Interpenetrated Magnesium–Tricalcium Phosphate Composite: Manufacture, Characterization and In Vitro Degradation Test

Magnesium and calcium phosphates composites are promising biomaterials to create biodegradable load-bearing implants for bone regeneration. The present investigation is focused on the design of an interpenetrated magnesium–tricalcium phosphate (Mg–TCP) composite and its evaluation under immersion test. In the study, TCP porous preforms were fabricated by robocasting to have a prefect control of porosity and pore size and later infiltrated with pure commercial Mg through current-assisted metal infiltration (CAMI) technique. The microstructure, composition, distribution of phases and degradation of the composite under physiological simulated conditions were analysed by scanning electron microscopy, elemental chemical analysis and X-ray diffraction. The results revealed that robocast TCP preforms were full infiltrated by magnesium through CAMI, even small pores below 2 lm have been filled with Mg, giving to the composite a good interpenetration. The degradation rate of the Mg–TCP composite displays lower value compared to the one of pure Mg during the first 24 h of immersion test.Magnesium and calcium phosphates composites are promising biomaterials to create biodegradable load-bearing implants for bone regeneration. The present investigation is focused on the design of an interpenetrated magnesium–tricalcium phosphate (Mg–TCP) composite and its evaluation under immersion test. In the study, TCP porous preforms were fabricated by robocasting to have a prefect control of porosity and pore size and later infiltrated with pure commercial Mg through current-assisted metal infiltration (CAMI) technique. The microstructure, composition, distribution of phases and degradation of the composite under physiological simulated conditions were analysed by scanning electron microscopy, elemental chemical analysis and X-ray diffraction. The results revealed that robocast TCP preforms were full infiltrated by magnesium through CAMI, even small pores below 2 lm have been filled with Mg, giving to the composite a good interpenetration. The degradation rate of the Mg–TCP composite displays lower value compared to the one of pure Mg during the first 24 h of immersion test

Functionalized Bioink with Optical Sensor Nanoparticles for O<inf>2</inf> Imaging in 3D-Bioprinted Constructs

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Research on 3D bioprinting of living cells has strong focus on printable biocompatible materials and monitoring of cell growth in printed constructs, while cell metabolism is mostly measured in media surrounding the constructs or by destructive sample analyses. Bioprinting is combined with online imaging of O2 by functionalizing a hydrogel bioink via addition of luminescent optical sensor nanoparticles. Rheological properties of the bioink enable 3D printing of hydrogel layers with uniform response to O2 concentration. Co-immobilization of sensor nanoparticles with green microalgae and/or mesenchymal stem cells does not affect cell viability over several days. Interference from microalgal autofluorescence on the O2 imaging is negligible, and no leakage or photobleaching of nanoparticles is observed over 2–3 days. Oxygen dynamics due to respiration and photosynthesis of cells can be imaged online and the metabolic activity of different cell types can be discriminated in intact 3D structures. Bioinks containing chemical sensor particles enable noninvasive mapping of cell metabolism and spatiotemporal dynamics of their chemical microenvironment in 3D-printed structures. This major advance now facilitates rapid evaluation of cell activity in printed constructs as a function of structural complexity, metabolic interactions in mixed species bioprints, and in response to external incubation conditions