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Blood glucose supplies energy to cells and is critical for the human brain. Glycation of collagen, the nonenzymatic formation of glucose-bridges, relates to diseases of aging populations and diabetics. This chemical reaction, together with its biomechanical effects, has been well studied employing animal models. However, the direct impact of glycation on collagen nano-structure is largely overlooked, and there is a lack of ex vivo model systems. Here, we present the impact of glucose on collagen nanostructure in a model system based on abundantly available connective tissue of farm animals. By combining ex vivo small and wide-angle X-ray scattering (SAXS/WAXS) imaging, we characterize intra- and inter-molecular parameters of collagen in decellularized bovine pericardium with picometer precision. We observe three distinct regimes according to glucose concentration. Such a study opens new avenues for inspecting the effects of diabetes mellitus on connective tissues and the influence of therapies on the resulting secondary disorders., (© 2019 The Authors. Journal of Biophotonics published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The hierarchical structure of bone makes the X-ray microdiffraction scanning techniques one of the most effective tool to investigate the structural features of this tissue at different length scales: the atomic/nanometer scale of the X-ray scattering signals and the macroscopic scale of the scanned sample area. The potentiality of the microdiffraction approach has been verified also by investigations on tissue-engineered bone substitutes used to repair large hard bone defects. The aim of this review is to present the most representative and recent results obtained through high-resolution scanning microdiffraction techniques studying both natural and tissue-engineered bone. The rapid evolution of the instrumental set-ups and the advanced methods of data analysis are described. Recent examples in which X-ray microbeams were used for imaging quantitative features of natural bone tissue and engineered bone substitutes are presented along with the qualitative and quantitative information extracted from the two-dimensional patterns collected on bone samples and on ex vivo cell seeded bioceramic implants. Thanks to the microdiffraction approach, several aspects of the mechanisms leading to the generation of the new bone, coupled to the scaffold resorption in the tissue-engineered constructs, have been tentatively interpreted. The potential of X-ray microdiffraction as an imaging tool in the field of bone tissue engineering is discussed and the key role of high-spatial resolution, availability of automatic tools (for dealing with the huge amount of experimental data) and advanced analysis techniques is elucidated. Finally, future perspectives in the field are presented.

The challenge of fine compositional tuning and microstructure control in complex oxides is overcome by developing a general two-step synthetic approach. Antimony-alloyed bismuth vanadate, which is identified as a novel light absorber for solar fuel applications, is prepared in a wide compositional range. The bandgap of this quaternary oxide linearly decreases with the Sb content, in agreement with first-principles calculations.

Provides information on a study which derived a second-order approximation of the incidence parameter in an arbitrary lattice deformation to determine the strain field of highly mismatched semiconductor heterostructures. Lattice strain and chemical composition of semiconductor heterostructures; Use of x-ray diffraction.

During recent decades innovative nanomaterials have been extensively studied, aiming at both investigating the structure-property relationship and discovering new properties, in order to achieve relevant improvements in current state-of-the art materials. Lately, controlled growth and/or assembly of nanostructures into hierarchical and complex architectures have played a key role in engineering novel functionalized materials. Since the structural characterization of such materials is a fundamental step, here we discuss X-ray scattering/diffraction techniques to analyze inorganic nanomaterials under different conditions: dispersed in solutions, dried in powders, embedded in matrix, and deposited onto surfaces or underneath them. [ABSTRACT FROM AUTHOR]

In this paper, a method to synthesize anatase TiO2 nanorods by hydrolysis of titanium(IV) isopropoxide (TTIP) in the presence of benzyl alcohol and acetic acid at 210 °C was tested. The novelty of the present approach relies on the evaluation of the shape-controlled synthesis of anatase TiO2 nanocrystals via a microwave-solvothermal method in 45 min. The different TiO2 nanocrystals were obtained by tuning the TTIP/acetic acid ratio under optimized synthetic conditions and were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), micro Raman (together with microphotoluminescence) and FT-IR spectroscopies. The acetic acid coordinated on the nanocrystal surface was removed by the reduction of its carboxyl group via a "super-hydride reaction", and the photocatalytic activity of bare TiO2 nanocrystals, under visible light irradiation, was also evaluated: the best performing TiO2 anatase nanocrystals exhibited a discrete photoactivity, completely degrading Rhodamine B solution in five hours. [ABSTRACT FROM AUTHOR]

The nanoscale structural order of air-dried rat-tail tendon is investigated using small-angle X-ray scattering (SAXS). SAXS fiber diffraction patterns were collected with a superbright laboratory microsource at XMI-LAB [Altamura, Lassandro, Vittoria, De Caro, Siliqi, Ladisa & Giannini (2012). J. Appl. Cryst. 45, 869-873] for increasing integration times (up to 10 h) and a novel algorithm was used to estimate and subtract background, and to deconvolve the beam-divergence effects. Once the algorithm is applied, the peak visibility improves considerably and reciprocal space information up to the 22nd diffraction order is retrieved ( q = 0.21 Å−1, d = 29 Å) for an 8-10 h integration time. The gain in the visibility is already significant for patterns collected for 0.5 h, at least on the more intense peaks. This demonstrates the viability of detecting structural changes on a molecular/nanoscale level in tissues with state-of-the-art laboratory sources and also the technical feasibility to adopt SAXS fiber diffraction as a future potential clinical indicator for disease. [ABSTRACT FROM AUTHOR]

