Comparative Characterisation of 3-D Hydroxyapatite Scaffolds Developed via Replication of Synthetic Polymer Foams and Natural Marine Sponges

The production of complex inorganic forms, based on naturally occurring scaffolds offers an exciting avenue for the construction of a new generation of ceramic-based bone substitute scaffolds. The following study reports an investigation into the architecture (porosity, pore size distribution, pore interconnectivity and permeability), mechanical properties and cytotoxic response of hydroxyapatite bone substitutes produced using synthetic polymer foam and natural marine sponge performs. Infiltration of polyurethane foam (60 pores/in2) using a high solid content (80wt %), low viscosity (0.126Pas) hydroxyapatite slurry yielded 84-91% porous replica scaffolds with pore sizes ranging from 50µm - 1000µm (average pore size 577µm), 99.99% pore interconnectivity and a permeability value of 46.4 x10-10m2. Infiltration of the natural marine sponge, Spongia agaricina, yielded scaffolds with 56- 61% porosity, with 40% of pores between 0-50µm, 60% of pores between 50-500µm (average pore size 349 µm), 99.9% pore interconnectivity and a permeability value of 16.8 x10-10m2. The average compressive strengths and compressive moduli of the natural polymer foam and marine sponge replicas were 2.46±1.43MPa/0.099±0.014GPa and 8.4±0.83MPa /0.16±0.016GPa respectively. Cytotoxic response proved encouraging for the HA Spongia agaricina scaffolds; after 7 days in culture medium the scaffolds exhibited endothelial cells (HUVEC and HDMEC) and osteoblast (MG63) attachment, proliferation on the scaffold surface and penetration into the pores. It is proposed that the use of Spongia agaricina as a precursor material allows for the reliable and repeatable production of ceramic-based 3-D tissue engineered scaffolds exhibiting the desired architectural and mechanical characteristics for use as a bone 3 scaffold material. Moreover, the Spongia agaricina scaffolds produced exhibit no adverse cytotoxic response.

Synthesis of spherical ultra-high-surface-area monodisperse amphipathic polymer sponges in the low-micrometer size range

Spherical, ultra-high specific surface area monodisperse polymer particles with diameters in the low micrometer size range are disclosed for the first time. The polymer particles are able to sorb significant levels of both hydrocarbon solvents and water, acting in effect as amphipathic micro-sponges. Exciting possibilities for exploitation of the particles in chromatography, diagnostics, sensors, delivery vehicles and catalysis are suggested.

Excavating the Brochtorff-Xaghra Circle, Gozo,

Malone, C. and S. Stoddart (with Vella Gregory, I. ). In prep. 2013. Midsea Books. Valletta: Midsea.

Mapping worlds? Excavating cartographic encounters in Plantation Ireland through GIS

This paper uses the analytical potential of Geographical Information Systems (GIS) to explore processes of map production and circulation in early-seventeenth century Ireland. The paper focuses on a group of historic maps, attributed to Josias Bodley, which were commissioned in 1609 by the English Crown to assist in the Plantation of Ulster. Through GIS and digitizing map-features, and in particular by quantifying map-distortion, it is possible to examine how these maps were made, and by whom. Statistical analyses of spatial data derived from the GIS are shown to provide a methodological basis for ‘excavating’ historical geographies of Plantation map-making. These techniques, when combined with contemporary written sources, reveal further insight on the ‘cartographic encounters’ taking place between surveyors and map-makers working in Ireland in the early 1600s, opening up the ‘mapping worlds’ which linked Ireland and Britain through the networks and embodied practices of Bodley and his map-makers.

Osteogenic cell response to 3-D hydroxyapatite scaffolds developed via replication of natural marine sponges

Bone tissue engineering may provide an alternative to autograft, however scaffold optimisation is required to maximize bone ingrowth. In designing scaffolds, pore architecture is important and there is evidence that cells prefer a degree of non-uniformity. The aim of this study was to compare scaffolds derived from a natural porous marine sponge (Spongia agaricina) with unique architecture to those derived from a synthetic polyurethane foam. Hydroxyapatite scaffolds of 1 cm3 were prepared via ceramic infiltration of a marine sponge and a polyurethane (PU) foam. Human foetal osteoblasts (hFOB) were seeded at 1x105 cells/scaffold for up to 14 days. Cytotoxicity, cell number, morphology and differentiation were investigated. PU-derived scaffolds had 84-91% porosity and 99.99% pore interconnectivity. In comparison marine sponge-derived scaffolds had 56-61% porosity and 99.9% pore interconnectivity. hFOB studies showed that a greater number of cells were found on marine sponge-derived scaffolds at than on the PU scaffold but there was no significant difference in cell differentiation. X-ray diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS) showed that Si ions were released from the marine-derived scaffold. In summary, three dimensional porous constructs have been manufactured that support cell attachment, proliferation and differentiation but significantly more cells were seen on marine-derived scaffolds. This could be due both to the chemistry and pore architecture of the scaffolds with an additional biological stimulus from presence of Si ions. Further in vivo tests in orthotopic models are required but this marine-derived scaffold shows promise for applications in bone tissue engineering.

Excavating a fossilized tree that is now in front of Hashinger Hall

Excavating a fossilized tree, which was later placed in front of Hashinger Hall, Chapman University, 346 N. Center Street, Orange, California. The late Dr. Edward H. Hashinger, former trustee and past chairman of the board is the man whose name has graced the walls of this building since 1969. The Hashinger Science Center (3 floors, 65,364 sq.ft.) houses all science departments including biology, natural and applied sciences, environmental and chemical sciences, food science and nutrition, kinesiology and physical therapy.

A journey through time : excavating life on earth.

Los secretos del pasado de nuetro planeta se esconden en las capas superpuestas y profundas que existen debajo de nuestros pies. Se puede vislumbrar la historia de nuestro planeta cuando las excavaciones arqueológicas desentierran restos del pasado de la Tierra : desde objetos de bronce encontrados en tumbas antiguas hasta animales y plantas fosilizados.