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As a spectroscopic method, nuclear magnetic resonance (NMR) has seen spectacular growth over the past two decades, both as a technique and in its applications. Today the applications of NMR span a wide range of scientific disciplines, from physics to biology to medicine. Each volume of Nuclear Magnetic Resonance comprises a combination of annual and biennial reports which together provide comprehensive coverage of the literature on this topic. This Specialist Periodical Report reflects the growing volume of published work involving NMR techniques and applications, in particular NMR of natural macromolecules which is covered in two reports: "NMR of Proteins and Nucleic Acids" and "NMR of Carbohydrates, Lipids and Membranes". For those wanting to become rapidly acquainted with specific areas of NMR, this title provides unrivalled scope of coverage. Seasoned practitioners of NMR will find this an invaluable source of current methods and applications. Volume 33 covers literature published from June 2002 to May 2003. Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis.

Five commercial ionomer glasses (Fuji IX, Ketac Molar, G338, G2, and G2SR) used to produce glass (ionomer) polyalkenoate dental cements were studied. 29Si, 27Al, 31P and 19F magic angle spinning nuclear magnetic resonance (MAS-NMR) Spectroscopy was used to characterise the glasses and the resulting spectra compared with previous studies of model glasses. The 29Si NMR spectra were consistent with Q4(3Al) and Q4(4Al) units being present and agreed with the low non-bridging oxygen contents calculated from the elemental composition. The 27Al NMR spectra typically exhibited three distinct sites at 45-60, 20 and 0 ppm which have been attributed to Al(IV), Al(V) and Al(VI) coordinate aluminium. The presence of Al(V) and Al(VI) are consistent with previous studies of model ionomer glasses. The 31P spectra all exhibited a chemical shift between -8 and -23 ppm with the exception of the Ketac Molar glass, which exhibited a peak at 2-3 ppm consistent with orthophosphate. The chemical shift of 31P in the range -8 to -23 ppm indicates a PO(4) tetrahedra surrounded by 1-4 Al moieties. The (19)F NMR spectra indicated the presence of Al-F-Ca(n) in the G2 and G338 glasses, Al-F-Sr(n) in the G2SR and Fuji IX glasses and crystalline CaF2, LaF3, Al-F-Ca(n) in the Ketac Molar glass. The G338 glass with a high non-bridging oxygen content showed the presence of a F-Ca(n) species. There was also present in all the glasses a peak corresponding to Al-F-Na(n). The intensity of this peak was approximately proportional to the sodium content.

As a spectroscopic method, Nuclear Magnetic Resonance (NMR) has seen spectacular growth over the past two decades, both as a technique and in its applications. Today the applications of NMR span a wide range of scientific disciplines, from physics to biology to medicine. Each volume of Nuclear Magnetic Resonance comprises a combination of annual and biennial reports which together provide comprehensive of the literature on this topic. This Specialist Periodical Report reflects the growing volume of published work involving NMR techniques and applications, in particular NMR of natural macromolecules which is covered in two reports: "NMR of Proteins and Acids" and "NMR of Carbohydrates, Lipids and Membranes". For those wanting to become rapidly acquainted with specific areas of NMR, this title provides unrivalled scope of coverage. Seasoned practitioners of NMR will find this an in valuable source of current methods and applications. Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis.

When mixed with water, biological amphiphiles such as phospholipids can self-assemble to form a variety of lyotropic liquid crystalline structures including 1-D flat lamellar bilayers, 2-D hexagonal phases and 3-D bicontinuous cubic structures1. The role of the lamellar phase in nature is well understood – flat bilayers maintain the fundamental integrity of all living cells. However, non-lamellar phases also play a vital role in vivo. Extended cubic phases have been directly observed in cells and in addition, the repeating pores which form the continuously accessible structure of these bicontinuous phases are very closely structurally related to membrane pores formed during membrane fusion and fission. The equilibrium phase behaviour of pure phospholipids in water and simple model membrane mixtures has been widely studied but their out of equilibrium behaviour remains poorly understood. We have addressed this knowledge gap through pioneering work looking at the kinetics of phase transitions in phospholipid/water systems and phospholipid/protein/water mixtures using the pressure jump relaxation technique in conjunction with high speed, time resolved small angle X-ray diffraction. This presentation will provide an overview of how our bottom-up approach using model membrane systems has enabled us to establish the mechanistic routes and intermediates in a number of phase transition schemes including bicontinuous cubic to lamellar, hexagonal to lamellar and inter-cubic phase transitions.

