Chip-basierter DNA-Nachweis mithilfe metallischer Nanostrukturen

DNA microarrays are promising tools for fast and highly parallel DNA detection. However, the substrate modification (as a prerequisite for capture DNA binding)often leads to inhomogeneous surfaces and/or nonspecific binding of the labeled DNA. Due to their interesting physical properties gold nanoparticles are of growing interest as labels in biomolecular detection. Especially for point-of-care analyses they may overcome some of the drawbacks of fluorescence detection based on their simple optical or electrical readout. Thereby, specific metal deposition on the nanoparticles is of outstanding importance for signal enhancement. However, a broad understanding of the influence of enhancement solution, incubation time, and seed size is still lacking as well as the growth characteristics of conductive metal labels in electrode gaps, especially with regard to electrical detection schemes

Kontrollierbare Zeitverzögerung beim Aufplatzen von oxidationsempfindlichen, mittels PISA synthetisierten Polymersomen

Reaktive Polymersomen sind ein vielseitiges künstliches Nanotransportsystem, das eine Freisetzung als Reaktion auf einen bestimmten Stimulus ermöglichen kann. Die vorgestellten oxidationsempfindlichen Polymersomen zeigen einen zeitlich verzögerten Freisetzungsmechanismus in einer oxidativen Umgebung, der durch Anpassung der Membrandicke oder partielle Voroxidation variierbar ist. Diese polymeren Vesikel werden mittels PISA hergestellt, wodurch eine direkte, effektive In‐situ‐Einkapselung von Molekülen ermöglicht wird, wie z. B. für Farbstoffe und Enzyme gezeigt wurde. Kinetische Studien ergaben, dass ein kritischer Oxidationsgrad die Destabilisierung der Membran bewirkt, während vorab keine Freisetzung der Ladung erfolgt. Die Einkapselung von Glukoseoxidase verwandelt diese Polymersomen direkt in glukoseempfindliche Vesikel, da kleine Moleküle, wie Zucker, ihre Membran passiv durchdringen können. Dank der einfachen Herstellung bieten die Polymersomen eine vielseitige Plattform für den Einschluss und die Freisetzung von Molekülen nach einer genau einstellbaren Zeitspanne in Gegenwart spezifischer Verbindungen wie H 2 O 2 oder Glukose

Characterization of poly(2-oxazoline) homo- and copolymers by liquid chromatography at critical conditions

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Retinol initiated poly(lactide) s: stability upon polymerization and nanoparticle preparation

The synthesis of retinol initiated polylactide (PLA) by ring opening polymerization (ROP) of L-lactide via in situ calcium alkoxide formation with all-trans-retinol and Ca[N(SiMe3)(2)](2)(THF)(2) is described. PLAs with degree of polymerization (DP) values ranging from 13 to 60 were obtained and characterized in detail by means of H-1 nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC), UV/vis spectroscopy and (tandem) mass spectrometry techniques. Stable nanoparticles (NPs) were prepared via a nanoprecipitation method and characterized by DLS and SEM. The stability of retinol upon conjugation to PLA as well as the nanoparticle formulation was investigated in detail and found to be significantly affected by the storage conditions such as exposure to light, oxygen and temperature

Easy Access to Amphiphilic Heterografted Poly(2-oxazoline) Comb Copolymers

A series of heterografted polymers with a polymethacrylate backbone and varying composition of oligomeric 2-oxazoline side chains was synthesized by copolymerization of oligo­(2-ethyl-2-oxazoline)­methacrylate and oligo­(2-<i>n</i>-nonyl-2-oxazoline)­methacrylate (ONonOx) macromonomers using the reversible addition–fragmentation chain transfer (RAFT) technique. Kinetic studies revealed pseudofirst order kinetics, PDI values below 1.3, and a slight enrichment of ONonOx side chains toward the end of the reaction. The heterografted comb polymers were characterized by means of ¹H NMR spectroscopy (0 to 100 mol % ONonOx) and size exclusion chromatography. Differential scanning calorimetry and wide-angle X-ray scattering revealed partial crystallinity of the lateral <i>n</i>-nonyl chains within the ONonOx domains. Depending on the composition of the amphiphilic copolymer, the comb polymers either formed unimers or aggregated (super)­structures in water, methanol, and ethanol, as investigated by dynamic light scattering and cryo-transmission electron microscopy

The gut fermentation product butyrate, a chemopreventive agent, suppresses glutathione S-transferase theta (hGSTT1) and cell growth more in human colon adenoma (LT97) than tumor (HT29) cells.

Contains fulltext : 48397.pdf (publisher's version ) (Closed access)PURPOSE: The gut fermentation product of dietary fiber, butyrate, inhibits growth of HT29, an established tumor cell line. It also induces detoxifying enzymes belonging to the glutathione S-transferase family (GSTs), namely hGSTM2, hGSTP1, hGSTA4, but not of hGSTT1 . Here we investigated kinetics of effects in HT29 and compared sensitivities with preneoplastic LT97 colon adenoma cells, to assess mechanisms of colon cancer chemoprevention in two stages of cell transformation. METHODS: We determined cell growth after butyrate treatment by quantifying DNA, GST expression by Northern/Western Blotting or biochemical analysis and butyrate consumption by measuring the residual concentrations in the cell culture supernatants. Stability of GST-theta (hGSTT1) mRNA was assessed in HT29 cells after inhibition of transcription with actinomycin D. RESULTS: LT97 adenoma cells consumed twofold more butyrate and were more sensitive to growth inhibition than HT29 (EC(50)1.9 mM and 4.0 mM, respectively). Butyrate did not induce GSTs, but instead reduced hGSTT1 in LT97 and HT29. CONCLUSIONS: Butyrate has suppressing-agent activities in human colon cells by inhibiting two survival factors, namely hGSTT1 and cell growth, with LT97 more sensitive than HT29. These findings indicate that butyrate formation in the gut lumen of humans could be protective by reducing survival of transformed colon cells