Bioactive glass-derived trabecular coating: a smart solution for enhancing osteointegration of prosthetic elements

In this work, the use of foam-like glass-ceramic scaffolds as trabecular coatings on ceramic prosthetic devices to enhance implant osteointegration is proposed. The feasibility of this innovative device was explored in a simplified, flat geometry: glass-ceramic scaffolds, prepared by polymeric sponge replication and mimicking the trabecular architecture of cancellous bone, were joined to alumina square substrates by a dense glass coating (interlayer). The role played by different formulations of starting glasses was examined, with particular care to the effect on the mechanical properties and bioactivity of the final coating. Microindentations at the coating/substrate interface and tensile tests were performed to evaluate the bonding strength between the sample's components. In vitro bioactive behaviour was assessed by soaking in simulated body fluid and evaluating the apatite formation on the surface and inside the pores of the trabecular coating. The concepts disclosed in the present study can have a significant impact in the field of implantable devices, suggesting a valuable alternative to traditional, often invasive bone-prosthesis fixatio

Subsurface life can modify volatile cycling on a planetary scale

The past decade of environmental microbiology has revealed that subsurface environments, both marine and continental, harbor one of the largest ecosystems of our planet, with diversity and biomass rivaling those of the surface. In addition, subsurface life has been recently shown to contribute significantly to the planet’s biogeochemistry, with microbial activity potentially playing an important role in controlling the flux and composition of volatiles recycled between the Earth’s surface and interior, which has broad implications for the search for life beyond our planet. Current efforts to discover extraterrestrial life are focused on planetary bodies with largely inhospitable surfaces, such as Mars, Venus, Europa, Titan, and Enceladus. In these locations, subsurface environments might provide niches of habitability, making the study of deep microbial life a priority for future astrobiological missions. Understanding how volatile elements are exchanged between planetary surfaces and interiors and the role of a subsurface biosphere in altering their composition and flux might provide a tractable target for defining planetary habitability and the detection of subsurface life forms.Fil: Giovanelli, D.. Università degli Studi di Napoli Federico II; Italia. Tokyo Institute of Technology; Japón. Rutgers University; Estados Unidos. Consiglio Nazionale delle Ricerche; Italia. Woods Hole Oceanographic Institution; Estados UnidosFil: Barry, P. H.. Woods Hole Oceanographic Institution; Estados UnidosFil: Bekaert, D. V.. Woods Hole Oceanographic Institution; Estados UnidosFil: Chiodi, Agostina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Cordone, A.. Università degli Studi di Napoli Federico II; ItaliaFil: Covone, G.. Università degli Studi di Napoli Federico II; Italia. Istituto Nazionale di Astrofisica; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Jessen, G.. Universidad Austral de Chile; ChileFil: Lloyd, K.. University of Tennessee; Estados UnidosFil: de Moor, J. M.. Universidad Nacional; Costa RicaFil: Morrison, S. M.. Carnegie Institution For Science; Estados UnidosFil: Schrenk, M. O.. Michigan State University; Estados UnidosFil: Vitale Brovarone, A.. Alma Mater Studiorum Universit`a Di Bologna; Italia. Sorbonne University; Francia. Museum National d’Histoire Naturelle; Franci

Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study

Magma-poor rifted margins are being increasingly recognized in present-day Atlantic-type systems. However, findings of fossil areas floored by exhumed mantle or hyper-extended crust are comparatively rare within orogenic belts that were originated through the inversion of pre-existing rifted margins. This discrepancy may be due to the common reactivation of lithological contacts during subduction/orogeny, potentially masking pre-orogenic relationships, and, most importantly, to the frequent lack of a pre- orogenic layer-cake architecture, hindering retro-deformation of multiply deformed tectonic units. This study outlines a methodology to detect sections of magma-poor, hyper-extended rifted margins without a layer-cake architecture in multiply deformed/metamorphosed terrains. This approach is defined by com- parison to well studied examples of fossil analogues preserved in weakly deformed parts of Alpine orogens. In the latter domains, continental basement and hydrated peridotites were exhumed at the basin floor dur- ing Jurassic rifting along long-offset detachment systems. Extensional geometries locally resulted in tecton- ic sampling of laterally discontinuous slivers of allochthonous continental basement and pre-rift sediments from the hanging wall blocks. Lithostratigraphic associations consisting of continental basement rocks direct- ly juxtaposed with syn- to post-rift meta-sediments and/or serpentinized subcontinental mantle are widespread within sections of Alpine-type orogenic belts that underwent high- to ultra-high-pressure metamorphism. However, similar associations may arise from a variety of processes other than rift-related lithospheric thinning in magma-poor environments, including subduction mélange dynamics or deposition of sedimentary mélanges along convergent/divergent margins. The partial preservation of rift-related lithostratigraphic associations may still be assessed, despite the lack of biostratigraphic evidence, by (1) the consistency of the lithostratigraphic archi- tecture over large areas, despite pervasive Alpine deformation, which rules out chaotic mixing during subduction/ exhumation, (2) the presence of clasts of basement rocks in the neighboring meta-sediments, indicating the orig- inal proximity of the different lithologies, (3) evidence of brittle deformation in continental basement and ultra- mafic rocks pre-dating Alpine metamorphism, indicating that they were juxtaposed by fault activity prior to the deposition of post-rift sediments, and (4) the similar Alpine tectono-metamorphic evolution of ophiolites, con- tinental basement and meta-sediments. A re-assessment of basement–cover relationships in the North-Western Alps following this approach, combined with published studies on exhumed mantle domains sampled in the rest of the Western Alps, indicates that sev- eral tectono-metamorphic units from the most deformed/metamorphosed part of the belt, between the Canavese Line and the Penninic Front, sample hyper-extended lithosphere related to the Jurassic opening of the Western Tethys. Relative plate motion during Cretaceous–Tertiary basin inversion was largely accommodated at the tran- sition between areas floored by hyper-extended crust or hydrated subcontinental mantle and domains consisting of thicker continental crust. As a result, distal margins were preferentially subducted, whereas the proximal domains and the Briançonnais paleo-high underwent relatively minor deformation and metamorphism. The high-pressure Alpine tectono-metamorphic units were probably detached from the downgoing lithosphere along a hydration front that is typically observed in present-day distal margins. The recognition of preserved pre-Alpine relationships between continental basement, post-rift sediments and/or serpentinized ultramafic rocks calls for a re-assessment of the relative role of subduction and rifting dynamics in establishing the present-day orogen architecture

