong interactions with Biliverdin IX beta reductase enzyme (BVRB) in water. With the use of noncovalent functionalization by the surfactant Triton X-100, the surfaces of the CNTs were changed from hydrophobic to hydrophilic. The hydrophilic surface of the CNT-Triton conjugate interacts with the hydrophilic surface of BVRB, thus creating a water-soluble complex. Results from ultracentrifugation through a sucrose gradient and gel electrophoresis show the presence of the enzyme. Raman spectroscopy confirmed that the enzyme indeed interacts with CNT-Triton conjugates.
Journal of Nanoscience and Nanotechnology 07/2003; 3(3):209-13. · 1.56 Impact Factor
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Fiona Frehill,
Johannes G Vos,
Sakina Benrezzak,
Antal A Koós,
Zoltan Kónya,
Manuel G Rüther,
Werner J Blau,
Antonio Fonseca,
Janos B Nagy,
Laszlo P Biró,
Andrew I Minett, Marc In Het Panhuis
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ABSTRACT: Intermolecular carbon nanotube junctions were formed through amide linkage of amino functionalized multiwall carbon nanotubes and [Ru (dcbpy)(bpy)2](PF6)2, an inorganic metal complex. Nanotube interconnects were visualized using atomic force microscopy. Absorption and emission spectroscopy showed significant changes between starting products and the resulting ruthenium nanotube complex, indicative of successful chemical modification.
Journal of the American Chemical Society 12/2002; 124(46):13694-5. · 9.91 Impact Factor
