Some aspects of the surface chemistry of carbon blacks and other carbons

/pdf/the-surface-chemistry-of-amorphous-silica-zhuravlev-model-4kfs2lx66q.pdf

The surface chemistry of amorphous silica. Zhuravlev model

Tissues can be soft like fat, which bears little stress, or stiff like bone, which sustains high stress, but whether there is a systematic relationship between tissue mechanics and differentiation is unknown. Here, proteomics analyses revealed that levels of the nucleoskeletal protein lamin-A scaled with tissue elasticity, E, as did levels of collagens in the extracellular matrix that determine E. Stem cell differentiation into fat on soft matrix was enhanced by low lamin-A levels, whereas differentiation into bone on stiff matrix was enhanced by high lamin-A levels. Matrix stiffness directly influenced lamin-A protein levels, and, although lamin-A transcription was regulated by the vitamin A/retinoic acid (RA) pathway with broad roles in development, nuclear entry of RA receptors was modulated by lamin-A protein. Tissue stiffness and stress thus increase lamin-A levels, which stabilize the nucleus while also contributing to lineage determination.

/pdf/nuclear-lamin-a-scales-with-tissue-stiffness-and-enhances-m0l552r7vs.pdf

Nuclear lamin-A Scales With Tissue Stiffness and Enhances Matrix-Directed Differentiation

Soft connective tissues at steady state are dynamic; resident cells continually read environmental cues and respond to them to promote homeostasis, including maintenance of the mechanical properties of the extracellular matrix (ECM) that are fundamental to cellular and tissue health. The mechanosensing process involves assessment of the mechanics of the ECM by the cells through integrins and the actomyosin cytoskeleton, and is followed by a mechanoregulation process, which includes the deposition, rearrangement or removal of the ECM to maintain overall form and function. Progress towards understanding the molecular, cellular and tissue-level effects that promote mechanical homeostasis has helped to identify key questions for future research.

Mechanotransduction and extracellular matrix homeostasis

http://www.css.cornell.edu/faculty/lehmann/publ/OrgGeochem%2037,%201477-1488,%202006%20Cheng%20www.pdf

Oxidation of Black Carbon by Biotic and Abiotic Processes

Reaction of Organolithium Compounds with Silicon Dioxide

Um die mit der Zelladhasion zusammenhangenden molekularen Signalwege aufzuklaren, bieten synthetische Zellen den einzigartigen Vorteil eines gut kontrollierten Modellsystems mit reduzierter molekularer Komplexitat. In der vorliegenden Arbeit zeigen wir, dass Liposome mit rekonstituiertem Blutplattchenintegrin αIIbβ3 als adhasionsvermittelndes Transmembranprotein fur ein funktionales, minimales Zellmodell dienen konnen, um zellulare Adhasionsmechanismen in einer definierten Umgebung zu studieren. Die Wechselwirkung dieser synthetischen Zellen mit unterschiedlichen extrazellularen Matrixproteinen wurde mithilfe der Quarzkristallmikrowaage mit Dissipationsanalyse (QCM-D; quartz crystal microbalance with dissipation monitoring) untersucht. Die Daten zeigten, dass Integrin funktionell in die Lipidvesikel inkorporiert wurde, wodurch die integrinspezifische Adhasion der hergestellten Liposome auf mit Fibrinogen (Fg) und Fibronektin (Fn) funktionalisierten Oberflachen moglich war. Anschliesend konnte das Ablosen der Integrin-Liposome von diesen Oberflachen bei Zugabe des Peptids GRGDSP eingeleitet werden. Effizienter erfolgte das Ablosen mit unserem neu synthetisierten Peptidmimetikum SN529, das spezifisch Integrin αIIbβ3 blockiert.

Synthetische Adhäsion von Integrin-Liposomen als minimales Zellmodell

The extracellular matrix (ECM) represents a highly charged and hydrated network in which different cells in vertebrate tissues are embedded. Hydrogels as minimal ECM mimetics with a controlled chemistry offer the opportunity to vary material properties by varying the negative network charge. In this paper, a synthetic biology model of the ECM based on natural and highly negatively charged polyelectrolyte hyaluronic acid (HA) is characterized with specific emphasis on its charge-related bioactivity. Therefore, the thiol-Michael addition click reaction is used to produce HA hydrogels with defined network structure and charge density. The presented hydrogels show enzymatic degradability and cell attachment. These properties depend on both covalent and electrostatic interactions within the hydrogel network. Furthermore, no unspecific or specific attachment of proteins to the presented hydrogels is observed. In addition, these fundamental insights into charge-related ECM behavior and the influence of electrostatic properties could also lead to innovations in existing biomedical products.

https://www.mdpi.com/1420-3049/23/4/769/pdf

Charge-Controlled Synthetic Hyaluronan-Based Cell Matrices

Controlled activation of lymphangiogenesis through functional biomaterials represents a promising approach to support wound healing after surgical procedures, yet remains a challenge. In a synthetic biological approach, we therefore set out to mimic the basal microenvironment of human primary dermal lymphatic endothelial cells (LECs) during lymphangiogenesis. As the extracellular matrix component hyaluronan (HA) regulates lymphangiogenesis, we designed a bifunctional surface in which adhesive peptide ligands and short HA oligosaccharides (sHA) tethered to nanoparticles are co-presented to the basal side of LECs in a controlled, concentration dependent manner. Exposure of LECs to sHA in solution to mimic luminal stimulation of the cells did not result in modified metabolic activity. However, LECs grown on the bifunctional adhesive surfaces showed a biphasic change in metabolic activity, with increased metabolic activity being observed in response to increasing nanoparticle densities up to a maximum of 540 particles/ µm2. Thus, interfaces that concomitantly present adhesive ligands and sHA can stimulate LEC metabolism and might be able to trigger lymphangiogenesis.

/pdf/effect-of-co-presentation-of-adhesive-ligands-and-short-3xualr5jg8.pdf

Heike Boehm

Papers

Reaction of Organolithium Compounds with Silicon Dioxide

Synthetische Adhäsion von Integrin-Liposomen als minimales Zellmodell

Charge-Controlled Synthetic Hyaluronan-Based Cell Matrices

Effect of Co-presentation of Adhesive Ligands and Short Hyaluronan on Lymphendothelial Cells.