Search results for "Linker"
showing 10 items of 100 documents
Efficient Shielding of Polyplexes Using Heterotelechelic Polysarcosines
2018
Shielding agents are commonly used to shield polyelectrolyte complexes, e.g. polyplexes, from agglomeration, precipitation in complex media, like blood, and thus enhance their circulation times in vivo. Since up to now primarily poly(ethylene glycol) (PEG) has been investigated to shield non-viral carriers for systemic delivery, we report on the use of polysarcosine (pSar) as a potential alternative for steric stabilization. A redox-sensitive, cationizable lipo-oligomer structure (containing two cholanic acids attached via a bioreducible disulfide linker to an oligoaminoamide backbone in T-shape configuration) was equipped with azide-functionality by solid phase supported synthesis. After m…
Encapsulation of polyprodrugs enables an efficient and controlled release of dexamethasone
2021
Water-soluble low molecular weight drugs, such as the synthetic glucocorticoid dexamethasone (DXM), can easily leak out of nanocarriers after encapsulation due to their hydrophilic nature and small size. This can lead to a reduced therapeutic efficacy and therefore to unwanted adverse effects on healthy tissue. Targeting DXM to inflammatory cells of the liver like Kupffer cells or macrophages is a promising approach to minimize typical side effects. Therefore, a controlled transport to the cells of interest and selective on-site release is crucial. Aim of this study was the development of a DXM-phosphate-based polyprodrug and the encapsulation in silica nanocontainers (SiO2 NCs) for the red…
Novel bile acid conjugates with aryl/alkenyl linker: Synthesis and characterization
2008
Abstract Eight potential precursors for the design of bile acid derived receptors viz. 2,6-bis[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl)ammonio-methyl]naphthalene dibromide (1), 3,3′-bis[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]biphenyl dibromide (2), 3,3′-bis[dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]biphenyl dibromide (3), 4,4′-bis[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]stilbene dibromide (4), 4,4′-bis[dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammoniomethyl]stilbene dibromide (5), allyl-dimethyl(3α,7α,12α-trihydroxy-5β-cholan-24-amidoethyl)ammonium bromide (6), 1,4′-bis[dimethyl(3α-hydroxy-5β-cholan-24-amidoethyl…
New artesunic acid homodimers: Potent reversal agents of multidrug resistance in leukemia cells
2012
Abstract To evade the problem of multidrug resistance, hybridization of natural products in dimers is considered as an effective method. After the successful synthesis of three artesunic acid homodimers connected by different types of chemical linkers, we analyzed their activity against human CCRF-CEM and multidrug-resistant p -glycoprotein-overexpressing CEM/ADR 5000 leukemia cells and observed, that multidrug resistant cells were not cross-resistant to the new compounds. Collateral sensitivity was observed for artesunic acid homodimer 2. The obtained results deliver valuable information about the linker’s structure which is required for homodimers to be highly cytotoxic.
Characterization by solid-state NMR and selective dissolution techniques of anhydrous and hydrated CEM V cement pastes.
2010
International audience; The long term behaviour of cement based materials is strongly dependent on the paste microstructure and also on the internal chemistry. A CEM V blended cement containing pulverised fly ash (PFA) and blastfurnace slag (BFS) has been studied in order to understand hydration processes which influence the paste microstructure. Solid-state NMR spectroscopy with complementary X-ray diffraction analysis and selective dissolution techniques have been used for the characterization of the various phases (C3S, C2S, C3A and C4AF) of the clinker and additives and then for estimation of the degree of hydration of these same phases. Their quantification after simulation of experime…
Some factors affecting an increase in magnetic susceptibility of cement dusts
2001
The aim of the research was to explain reasons of fluctuation in magnetic susceptibility of cement dusts and the consequences for the environment. The research comprised measurements of magnetic susceptibility and Fe content in dusts, and also in raw materials, additives, fuels, mixtures and clinkers used for cement production. The samples were taken in four cement plants located in Opole Province (southern Poland). In addition to this, the influence of two production methods (dry and wet) on magnetic susceptibility of dusts and some aspects of ferrimagnetic minerals formation in the process of clinker burning were considered. It was proven that magnetic susceptibility of dusts depends on r…
Natural fluorapatite as a raw material for Portland clinker
2018
Abstract The present work focuses on the mineralogy and the reactivity of clinkers made from the integration of natural fluorapatite in the raw meals with percentages ranging from 0 up to15%. The samples were characterized by infrared spectrometry, X-ray diffraction and microscopy techniques. The distribution of phosphorous and fluorine into clinkers minerals was determined by MEB/EDS mapping. The mineralogical composition was determined by XRD/Rietveld and the samples reactivity followed by isothermal microcalorimetry. It has been found that fluorine stabilizes C3S and β-C2S which still are found with high levels of P2O5. Cements obtained from up to 8% natural fluorapatite incorporation st…
Organic synthesis of high added value molecules with MOF catalysts
2020
Recent examples of organic synthesis of fine chemicals and pharmaceuticals in confined spaces of MOFs are highlighted and compared with silica-based ordered porous solids, such as zeolites or mesoporous (organo)silica. These heterogeneous catalysts offer the possibility of stabilizing the desired transition states and/or intermediates during organic transformations of functional groups and (C-C/C-N) bond forming steps towards the desired functional high added value molecular scaffolds. A short introduction on zeolites, mesoporous silica and metal-organic frameworks is followed by relevant applications in which confined active sites in the pores promote single or multi-step organic synthesis…
Three-dimensional orientational colocalization of individual donor--acceptor pairs.
2004
We report on the determination of the three-dimensional orientation of the donor and acceptor transition dipoles in individual fluorescence resonance energy transfer (FRET) pairs by means of scanning optical microscopy with annular illumination. Knowledge of the mutual orientation of the donor and acceptor dipole is mandatory for reliable distance determination based on FRET efficiency measurements. In our model system perylenediimide as the donor and terryelenediimide as the acceptor are coupled via a stiff p-terphenyl linker. The absorption dipoles of the donor and acceptor are selectively addressed by the 488 nm and 647 line of an Ar/Kr mixed gas laser, respectively. A clear deviation fr…
Strong Cooperativity and Loose Geometry between CUB Domains Are the Basis for Procollagen C-Proteinase Enhancer Activity
2009
Procollagen C-proteinase enhancers (PCPE-1 and -2) specifically activate bone morphogenetic protein-1 (BMP-1) and other members of the tolloid proteinase family during C-terminal processing of fibrillar collagen precursors. PCPEs consist of two CUB domains (CUB1 and CUB2) and one NTR domain separated by one short and one long linker. It was previously shown that PCPEs can strongly interact with procollagen molecules, but the exact mechanism by which they enhance BMP-1 activity remains largely unknown. Here, we used a series of deletion mutants of PCPE-1 and two chimeric constructs with repetitions of the same CUB domain to study the role of each domain and linker. Out of all the forms teste…