Sol-gel based materials for biomedical applications

Sol-gel chemistry offers a flexible approach to obtaining a diverse range of materials. It allows differing chemistries to be achieved as well as offering the ability to produce a wide range of nano-/micro-structures. The paper commences with a generalized description of the various sol-gel methods available and how these chemistries control the bulk properties of the end products. Following this, a more detailed description of the biomedical areas where sol-gel materials have been explored and found to hold significant potential. One of the interesting fields that has been developed recently relates to hybrid materials that utilize sol-gel chemistry to achieve unusual composite properties. Another intriguing feature of sol-gels is the unusual morphologies that are achievable at the micro- and nano-scale. Subsequently the ability to control pore chemistry at a number of different length scales and geometries has proven to be a fruitful area of exploitation, that provides excellent bioactivity and attracts cellular responses as well as enables the entrapment of biologically active molecules and their controllable release for therapeutic action. The approaches of fine-tuning surface chemistry and the combination with other nanomaterials have also enabled targeting of specific cell and tissue types for drug delivery with imaging capacity

Zinc and Strontium based Phosphate glass beads: a novel material for bone tissue engineering

Degradable phosphate-based glasses that contain strontium, zinc and calcium were investigated to examine its function as an osteoconductive material. Glass beads of the general formula of (P2O5)-(Na2O)-(TiO2)-(CaO)-(SrO) or (ZnO) were prepared by melt quench technique followed by milling and spheroidisation. Glass bead size distribution was initially measured by SEM. Then, some of these samples were immersed in deionized water to evaluate both the surface changes and measure the ion release rate, whereas other glass beads samples were incubated in culture media to determine pH changes. Furthermore, human osteoblast-like osteosarcoma cells MG-63 and human mesenchymal stem cells were seeded on the glass beads to determine its cytocompatibility via applying CCK assay, ALP assay and Ca assay. SEM images and fluorescence images of confocal microscopy were performed for the cellular studies. While mass degradation and ion release results displayed a significant increase with zinc and strontium incorporation within time, pH results showed an initial increase in pH followed by a decrease. Cellular studies emphasised that all formulations enhanced cellular proliferation. More specifically, ZnO5 and SrO17.5 displayed more promising results although they were insignificantly different from that of control (p>0.05). This may suggest their applicability in hard tissue engineering

Geophysical evidences on reactivation of NE faults in southern Arabian Shield and its tectonic implications

The Eastern flank of the Red sea represents an uplifted Precambrian basement that is known as the Arabian Shield. Different tectonic events were activated since the collisions among continental fragments that occurred during the period 630–550 Ma, showing very old NE ophiolite-suture zones, North trend shear zones, belts, folds, and NW Sinistral fault system known as Najd shear zones. Thus, heterogeneities and inherited faults are expected in the old basement; however, based on surface observations, NE trend faults are not described in the Arabian Shield. Despite the inconsistency with the background tectonic model of the Red Sea rifting, recent seismological studies show that active NE faults may exist in western Arabian Shield. This study aims to investigate and map the fault system in southern Arabian Shield and then better understand the tectonic system acting in the region. We provide an analysis that incorporates gravity, magnetic, and seismological data in Namas area, where earthquake sequence occurred in 2017. Using the regional-residual separation, filtering and edge detector function techniques, we identified NE trend inherited faults within the Precambrian basement that might be seismically active, as shown by the obtained distribution of epicenters and focal mechanism solutions of strike-slip style among the 2017 Namas Earthquake sequence. This result emphasizes the preexistence of a potential local tectonic process that is incongruous with the regional stress regime