Kinetics of rapid covalent bond formation of aniline with humic acid: ESR investigations with nitroxide spin labels

ABSTRACT The bioavailability of many soil contaminants depends on their interaction with the soil organic matter. The paper presents a new approach of using stable paramagnetic spin labels for investigating the kinetics of covalent binding of specific xenobiotic functional groups with humic acids, a major organic matter fraction. Leonardite humic acid (LHA) was incubated with the nitroxide spin labels amino-TEMPO (4-amino-2,2,6,6-Tetramethylpiperidin-1-oxyl) and anilino-NO (2,5,5-Trimethyl-2-(3-aminophenyl)pyrrolidin-1-oxyl), respectively, which contain an aliphatic or aromatic functionality susceptible to interaction with LHA. Electron spin resonance (ESR) spectra of LHA samples without and with the enzyme laccase were recorded at X-band frequency (9.43 GHz) at room temperature and neutral pH. Binding was detected by a pronounced broadening of the spectral lines after incubation of LHA for both spin labels. The development of a broad signal component in the spectrum of anilino-NO indicated the immobilization due to strong binding of the aniline group. The reorientational correlation time of bound anilino-NO is more than two orders of magnitude greater than that of the free label. The ratio of the amount of bound to the unbound species was used to determine the kinetics of the covalent bond formation. Reaction rate constants of 0.16 min-1 and 0.01 min-1 were determined corresponding to half-times of 4.3 min and 69.3 min, respectively. Treatment of LHA with laccase enhanced the amount of the reacting anilino-NO species by a factor of 7.6, but left the reaction rate unaltered. Oxidative radical coupling was excluded by using the spin trap agent n-tert-butyl-alpha-phenylnitrone

Rapid fabrication and screening of tailored functional 3D biomaterials: Validation in bone tissue repair – Part II

Regenerative medicine strategies place increasingly sophisticated demands on 3D biomaterials to promote tissue formation at sites where tissue would otherwise not form. Ideally, the discovery/fabrication of the 3D scaffolds needs to be high-throughput and uniform to ensure quick and in-depth analysis in order to pinpoint appropriate chemical and mechanical properties of a biomaterial. Herein we present a versatile technique to screen new potential biocompatible acrylate-based 3D scaffolds with the ultimate aim of application in tissue repair. As part of this process, we identified an acrylate-based 3D porous scaffold that promoted cell proliferation followed by accelerated tissue formation, pre-requisites for tissue repair. Scaffolds were fabricated by a facile freeze-casting and an in-situ photo-polymerization route, embracing a high-throughput synthesis, screening and characterization protocol. The current studies demonstrate the dependence of cellular growth and vascularization on the porosity and intrinsic chemical nature of the scaffolds, with tuneable 3D scaffolds generated with large, interconnected pores suitable for cellular growth applied to skeletal reparation. Our studies showed increased cell proliferation, collagen and ALP expression, while chorioallantoic membrane assays indicated biocompatibility and demonstrated the angiogenic nature of the scaffolds. VEGRF2 expression in vivo observed throughout the 3D scaffolds in the absence of growth factor supplementation demonstrates a potential for angiogenesis. This novel platform provides an innovative approach to 3D scanning of synthetic biomaterials for tissue regeneration

Combinatorial Delivery of Bioactive Molecules by a Nanoparticle-Decorated and Functionalized Biodegradable Scaffold

The combination of supportive biomaterials and bioactive factors to stimulate endogenous progenitor cells is of key interest for the treatment of conditions in which intrinsic bone healing capacities are compromised. To address this need a “scaffold-decoration platform” was developed in which a biocompatible, biotin-functionalised 3D structural polymer network was generated through a solvent blending process, and used to recruit avidin modified nanoparticles within its 3D structure through biotin-avidin conjugation. This was enabled via the generation of a suite of poly(lactic-co-glycolic acid) (PLGA) nanoparticles, encapsulating two bioactive factors, vascular endothelial growth factor (VEGF) and L-Ascorbic acid 2-phosphate (AA2P) and conjugated to streptavidin to allow attachment to the bone generating scaffold. The levels of encapsulated and released VEGF and AA2P were tailored to fall within the desired range to promote biological activity as confirmed by an increase in endothelial cell tubule formation and collagen production by osteoblast cells in response to nanoparticle release of VEGF and AA2P, respectively. The release of VEGF from the scaffolds produced a significant effect on vasculature development within the chick chorioallantoic membrane (CAM) angiogenic assay. Similarly, the scaffolds showed strong biological effects in ex vivo assays indicating the potential of this platform for localised delivery of bioactive molecules with applications in both hard and soft tissue engineering

Optimierungsvarianten der Überschussschlammbehandlung einer Sickerwasseranlage

Der vorliegende Bericht ist ein ökonomischer Vergleich verschiedener Varianten der Überschussschlamm (ÜSS)-Verwertung der Sickerwasseranlage auf der Deponie des Entsorgungszentrums Leppe mit dem aktuellen Entsorgungsweg. Als Vergleichsparameter werden die Jahresvollkosten herangezogen. Der derzeitige Entsorgungsweg über die kommunale Kläranlage wird hierbei als Basisvariante betrachtet und mit alternativen Behandlungs- und Verwertungsmöglichkeiten verglichen. Hierbei werden verschiedene Varianten mit unterschiedlichen Ausführungen der Komponenten Lagerung, Entwässerung, Trocknung, Transport und Verbrennung gegenübergestellt

Coherent coupling between exciton resonances governed by the disorder potential

Monolayer fluctuations in the thickness of a semiconductor quantum well (QW) lead to the formation of spectrally resolved excitons located in the narrower, average, and thicker regions of the QW. Whether or not these excitons are coherently coupled via Coulomb interaction is a long-standing debate. We demonstrate that different types of disorder potential govern coherent coupling among excitons, and the coupling strength can be quantitatively measured using optical two-dimensional Fourier transform spectroscopy. Strong coherent coupling occurs between certain types of excitons but is missing between other types of excitons because the distinctive nature of excitons results in different spatial overlap. Our finding may be applicable to other disordered systems, such as photosynthesis and conjugated polymers, where exciton coupling plays a critical role in determining charge and energy transfer

Cell Discovery / Cancer cell specific inhibition of Wnt/-catenin signaling by forced intracellular acidification

Use of the diabetes type II drug Metformin is associated with a moderately lowered risk of cancer incidence in numerous tumor entities. Studying the molecular changes associated with the tumor-suppressive action of Metformin we found that the oncogene SOX4, which is upregulated in solid tumors and associated with poor prognosis, was induced by Wnt/-catenin signaling and blocked by Metformin. Wnt signaling inhibition by Metformin was surprisingly specific for cancer cells. Unraveling the underlying specificity, we identified Metformin and other Mitochondrial Complex I (MCI) inhibitors as inducers of intracellular acidification in cancer cells. We demonstrated that acidification triggers the unfolded protein response to induce the global transcriptional repressor DDIT3, known to block Wnt signaling. Moreover, our results suggest that intracellular acidification universally inhibits Wnt signaling. Based on these findings, we combined MCI inhibitors with H+ ionophores, to escalate cancer cells into intracellular hyper-acidification and ATP depletion. This treatment lowered intracellular pH both in vitro and in a mouse xenograft tumor model, depleted cellular ATP, blocked Wnt signaling, downregulated SOX4, and strongly decreased stemness and viability of cancer cells. Importantly, the inhibition of Wnt signaling occurred downstream of -catenin, encouraging applications in treatment of cancers caused by APC and -catenin mutations.(VLID)270614