The macro- and micro-features of bone can be assessed by using imaging methods. However, nano- and molecular features require more detailed characterization, such as use of e.g., vibrational spectroscopy and X-ray scattering. Nano- and molecular features also affect the mechanical competence of bone tissue. The aim of the present study was to reveal the effects of mineralization and its alterations on the mineral crystal scale, by investigating the spatial variation of molecular composition and mineral crystal structure across the cross-section of femur diaphyses in young rats, and healthy and osteoporotic mature rats (N=5). Fourier transform infrared spectroscopy and scanning small- and wide-angle X-ray scattering (SAXS/WAXS) techniques with high spatial resolution were used at identical locations over the whole cross-section. This allowed quantification of point-by-point information about the spatial distribution of mineral crystal volume. All measured parameters (crystal dimensions, degree of orientation and predominant orientation) varied across the cortex. Specifically, the crystal dimensions were lower in the central cortex than in the endosteal and periosteal regions. Mineral crystal orientation followed the cortical circumference in the periosteal and endosteal regions, but was less well-oriented in the central regions. Central cortex is formed rapidly during development through endochondral ossification. Since rats possess no osteonal remodeling, this bone remains (until old age). Significant linear correlations were observed between the dimensional and organizational parameters, e.g., between crystal length and degree of orientation (R(2)=0.83, p<0.001). Application of SAXS/WAXS provides valuable information on bone nanostructure and its constituents, effects of diseases and, prospectively, mechanical competence.

A section of the composition–temperature phase prism of a ternary non-ionic surfactant–water–oil system defined by a constant surfactant to oil ratio has been investigated. The structural sequence of normal spheres to planar bilayers, via cylinders, is observed as a function of decreasing water concentration at fixed temperature. As a function of increasing temperature at fixed surfactant and oil concentration, we note the commonly observed reversal in mean curvature of the polar/apolar interface. The mean curvature progressively alters from positive values in the low-temperature microemulsion phase to negative mean curvature in the high-temperature L₃ phase, with an intermediate lamellar phase where the mean curvature passes through zero. The phase diagram of this section is similar to that of the binary surfactant–water system. The average area per surfactant at the polar/apolar interface is 46 ± 2 Ų. A micellar cubic phase is observed between the microemulsion and the hexagonal phase while no bicontinuous cubic phase is observed.

Ostwald ripening of crystalline and amorphous nanoparticle dispersions of a model organic compound are compared.

Poly(ethylene glycol) (PEG) polymers and PEG-conjugated lipids are widely used in bioengineering and drug transport applications. A PEG layer in a drug carrier increases hydrophilic repulsion, inhibits membrane fusion and serum opsonin interactions, and prolongs the storage and circulation time. It can also change the carrier shape and have an influence on many properties related to content release of the carrier. In this paper, we focus on the physicochemical effects of PEGylation in the lipid bilayer. We introduce laurdanC as a fluorophore for the shape recognition and phase transition detection. Together with laurdanC, cryo-TEM, DSC, molecular dynamics (MD) simulations, and SAXS/WAXS, we acquire information of the particle/bilayer morphology and phase behavior in systems containing DPPC:DSPE-PEG(2000) with different fractions. We find that the PEGylation leads to two important and potentially usable features of the system: 1) spherical vesicles present a window of elevated chain melting temperatures and 2) lipid packing shape controlled liposome-to-bicelle transition. The first finding is significant for targets requiring multiple release sequences and the second enables tuning the release by composition and PEG polymer length. Besides drug delivery systems, the findings can be used in other smart soft materials with trigger-polymers as well.