Tethering Cells via Enzymatic Oxidative Crosslinking Enables Mechanotransduction in Non-Cell-Adhesive Materials

Cell–matrix interactions govern cell behavior and tissue function by facilitating transduction of biomechanical cues. Engineered tissues often incorporate these interactions by employing cell-adhesive materials. However, using constitutively active cell-adhesive materials impedes control over cell fate and elicits inflammatory responses upon implantation. Here, an alternative cell–material interaction strategy that provides mechanotransducive properties via discrete inducible on-cell crosslinking (DOCKING) of materials, including those that are inherently non-cell-adhesive, is introduced. Specifically, tyramine-functionalized materials are tethered to tyrosines that are naturally present in extracellular protein domains via enzyme-mediated oxidative crosslinking. Temporal control over the stiffness of on-cell tethered 3D microniches reveals that DOCKING uniquely enables lineage programming of stem cells by targeting adhesome-related mechanotransduction pathways acting independently of cell volume changes and spreading. In short, DOCKING represents a bioinspired and cytocompatible cell-tethering strategy that offers new routes to study and engineer cell–material interactions, thereby advancing applications ranging from drug delivery, to cell-based therapy, and cultured meat

Centering Single Cells in Microgels via Delayed Crosslinking Supports Long-Term 3D Culture by Preventing Cell Escape

Single-cell-laden microgels support physiological 3D culture conditions while enabling straightforward handling and high-resolution readouts of individual cells. However, their widespread adoption for long-term cultures is limited by cell escape. In this work, it is demonstrated that cell escape is predisposed to off-center encapsulated cells. High-speed microscopy reveals that cells are positioned at the microgel precursor droplets' oil/water interface within milliseconds after droplet formation. In conventional microencapsulation strategies, the droplets are typically gelled immediately after emulsification, which traps cells in this off-center position. By delaying crosslinking, driving cells toward the centers of microgels is succeeded. The centering of cells in enzymatically crosslinked microgels prevents their escape during at least 28 d. It thereby uniquely enables the long-term culture of individual cells within 90%), maintained metabolic activity (>70%), and multilineage differentiation capacity (>60%) over a period of 28 d. The facile nature of this microfluidic cell-centering method enables its straightforward integration into many microencapsulation strategies and significantly enhances control, reproducibility, and reliability of 3D single cell cultures

On-the-fly exchangeable microfluidic nozzles for facile production of various monodisperse micromaterials

Microfluidic manufacturing platforms have advanced the production of monodisperse, shape-controlled, and chemically defined micromaterials. However, conventional microfabrication platforms are typically designed and fabricated as single-purpose and single-use tools, which limits their efficiency, versatility, and overall potential. We here present an on-the-fly exchangeable nozzle concept that operates in a transparent, 3D, and reusable microfluidic device produced without cleanroom technology. The facile exchange and repositioning of the nozzles readily enables the production of monodisperse water-in-oil and oil-in-water emulsions, solid and core-shell microspheres, microfibers, and even Janus type micromaterials with controlled diameters ranging from 10 to 1000 μm using a single microfluidic device

Applications and level-2 products with the dual-baseline and linear-dual polarimetric MIRANDA35 airborne SAR system

FMCW airborne SAR can collect data from different viewing angles, and can offer rapidly informative imagery of strategic infrastructure, or disaster areas at local scales. As they transmit low power, they can be mounted on light platforms. In 2022 we conducted a measurement campaign with the FHR’s MIRANDA35 system. It allows 1) topographic mapping by means of a tomographic configuration, 2) along-track interferometry for air and ground moving target indication, and 3) polarimetry for target classification and recognition. We show the performance of the system, and diverse level-1 and level-2 products, such as multi-aspect digital elevation models

Microplastic Index—How to Predict Microplastics Formation?

The presence of microplastics in environmental compartments is generally recognized as a (potential) health risk. Many papers have been published on the abundance of microplastics at various locations around the globe, but only limited knowledge is available on possible mitigation routes. One of the mitigation routes is based on the choice of plastic materials used for products that may unintentionally end up in the environment. As a first approach, this paper presents a method to calculate the tendency of polymers to form microplastics, based on their mechanical and physical properties. A MicroPlastic Index (MPI) that correlates the microplastic formation to polymer properties is defined for both impact and wear of polymers via a theoretical particle size and the energy required to form these particles. A first comparison between calculated and experimental particle size is included. The MPI for impact and wear follow the same trend. Finally, these MPIs are correlated to the respective abundance of the microplastics in the environment, corrected for global production of the corresponding polymers: the higher the MPI, the more microplastics are found in the environment. Thus, the MPI can be used as a basis for choice or redesign of polymers to reduce microplastic formation

First results of a joint measurement campaign with PAMIR-Ka and MIRANDA-94

Fraunhofer FHR has participated in the international measurement campaign of the NATO research task group SET-250 with two airborne SAR systems in July 2019. The general objective of the trials was to investigate the use of multidimensional radar to increase the performance of radar imaging systems. The first system PAMIR-Ka is a multi-channel pulsed radar system operating at 34 GHz with a very high bandwidth of up to 8 GHz. The second system MIRANDA-94 is a multichannel frequency modulated continuous wave (FMCW) radar with up to 3 GHz at 94 GHz center frequency with a dual polarized antenna. The paper introduces the systems, explains the data collection, and presents first results with respect to multi-look, multi-frequency, multi-polarization, and multi-aspect radar imaging of a test site with military targets

Droplet microfluidics to engineer smart building blocks for modular tissue engineering

Modular tissue engineering enables the formation of larger 3D multiscale tissues by assembly of building blocks composed of cells and/or (micro)materials. However, current tissue building blocks are static, thereby limiting the functionality of modular tissues. In this study, an advanced droplet microfluidics system is used to produce microgels that are optimized to act as smart tissue building blocks. The cell-sized microgels are functionalized with reactive moieties that allow for the microgels' in situ chemical and mechanical tuning, thereby providing spatiotemporal control over living modular tissues