The properties of nanoscale materials vary with the size and shape of the building blocks, which can be measured by (grazing-incidence) small-angle X-ray scattering along with the mutual positions of the nanoparticles. The accuracy in the determination of such parameters is dependent on the signal-to-noise ratio of the X-ray scattering pattern and on the visibility of the interference fringes. Here, a first-generation-synchrotron-class X-ray laboratory microsource was used in combination with a new restoration algorithm to probe nanoscale-assembled superstructures. The proposed algorithm, based on a maximum likelihood approach, allows one to deconvolve the beam-divergence effects from data and to restore, at least partially, missing data cut away by the beam stopper. It is shown that the combination of a superbright X-ray laboratory microsource with the data-restoring method allows a virtual enhancement of the instrument brilliance, improving signal-to-noise ratio and fringe visibility and reaching levels of performance comparable to third-generation synchrotron radiation beamlines. [ABSTRACT FROM AUTHOR]

Electron diffractive imaging (EDI) relies on combining information from the high-resolution transmission electron microscopy image of an isolated kinematically diffracting nano-particle with the corresponding nano-electron diffraction pattern. Phase-retrieval algorithms allow one to derive the phase, lost in the acquisition of the diffraction pattern, to visualize the actual atomic projected potential within the specimen at sub-ångström resolution, overcoming limitations due to the electron lens aberrations. Here the approach is generalized to study extended crystalline specimens. The new technique has been called keyhole electron diffractive imaging (KEDI) because it aims to investigate nano-regions of extended specimens at sub-ångström resolution by properly confining the illuminated area. Some basic issues of retrieving phase information from the EDI/KEDI measured diffracted amplitudes are discussed. By using the generalized Shannon sampling theorem it is shown that whenever suitable oversampling conditions are satisfied, EDI/KEDI diffraction patterns can contain enough information to lead to reliable phase retrieval of the unknown specimen electrostatic potential. Hence, the KEDI method has been demonstrated by simulations and experiments performed on an Si crystal cross section in the [112] zone-axis orientation, achieving a resolution of 71 pm. [ABSTRACT FROM AUTHOR]

A new procedure aimed at unfolding a two-dimensional powder diffraction image into both a one-dimensional azimuthal and a radial scan is presented. In this approach, the sample-to-detector distance is the only parameter that must be adjusted in a separate step by using a standard sample. The technique consists of three steps: tracking the beam centre as the local maximum of the self-convolution of the original two-dimensional map, detector tilt and rotation determination by an intensity-tensor diagonalization, and azimuthal/radial intensity integration by a conformal mapping of the original two-dimensional powder diffraction image. The X-ray powder diffraction (XRPD) intensity profile of the NIST Si 640c standard sample is used to test the performance. The results show the robustness of the method and its capability of efficiently tagging the pixels in a two-dimensional readout system by matching the ideal geometry of the detector to the real beam-sample-detector frame. The technique is a fast, versatile and user-friendly tool for the simultaneous analysis of both azimuthal and radial spectra of two-dimensional XRPD images. [ABSTRACT FROM AUTHOR]

A novel synthesis of CdSe nanocrystals is presented, which is based on the room temperature reaction between selenourea and cadmium nitrate triggered by the fast injection of a base. A long-chain thiol was employed for terminating the aggregation of the species created by the reaction, obtaining monodispersed particles that were heat-treated in pyridine at 145 °C to grow larger particles. TEM observations and optical absorption spectra indicate that the particle size depends on the synthesis parameters, while XRD shows the formation of CdSe nanocrystals with hexagonal crystal system. The analysis of the optical absorption spectra allows proposing a first, simple model for the formation and growth of the nanocrystals. The reaction mechanism seems to proceed through the formation of a cadmium–selenourea intermediate species. [Copyright &y& Elsevier]

The surface and structural characterization techniques of three atom-thick bi-dimensional 2D-WS2 colloidal nanocrystals cross the limit of bulk investigation, offering the possibility of simultaneous phase identification, structural-to-morphological evaluation, and surface chemical description. In the present study, we report a rational understanding based on X-ray photoelectron spectroscopy (XPS) and structural inspection of two kinds of dimensionally controllable 2D-WS2 colloidal nanoflakes (NFLs) generated with a surfactant assisted non-hydrolytic route. The qualitative and quantitative determination of 1T' and 2H phases based on W 4f XPS signal components, together with the presence of two kinds of sulfur ions, S22− and S2−, based on S 2p signal and related to the formation of WS2 and WOxSy in a mixed oxygen-sulfur environment, are carefully reported and discussed for both nanocrystals breeds. The XPS results are used as an input for detailed X-ray Diffraction (XRD) analysis allowing for a clear discrimination of NFLs crystal habit, and an estimation of the exact number of atomic monolayers composing the 2D-WS2 nanocrystalline samples. [ABSTRACT FROM AUTHOR]