Advanced Firmware and Hardware for Multiscale and Multimaterial Bioprinting

Bioprinting allows precise deposition of multiple materials at different scale lengths, to fabricate complex scaffolds which mimic the natural tissue cues. A novel trend in the design of 3D Bioprinters is the integration of multiple fabrication techniques into the same machine, to speed-up the scaffold fabrication process and increase the scaffold functionalities. Even if multi-technique bioprinters have reached the market, their implementation is far from being optimized. In this work we present a novel printing platform with high accuracy that implements two of the most commonly used Bioprinting strategies, namely piston-actuated extrusion and thermal drop-on-demand inkjet. Here we firstly present a method to find the optimal printing parameters, and then proof-of-concept printed shapes to validate the developed platform

Graphene Oxide Finely Tunes the Bioactivity and Drug Delivery of Mesoporous ZnO Scaffolds

Mesoporous zinc oxide (ZnO) scaffolds coated with drop-cast graphene oxide (GO) flakes are proposed to be a novel bilayer system featuring bioactivity, biocompatibility, and promising loading/release properties for controlled drug-delivery systems. The high-surface-area ZnO scaffolds show clear apatite deposition, but their particular surface chemistry and topography prevent the formation of a continuous coating, resulting in micrometric crystalline apatite aggregates after 28 days in simulated body fluid (SBF). When gentamicin sulfate (GS) is considered as a model molecule, pure ZnO scaffolds also show functional GS loading efficiency, with fast in vitro release kinetics driven by a simple diffusion mechanism. Strikingly, the bioactivity and GS delivery properties of mesoporous ZnO are efficiently triggered by drop-casting GO flakes atop the mesoporous scaffold surface. The resulting ZnO@GO bilayer scaffolds show the formation of a uniform apatite coating after 28 days in SBF and demonstrate a biocompatible behavior, supporting the culture of SaOS-2 osteoblast-like cells. Moreover, the GO coating also leads to a barrier-layer effect, preventing fast GS release, particularly in the short time range. This barrier effect, coupled with the existence of nanopores within the GO structure, sieves drug molecules from the mesoporous ZnO matrix and allows for a delayed release of the GS molecule. We, thus, demonstrated a new-generation ZnO@GO bilayer system as effective multifunctional and biocompatible scaffold for bone tissue engineering

Bioactivity and Mechanical Stability of 45S5 Bioactive Glass Scaffolds Based on Natural Marine Sponges

Bioactive glass (BG) based scaffolds (45S5 BG composition) were developed by the replica technique using natural marine sponges as sacrificial templates. The resulting scaffolds were characterized by superior mechanical properties (compression strength up to 4 MPa) compared to conventional BG scaffolds prepared using polyurethane (PU) packaging foam as a template. This result was ascribed to a reduction of the total scaffold porosity without affecting the pore interconnectivity (>99%). It was demonstrated that the reduction of total porosity did not affect the bioactivity of the BG-based scaffolds, tested by immersion of scaffolds in simulated body fluid (SBF). After 1 day of immersion in SBF, a homogeneous CaP deposit on the surface of the scaffolds was formed, which evolved over time into carbonate hydroxyapatite (HCA). Moreover, the enhanced mechanical properties of these scaffolds were constant over time in SBF; after an initial reduction of the maximum compressive strength upon 7 days of immersion in SBF (to 1.2 ± 0.2 MPa), the strength values remained almost constant and higher than those of BG-based scaffolds prepared using PU foam (<0.05 MPa). Preliminary cell culture tests with Saos-2 osteoblast cell line, namely direct and indirect tests, demonstrated that no toxic residues remained from the natural marine sponge templates and that cells were able to proliferate on the scaffold surface