Ana Labrador

The yellow mini-hutch for SAXS experiments at MAX IV Laboratory

I911-SAXS is the new SAXS (Small-Angle-X-ray-Scattering) beamline at the MAX IV Laboratory in Lund, Sweden. It is one of the 5 stations of the hard X-ray Cassiopeia beamline (I911) at the 1.5 GeV ring MAX II. I911-4 was converted into a multipurpose SAXS station which opened to the scientific community in May 2011. The SAXS users community at this laboratory comes from diverse fields of research with different needs and requirements at the end-station. This results in different set-ups routinely being installed in the easy-accessible experimental mini-hutch. The beam can be focused at sample-to-detector distances between a few hundred millimetres and more than two meters. This versatility permits a selection of q-ranges between 0.006 A−1 and 2 A−1. The recent acquisition of a fast readout, low noise pixel detector (PILATUS 1M) and the implementation of a hight-throughput solution SAXS are the latest beamline upgrades.

The macromolecular crystallography beamline I911-3 at the MAX IV laboratory

The updated macromolecular crystallography beamline I911-3 at the MAX II storage ring is described.

Low-Dimensional Copper(II) Complexes with the Trinucleating Ligand 2,4,6-Tris(di-2-pyridylamine)-1,3,5-triazine: Synthesis, Crystal Structures, and Magnetic Properties†

The preparation and structural characterization of three new copper(II) complexes of formula [Cu(3)(dipyatriz)(2)(H(2)O)(3)](ClO(4))(6) x 2 H(2)O (1), {[Cu(4)(dipyatriz)(2)(H(2)O)(2)(NO(3))(2)(ox)(2)](NO(3))(2) x 2 H(2)O}(n) (2), and [Cu(6)(dipyatriz)(2)(H(2)O)(9)(NO(3))(3)(ox)(3)](NO(3))(3) x 4 H(2)O (3) [dipyatriz = 2,4,6-tris(di-2-pyridylamine)-1,3,5-triazine and ox = oxalate] are reported. The structure of 1 consists of trinuclear units [Cu(3)(dipyatriz)(2)(H(2)O)(3)](6+) and uncoordinated perchlorate anions. The two dipyatriz molecules in 1 act as tris-bidentate ligands with the triazine cores being in a quasi eclipsed conformation. Each copper atom in 1 exhibits a distorted square pyramidal geometry CuN(4)O with four pyridyl-nitrogen atoms from two dipyatriz ligands building the basal plane and a water molecule occupying the axial position. The values of the intratrimer copper-copper separation are 8.0755(6) and 8.3598(8) A. Compound 2 exhibits a layered structure of copper(II) ions which are connected through bis-bidentate dipyatriz ligands and bidentate/outer monodentate oxalato groups. The copper atoms in 2 exhibit six- [Cu(1)N(4)O(2)] and five-coordination [Cu(2)N(2)O(3)]. A water molecule and three pyridyl-nitrogen atoms [Cu(1)] and two pyridyl-nitrogen plus two oxalate-oxygen atoms [Cu(2)] define the equatorial plane whereas either an oxalate-oxygen and a pyridyl-nitrogen [Cu(1)] or a nitrate-oxygen [Cu(2)] fill the axial positions. The copper-copper separation through the bridging oxalato is 5.6091(6) A whereas those across dipyatriz vary in the range 7.801(1)-9.079(1) A. The structure of compound 3 contains discrete cage-like hexacopper(II) units [Cu(6)(dipyatriz)(2)(H(2)O)(9)(NO(3))(3)(ox)(3)](3+) where two trinuclear [Cu(3)(dipyatriz)](6+) fragments are connected by three bis-bidentate oxalate ligands, the charge being balanced by three non-coordinated nitrate anions. The values of the intracage copper-copper distance are 5.112(3)-5.149(2) A (across oxalato) and 7.476(2)-8.098(2) A (through dipyatriz). Magnetic susceptibility measurements of polycrystalline samples of 1-3 in the temperature range 1.9-295 K show the occurrence of a weak antiferromagnetic interaction across dipyatriz in 1 [J = -0.08(1) cm(-1), the Hamiltonian being defined as (wedge)H = -J ((wedge)S(1).(wedge)S(2) + (wedge)S(1) x (wedge)S(3) + (wedge)S(2) x (wedge)S(3))] and weak ferro- (2) and strong antiferromagnetic (3) interactions through the oxalato bridge in 2 [J = +0.45(2) cm(-1)] and 3 [J = -390(1) cm(-1)]. The use of the dipyatriz-containing copper(II) species as a building block to design homo- and heterometallic magnetic compounds is analyzed and discussed.