Strontium-releasing injectable bone cements may have the potential to prevent implant-related infections through the bactericidal action of strontium, while enhancing bone formation in patients suffering from osteoporosis. A melt-derived bioactive glass (BG) series (SiO 2 –CaO–CaF 2 –MgO) with 0–50% of calcium substituted with strontium on a molar base were produced. By mixing glass powder, poly(acrylic acid) and water, cements were obtained which can be delivered by injection and set in situ , giving compressive strength of up to 35 MPa. Strontium release was dependent on BG composition with increasing strontium substitution resulting in higher concentrations in the medium. Bactericidal effects were tested on Staphylococcus aureus and Streptococcus faecalis ; cell counts were reduced by up to three orders of magnitude over 6 days. Results show that bactericidal action can be increased through BG strontium substitution, allowing for the design of novel antimicrobial and bone enhancing cements for use in vertebroplasty or kyphoplasty for treating osteoporosis-related vertebral compression fractures.

Vesicles serve important functions in the construction of artificial cells. They facilitate biochemical reactions by confining reactants and products in space, and delineate the boundaries of the protocell. They allow concentration gradients to form, and control the passage of molecules via embedded proteins. However, to date, manufacturing strategies have focussed on uni-compartmental structures, resulting in vesicles with homogenous internal content. This is in contrast to real cells which have spatial segregation of components and processes. We bridge this divide by fabricating networked multi-compartment vesicles. These were generated by encasing multiple water-in-oil droplets with an external bilayer, using a process of gravity-mediated phase-transfer. We were able to control the content of the compartments, and could define the vesicle architecture by varying the number of encased droplets. We demonstrated the bilayers were biologically functional by inserting protein channels, which facilitated material transfer between the internal compartments themselves, and between the compartments and their external environment. This paves the way for the construction of inter- and intra-vesicle communication networks. Importantly, multi-compartment vesicles allow the spatio-dynamic organisation seen in real cells to be introduced into artificial ones for the first time.

A centred-rectangular lyotropic ribbon phase, rarely observed in inverse (type II) systems, has been found in the branched-chain polyoxyethylene surfactant tetradecyloctadecyl-tetraoxyethylene ether (C14C16EO4) in excess water. This phase is stabilised by the application of hydrostatic pressure. The ratio of the 2-D cell parameters, b/a, is observed to be less than √3 (1.732) over the range of temperatures and pressures studied. The constructed pressure–temperature phase diagram shows that, at high temperatures or low pressures, the inverse ribbon phase converts into an inverse micellar cubic phase of spacegroup Fd3m, and at the opposite extreme, a lamellar gel phase was formed. The lattice parameters of the inverse ribbon phase were found to vary with pressure, with the structure becoming increasingly distorted away from 2-D hexagonal symmetry (b/a = √3) with increasing pressure.

Fluoride prevents dental cavities, stimulates bone mineralisation and decreases the melting temperature of glasses and is therefore an interesting component of bioactive glasses for use as dental or orthopaedic biomaterials. However, when designing new glass compositions, the structural role of fluoride in the glass needs to be better understood. We have characterised a glass series in the system SiO2–P2O5–CaO–Na2O with increasing concentrations of CaF2. Network connectivity was fixed at 2.13 by adding CaF2 while the ratio of all other components was kept constant. 19F and 29Si MAS NMR spectra showed that addition of CaF2 does not cause disruption of the glass network by formation of Si–F bonds but forms mixed calcium sodium fluoride species. 31P MAS NMR showed phosphate being present as orthophosphate. Hence it does not form part of the actual glass network backbone and no Si–O–P bonds are present. 23Na MAS NMR showed the presence of multiple sodium sites with an increase in the mean coordination number of sodium with increasing CaF2 content. The glass transition temperature decreased with increasing amounts of CaF2. As no Si–F bonds were formed, this can be explained by formation of hypothetical CaF+ species. The results can be used for designing new fluoride-containing bioactive glass compositions for specific applications.

