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.

The wide use of natural fibers has a long-standing history in Africa. In northern Angola, three native fiber plant species, namely Urena lobata, Triumfetta cordifolia, and Dombeya burgessiae, were investigated with regard to their potential usage in modern applications, such as green composites. Bast fibers of the three species were analyzed morphologically, chemically, and mechanically to determine properties such as fiber density, cellulose content, Young's modulus, tensile strength, and breaking strain. In comparison to other natural fibers, all three species were characterized by high Young's moduli up to 60 GPa and tensile strengths up to 950 MPa, yet retting is crucial to unfold the maximum strength of the fibers. Extending the retting time revealed higher values but probably negatively influences economic efficiency. The results demonstrated that the analyzed plants deliver strong and resistant fibers; based on their biomechanical performance, they are alternatives to commercially used natural fibers, such as jute (Corchorus spp.). However, as with other natural fibers, there was high variation in the mechanical properties in the studied species.

Etidronic acid (1-Hydroxyethylidene-1,1-diphosphonic acid, HEDP, H4L) is a proposed decorporation agent for U(VI). This paper studied its complex formation with Eu(III), an inactive analog of trivalent actinides, over a wide pH range, at varying metal-to-ligand ratios (M:L) and total concentrations. Combining spectroscopic, spectrometric, and quantum chemical methods, five distinct Eu(III)−HEDP complexes were found, four of which were characterized. The readily soluble EuH2L+ and Eu(H2L)2− species with log β values of 23.7 ± 0.1 and 45.1 ± 0.9 are formed at acidic pH. At near-neutral pH, EuHL0s forms with a log β of ~23.6 and, additionally, a most probably polynuclear complex. The readily dissolved EuL− species with a log β of ~11.2 is formed at alkaline pH. A six-membered chelate ring is the key motif in all solution structures. The equilibrium between the Eu(III)–HEDP species is influenced by several parameters, i.e., pH, M:L, total Eu(III) and HEDP concentrations, and time. Overall, the present work sheds light on the very complex speciation in the HEDP–Eu(III) system and indicates that, for risk assessment of potential decorporation scenarios, side reactions of HEDP with trivalent actinides and lanthanides should also be taken into account.