The effect of lithium salt doping on the nanostructure of ionic liquids

In this work we report on the evolution of the structure of two model ionic liquid families, N-alkyl-N-methylpyrrolidinium (Pyr1n-TFSI) and 1-alkyl-3-methylimidazolium (CnMIm-TFSI) (n = 3, 4, 6 and 8) both containing the bis(trifluoromethanesulfonyl)imide (TFSI) anion, upon the addition of LiTFSI using small angle X-ray scattering (SAXS). The introduction of a lithium salt (Li-salt) tunes the interactions through the substitution of the large cation in the ionic liquid with the small and charge localized lithium ion, thus increasing the coulombic contribution from ion-ion interactions. We find that the introduction of lithium ions results in a restructuring of the polar groups in the ionic liquids. These changes are manifested as an increase in the correlation lengths related to charge alternation of the ions and a more disordered structure. This restructuring is interpreted as a reconfiguration of the anions as they coordinate to the small and ionic lithium. In contrast, the length scale of the mesoscopic heterogeneities related to the clustering of alkyl chains is virtually unchanged with lithium doping. Moreover, the correlation corresponding to alkyl chain domains becomes more well defined with increasing salt concentration, suggesting that Li-salt doping, i.e. an increased columbic interaction in the system, promotes clustering of the alkyl tails.

Evaluation of composition and mineral structure of callus tissue in rat femoral fracture

Abstract. Callus formation is a critical step for successful fracture healing. Little is known about the molecular composition and mineral structure of the newly formed tissue in the callus. The aim was to evaluate the feasibility of small angle x-ray scattering (SAXS) to assess mineral structure of callus and cortical bone and if it could provide complementary information with the compositional analyses from Fourier transform infrared (FTIR) microspectroscopy. Femurs of 12 male Sprague–Dawley rats at 9 weeks of age were fractured and fixed with an intramedullary 1.1 mm K-wire. Fractures were treated with the combinations of bone morphogenetic protein-7 and/or zoledronate. Rats were sacrificed after 6 weeks and both femurs were prepared for FTIR and SAXS analysis. Significant differences were found in the molecular composition and mineral structure between the fracture callus, fracture cortex, and control cortex. The degree of mineralization, collagen maturity, and degree of orientation of the mineral plates were lower in the callus tissue than in the cortices. The results indicate the feasibility of SAXS in the investigation of mineral structure of bone fracture callus and provide complementary information with the composition analyzed with FTIR. Moreover, this study contributes to the limited FTIR and SAXS data in the field.

Capabilities of through-the-substrate microdiffraction: application of Patterson-function direct methods to synchrotron data from polished thin sections

Some theoretical and practical aspects of the application of transmission microdiffraction (µXRD) to thin sections (≤30 µm thickness) of samples fixed or deposited on substrates are discussed. The principal characteristic of this technique is that the analysed micro-sized region of the thin section is illuminated through the substrate (tts-µXRD). Fields that can benefit from this are mineralogy, petrology and materials sciences since they often require in situ lateral studies to follow the evolution of crystalline phases or to determine new crystal structures in the case of phase transitions. The capability of tts-µXRD for performing structural studies with synchrotron radiation is shown by two examples. The first example is a test case in which tts-µXRD intensity data of pure aerinite are processed using Patterson-function direct methods to directly solve the crystal structure. In the second example, tts-µXRD is used to study the transformation of laumonite into a new aluminosilicate for which a crystal structure model is proposed.

