Biodegradable Normal Human Osteoblast (NHOst) cells were inoculated into the polymer scaffolds of poly(β-hydroxybutyrate) (PHB) obtained from a specially developed strain of Azotobacter vinelandii. Cell adhesion is essential to promote growth on scaffolds for tissue engineering. Thus, in this research we focused on the adhesion of osteoblast cells to PHB scaffolds produced by solution casting and electrospinning. Cell viability was also investigated up to 168 hrs. Water contact angle on the PHB scaffolds was determined prior to the cells inoculation. The contact angle is usually related to the ability of different cell strains to adhere to a given material. The as cast film exhibited a contact angle α=72° whereas for the electrospun membrane α=102°, thus in theory cell adhesion would be greater for the cast film. Biological testing was carried out on plates of 24 wells; cell viability was determined by Trypan Blue, cell morphology by optical microscopy, and cell nuclei integrity by staining with Acridine orange. Parallel studies were carried out on control (empty) wells. Microscopy observations 168 hrs after cell inoculation showed larger quantities of osteoblast cells in the wells containing PHB scaffolds and the cell nuclei were still active. Moreover, it was found that the cells grew inside the PHB scaffolds and the cell viability was slightly greater for the electrospun scaffold. Interestingly, the time to remove the cells from the scaffolds (film and membranes) was increasing function of the cell culture time, therefore suggesting that PHB promotes adhesion of Normal Human Osteoblast cells to its surface.

Porous coatings at the surface of living cells have application in human cell transplantation by controlling the transport of biomolecules to and from the cells. Sol-gel-derived mesoporous silica materials are good candidates for such coatings, owing to their biocompatibility, facile solution-based synthesis conditions, and thin film formation. Diffusion and transport across the coating correlates to long-range microstructural properties, including pore size distribution, porosity, and pore morphology. Here, we investigated collagen-fibril matrices with known biocompatibility to serve as templating systems for directed silica deposition. Type 1 collagen oligomers derived from porcine skin are extensively characterized such that we can predict and customize the final collagen-fibril matrix with respect to fibril density, interfibril branching and viscoelasticity. We show that these matrices template and direct the deposition of mesoporous silica at the level of individual collagen fibrils. We varied the fibril density, silicic acid concentration, and time of exposure to silicifying solution and characterized the resulting hybrid materials by scanning electron microscopy, energy-dispersive x-ray spectroscopy, and rheology. Microstructural properties of the collagen-fibril template are preserved in the silica surface of hybrid materials. Results for three different collagen fibril densities, corresponding to shear storage moduli of 200 Pa, 1000 Pa, and 1600 Pa, indicate that increased fibril density increases the absolute amount of templated silica when all other silica synthesis conditions are kept constant. Additionally, mechanical properties of the hybrid material are dominated by the presence of the silica coating rather than the starting collagen matrix stiffness.

Single-crystalline rutile with porous and complex structure can be produced by tuning reaction conditions so as to maintain low titania solubility. X-ray diffraction, high-resolution transmission electron microscopy, and cryogenic transmission electron microscopy results are consistent with the hypothesis that oriented aggregation of anatase crystals precedes rutile nucleation and growth from anatase nanocrystal interfaces. The product rutile retains morphological and microstructure features consistent with an aggregation-based phase transformation because coarsening, or monomer-by-monomer growth, is suppressed under these conditions of low titania solubility.

Mechanical properties and new morphological data on synthetic sodium hydrogen urate monohydrate are reported and interpreted. Crystals formed in supersaturated aqueous solutions were identified by powder x-ray diffraction. Intact grains and separate needles were examined by several microscopy techniques, some reported here for the first time. The dominant morphology was spherulite-type, comprising tapered, branched blades (needles) radiating out of a common core. The pointed blade tips were truncated by (011) planes, corresponding to hydrogen-bonded planes. Branching was at about a 5° angle or its multiples, suggesting it accommodated by dislocation arrays at the low angle boundaries, as is often seen in twinning. Vicker’s micro-hardness, extrapolated to zero porosity, was 0.90 GPa, which is greater than the hardness measured by nano-indentation. Present results are anticipated to be useful in interpreting the mechanical characteristics of the material crystallized in vivo and its action concerning gout, and affording inferences on the role of the milieu on morphologies, fragmentation, and hardness.