NMR relaxation measurements, particularly ‘H spinlattice (thermal) relaxation times (TI’S), have been widely used to give an indication of the extent of conformational mobility existing within the macromolecular structure of coa1s.l-3 However, the influence of paramagnetic species on relaxation behavior makes interpretation of the results in terms of “rigid” and “mobile” phases far from easy. An alternative approach that has recently been applied to solid polymers is the use of l3C nuclear Overhauser enhancements ( N O E ’ S ) . ~ These are the fractional increases (0) in the observed intensities for particular 13C environments upon saturation of the ‘H absorptions and approach the maximium value of 1.99 (i.e., observed peak intensities are 1 + 9 or 2.99 times those in normal spectra) for groups that rapidly reorientate. In this communication, the first such measurements on a coal are reported and put into a general context by comparison with the values for a cross-linked polymer system. The pulse sequence usedG comprises the traditional Bloch decay or single pulse excitation (SPE) technique with a train of 1H 90° pulses for saturating the ‘H absorptions and a suitably long delay to ensure that complete spin-lattice relaxation of the 13C spins occurs. The 1H 90° pulses were separated by 1 ms to limit probe heating effects and can be applied for either the total or a fraction of the recycle delay period. The NOE’s for the Pittsburgh No. 8 Argonne Premium Coal Sample (APCS) before and after treatment with chlorobenzene’ have been determined by comparing the peak intensities in the normal and NOE-enhanced SPE spectra obtained with the same number of scans (800 or 1000). For purposes of comparison, NOE measurements have also been carried out on adamantane, hexamethylbenzene, and a highly cross-linked divinylbenzene/styrene (DVB/S) copolymer. All the SPE experiments were carried out on a Bruker MSLlOO spectrometer with magic-angle spinning at 5 kHz as described previously.8 The spectra of the coal samples were obtained using recycle delays of 60 and 200 s, with the 1H pulse train being applied for varying periods. Dipolar dephased (DD) SPE spectra were obtained in the

To investigate the properties of a pure liquid ordered (Lo) phase in a model membrane system, a series of saturated phosphatidylcholines combined with cholesterol were examined by variable temperature multinuclear (1H, 2H, 13C, 31P) solid-state NMR spectroscopy and x-ray scattering. Compositions with cholesterol concentrations ≥40mol %, well within the Lo phase region, are shown to exhibit changes in properties as a function of temperature and cholesterol content. The 2H-NMR data of both cholesterol and phospholipids were used to more accurately map the Lo phase boundary. It has been established that the gel-Lo phase coexistence extends to 60mol % cholesterol and a modified phase diagram is presented. Combined 1H-, 2H-, 13C-NMR, and x-ray scattering data indicate that there are large changes within the Lo phase region, in particular, 1H-magic angle spinning NMR and wide-angle x-ray scattering were used to examine the in-plane intermolecular spacing, which approaches that of a fluid Lα phase at high temperature and high cholesterol concentrations. Although it is well known for cholesterol to broaden the gel-to-fluid transition temperature, we have observed, from the 13C magic angle spinning NMR data, that the glycerol region can still undergo a “melting”, though this is broadened with increasing cholesterol content and changes with phospholipid chain length. Also from 2H-NMR order parameter data it was observed that the effect of temperature on chain length became smaller with increasing cholesterol content. Finally, from the cholesterol order parameter, it has been previously suggested that it is possible to determine the degree to which cholesterol associates with different phospholipids. However, we have found that by taking into account the relative temperature above the phase boundary this relationship may not be correct.

Strontium is one of the most common substituents in apatite crystals. The presence and behavior of Sr in apatite-group phases are of considerable significance in biology. The present paper investigates the substitution of strontium for calcium in a glass-ceramic of the following composition 4.5SiO23Al2O31.5P2O54CaO1CaF2. The glasses were characterized using Differential Thermal Analysis (DTA), X-ray powder diffraction (XRD), neutron diffraction (ND) and 19F Resonance Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). The all calcium glass crystallized to calcium fluorapatite (Ca5(PO4)3F). Substituting strontium partially for calcium resulted in the formation of a mixed strontium/calcium fluorapatites. In contrast complete substitution resulted in the formation of strontium fluorapatite. MAS-NMR showed the the F to be present as F-Ca(3) representing a fluoride ion surrounded by three Ca2+ ions in the all calcium glass and was present as F-Sr(3) in the all strontium glass. In the mixed glasses fluorine was present as FCa( 3), F-Ca(2)Sr, F-CaSr(2) and F-Sr(3). Ca had a higher tendency to occupy the F-M(3) sites than Sr which may reflect the higher charge to size ratio of Ca2+ relative to Sr2+ and its greater affinity for F- ions.