Direct monitoring of calcium-triggered phase transitions in cubosomes using small-angle X-ray scattering combined with microfluidics

This article introduces a simple microfluidic device that can be combined with synchrotron small-angle X-ray scattering (SAXS) for monitoring dynamic structural transitions. The microfluidic device is a thiol-ene-based system equipped with 125 μm-thick polystyrene windows, which are suitable for X-ray experiments. The device was prepared by soft lithography using elastomeric molds followed by a simple UV-initiated curing step to polymerize the chip material and simultaneously seal the device with the polystyrene windows. The microfluidic device was successfully used to explore the dynamics of the structural transitions of phytantriol/dioleoylphosphatidylglycerol-based cubosomes on exposure to a buffer containing calcium ions. The resulting SAXS data were resolved in the time frame between 0.5 and 5.5 s, and a calcium-triggered structural transition from an internal inverted-type cubic phase of symmetry Im3m to an internal inverted-type cubic phase of symmetry Pn3m was detected. The combination of microfluidics with X-ray techniques opens the door to the investigation of early dynamic structural transitions, which is not possible with conventional techniques such as glass flow cells. The combination of microfluidics with X-ray techniques can be used for investigating protein unfolding, for monitoring the formation of nanoparticles in real time, and for other biomedical and pharmaceutical investigations. A combination of microfluidics with X-ray techniques has been used to perform dynamic structural studies on nanoparticulate formulations. (Less)

Microfluidic Platform for the Continuous Production and Characterization of Multilamellar Vesicles: A Synchrotron Small-Angle X-ray Scattering (SAXS) Study

A microfluidic platform combined with synchrotron small-angle X-ray scattering (SAXS) was used for monitoring the continuous production of multilamellar vesicles (MLVs). Their production was fast and started to evolve within less than 0.43 s of contact between the lipids and the aqueous phase. To obtain nanoparticles with a narrow size distribution, it was important to use a modified hydrodynamic flow focusing (HFF) microfluidic device with narrower microchannels than those normally used for SAXS experiments. Monodispersed MLVs as small as 160 nm in size, with a polydispersity index (PDI) of approximately 0.15 were achieved. The nanoparticles produced were smaller and had a narrower size distribution than those obtained via conventional bulk mixing methods. This microfluidic platform therefore has a great potential for the continuous production of monodispersed NPs.

BioMAX: The Future Macromolecular Crystallography Beamline at MAX IV

This paper describes the preliminary design of the BioMAX beamline at the 3 GeV ring of the MAX IV facility, focusing on the optics and x-ray beam performance. The MAX IV facility will include two storage rings with 1.5 GeV and 3.0 GeV electron energy and a linac serving both as injector for the two rings and feeding a short pulse facility. BioMAX is one of the first seven beamlines funded at the MAX IV facility. It is a multipurpose high-throughput beamline for macromolecular crystallography. The beamline aims to be robust and simple to operate with a beam benefiting from the properties of the MAX IV 3 GeV ring. However it does not aim at the smallest beam or crystal sizes since it is foreseen that it will be complemented with a microfocus beamline aiming at a beam size of 1 mu m. The beamline experiment setup will be highly automated, both in terms of sample handling hardware and data analysis, including feedback to the data collection. The BioMAX beamline is planned to be in operation in 2016. (Less)

Using Curvature Power To Map the Domain of Inverse Micellar Cubic Phases: The Case of Aliphatic Aldehydes in 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine

Oxylipins, or fatty aldehydes, are a class of molecules produced from membrane lipids as a result of oxidative stress or enzyme-mediated peroxidation. Here we report the effects of two biologically important fatty aldehydes, trans,trans-2,4-decanedienal (DD) and cis-11-hexadecenal (HD), on the phase behavior of the lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) in water. We compare the phase behavior of DD/DOPE and HD/DOPE mixtures to the phase behavior of oleic acid/DOPE mixtures and show that DD, HD, and oleic acid have similar effects on the phase diagrams of DOPE. Notably, both DD and HD, like oleic acid, induce the formation of Fd3m inverse micellar cubic phases in DOPE/water mixtures. This is the first time that Fd3m phases in fatty aldehyde-containing mixtures have been reported. We assess the effects of DD, HD, and oleic acid on DOPE in terms of lipid spontaneous curvatures and propose a method to predict the formation of Fd3m phases from the curvature power of amphiphiles. This methodology predicts that Fd3m phases will become stable if the spontaneous curvature of a lipid mixture is -0.48 ± 0.05 nm-1 or less.