The paper focuses on the development of electron coherent diffraction imaging in transmission electron microscopy, made in the, approximately, last ten years in our collaborative research group, to study the properties of materials at atomic resolution, overcoming the limitations due to the aberrations of the electron lenses and obtaining atomic resolution images, in which the distribution of the maxima is directly related to the specimen atomic potentials projected onto the microscope image detector. Here, it is shown how augmented coherent diffraction imaging makes it possible to achieve quantitative atomic resolution maps of the specimen atomic species, even in the presence of low atomic number atoms within a crystal matrix containing heavy atoms. This aim is achieved by: (i) tailoring the experimental set-up, (ii) improving the experimental data by properly treating parasitic diffused intensities to maximize the measure of the significant information, (iii) developing efficient methods to merge the information acquired in both direct and reciprocal spaces, (iv) treating the dynamical diffused intensities to accurately measure the specimen projected potentials, (v) improving the phase retrieval algorithms to better explore the space of solutions. Finally, some of the future perspectives of coherent diffraction imaging in a transmission electron microscope are given. [ABSTRACT FROM AUTHOR]

Abstract: The Debye Function Analysis of diffraction patterns from nanosized mineral crystals showing different average degrees of maturity was carried out on engineered bone samples. The analysis relied on a bivariate family of atomistic hydroxyapatite nanocrystal models and provided information about crystal structure, size and shape distributions of the mineral component of the newly formed bone. An average rod-like shape of nanocrystals was found in all samples, with average sizes well matching the collagen I gap region. The diffraction patterns investigated through the Debye Function Analysis were used as signal models to perform the Canonical Correlation Analysis of high resolution X-ray micro-diffraction patterns collected on porous and resorbable hydroxyapatite/silicon-stabilized tricalcium phosphate (Si-TCP) implants. The nosologic maps clearly showed a size gradient in the new formed bone that validates the mechanism (mimicking the bone remodelling in orthotopic bones) of a continuous deposition of bone by osteoblasts, an increasing mineralization of the newly deposited bone, a growth of the new crystals, at the same time that osteoclasts adhere to the scaffold surface and resorb the bioceramic. The comparison of samples at different implantation times proved that the selective resorption of Si-TCP component from the scaffold was already evident after two and almost complete after six months. [ABSTRACT FROM AUTHOR]

Nanocrystal superlattices are attracting significantinterest dueto novel and peculiar collective properties arising from the interactionsof the nanocrystals forming the superlattice. A large variety of superlatticestructures can be obtained, involving one or more types of nanocrystals,with different sizes and concentrations. Engineering of the superlatticeproperties relies on accurate structural and morphological characterization,able to provide not only a fundamental feedback for synthesis procedures,but also relevant insight into their structural properties for possibleapplications. Electron microscopy and X-ray based techniques are complementaryapproaches for nanoscale structural imaging, which however becomechallenging in the presence of building blocks only a few nanometersin size. Here, a structure solution for a three-dimensional (3D) self-assemblyof PbS nanocrystals with bimodal size distribution is obtained, byexploiting small-angle X-ray diffraction, transmission electron microscopy,crystallographic procedures, and geometric constraints. In particular,analysis of small-angle X-ray diffraction data, based on the Pattersonfunction and on the single crystal model, is shown to provide relevantinformation on the 3D superlattice structure as well as on particlesize, the scattering signal being sensitive to particles as smallas 1.5 nm. The combined approach here proposed is thus demonstratedto effectively overcome important resolution limitations in the imagingof superlattices including small nanocrystals. [ABSTRACT FROM AUTHOR]

We report the synthesis, the structural and optical characterization of CdSe/CdS/ZnS double shell" nanorods and their exploitation in cell labeling experiments. To synthesize such nanorods, first "dot- in-a-rod" CdSe(dot)/CdS(rod) core/shell nanocrystals were prepared. Then a ZnS shell was grown epitaxially over these CdSe/CdS nanorods, which led to a fluorescence quantum yield of the final core-shell-shell nanorods that could be as high as 75%. The quantum efficiency was correlated with the aspect ratio of the nanorods and with the thickness of the ZnS shell around the starting CdSe/CdS rods, which varied from 1 to 4 monolayers (as supported by a combination of X-ray diffraction, elemental analysis with inductively coupled plasma atomic emission spectroscopy and high resolution transmission electron microscopy analysis). Pump-probe and time-resolved photoluminescence measurements confirmed the reduction of trapping at CdS surface due to the presence of the ZnS shell, which resulted in more efficient photoluminescence. These double shell nanorods have potential applications as fluorescent biological labels, as we found that they are brighter in cell imaging as compared to the.starting CdSe/CdS nanorods and to the CdSe/ZnS quantum dots, therefore a lower amount of material is required to label the cells. Concerning their cytotoxicity, according to the MIT assay, the double shell nanorods were less toxic than the starting core/shell nanorods and than the CdSe/ZnS quantum dots, although the latter still exhibited a lower intracellular toxicity than both nanorod samples. [ABSTRACT FROM AUTHOR]