Grit Festag

Human adenoma cells are highly susceptible to the genotoxic action of 4-hydroxy-2-nonenal

Oxidative stress and resulting lipid peroxidation are important risk factors for dietary-associated colon cancer. To get a better understanding of the underlying molecular mechanisms, we need to characterise the risk potential of the key compounds, which cause DNA damage in cancer-relevant genes and especially in human target cells. Here, we investigated the genotoxic effects of 4-hydroxy-2-nonenal (HNE) and hydrogen peroxide (H(2)O(2)) in human colon cells (LT97). LT97 is a recently established cell line from a differentiated microadenoma and represents cells from frequent preneoplastic lesions of the colon. The genomic characterisation of LT97 was performed with 24-colour FISH. Genotoxicity was determined with single cell microgelelectrophoresis (Comet assay). Comet FISH was used to study the sensitivity of TP53-a crucial target gene for the transition of adenoma to carcinoma-towards HNE. Expression of glutathione S-transferases (GST), which deactivates HNE, was determined as GST activity and GSTP1 protein levels. LT97 cells were compared to primary human colon cells and to a differentiated clone of HT29. Karyotyping revealed that the LT97 cell line had a stable karyotype with only two clones, each containing a translocation t(7;17) and one aberrant chromosome 1. The Comet assay experiments showed that both HNE and H(2)O(2) were clearly genotoxic in the different human colon cells. HNE was more genotoxic in LT97 than in HT29clone19A and primary human colon cells. After HNE incubation, TP53 migrated more efficiently into the comet tail than the global DNA, which suggests a higher susceptibility of the TP53 gene to HNE. GST expression was significantly lower in LT97 than in HT29clone19A cells, which could explain the higher genotoxicity of HNE in the colon adenoma cells. In conclusion, the LT97 is a relevant model for studying genotoxicity of colon cancer risk factors since colon adenoma are common preneoplastic lesions occurring in advanced age.

π‐Conjugated Donor and Donor–Acceptor Metallo‐Polymers

Two zinc(II)- and two ruthenium(II) containing π-conjugated metallo-polymers were synthesized and characterized in detail. We could prove by SEC, analytical ultracentrifugation (AUC) and viscosimetry the ruthenium(II) metallo-polymers to be high molar mass materials (M(fs)  = 20 000 g · mol(-1) Ru1-2; M(fs)  = 34 000 g · mol(-1) Ru1) exhibiting intrinsic viscosities of up to [η] = 192 · cm(3)  · g(-1) . Applying spin-coating we produced homogeneous films of the polymers and could, subsequently, investigate the photophysical properties in the solid state. Introducing the Ru(II) metallo-polymers mixed with PCBM[60] as photoactive layer in bulk-heterojunction solar cells resulted in very low efficiencies due to morphology problems.

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

In this study liquid chromatography at critical conditions for poly(2-ethyl-2-oxazoline)s (PEtOx) has been performed for the first time in order to analyze functional PEtOx homopolymers and block copolymers. Besides the verification of the critical point of adsorption with two series of ester end group functionalized PEtOx homopolymers, to evaluate the effect of both the chain length dependence and the end group polarity, using a cyano column with a solvent combination of 2-propanol and water, also two-dimensional liquid chromatography (2D-LC) has been applied for a poly(2-oxazoline) block copolymer. The combined characterization techniques provided further information about the polymerization procedure with regard to the formation of side-products by separation of the block copolymer from the corresponding homopolymer impurities. In addition, hyphenation of LCCC with MALDI-TOF MS and ESI-Q-TOF tandem mass spectrometry verified the obtained results.

Amphiphilic supramolecular A(B)2A quasi-triblock copolymers

The efficient synthesis of a responsive amphiphilic supramolecular triblock copolymer A(B)2A is described, where the blocks are held together by self-complementary hydrogen bonding at the homojunction (B–B) and by heteroleptic metal complexes at the heterojunction (A–B). The supramolecular copolymer was prepared in a minimum of steps by using heterotelechelic building blocks with orthogonal binding sites polymerized in one step.

Hydrodynamic Analysis Resolves the Pharmaceutically-Relevant Absolute Molar Mass and Solution Properties of Synthetic Poly(ethylene glycol)s Created by Varying Initiation Sites

The solution behavior originating from molecular characteristics of synthetic macromolecules plays a pivotal role in many areas, in particular the life sciences. This situation necessitates the use of complementary hydrodynamic analytical methods as the only means for a complete structural understanding of any macromolecule in solution. To this end, we present a combined hydrodynamic approach for studying in-house prepared, low dispersity poly(ethylene glycols)s (PEGs), also known as poly(ethylene oxide)s (PEOs) depending on the classification used, synthesized from varying initiation sites by the living anionic ring opening polymerization. The series of linear PEGs in the molar mass range of only a few thousand to 50 000 g mol-1 have been studied in detail via viscometry and sedimentation-diffusion analysis by analytical ultracentrifugation. The obtained estimations for intrinsic viscosity, diffusion coefficients, and sedimentation coefficients of the macromolecules in the solution-based analysis clearly showed self-consistency of the followed hydrodynamic approach. This self-consistency is underpinned by appropriate and physically sound values of hydrodynamic invariants, indicating adequate values of derived absolute molar masses. The classical scaling relations of Kuhn-Mark-Houwink-Sakurada of all molar-mass dependent hydrodynamic estimates show linear trends, allowing for interrelation of all parametric macromolecular characteristics. Differences among these are ascribed to the observation of α-end and chain-length dependent solvation of the macromolecules, identified from viscometric studies. This important information allows for analytical tracing of variations of scaling relationships and a physically sound estimation of hydrodynamic characteristics. The demonstrated self-sufficient methodology paves an important way for a complete structural understanding and potential replacement of pharmaceutically relevant PEGs by alternative macromolecules offering a suite of similar or tractably distinct physicochemical properties.

Amphiphilic and double hydrophilic block copolymers containing a polydehydroalanine block

We present the synthesis and characterization of amphiphilic and double hydrophilic block copolymers containing a polydehydroalanine (PDha) block. First, polystyrene-block-poly(tert-butoxycarbonylaminomethyl acrylate) (PS-b-PtBAMA) and poly(n-butylacrylate)-block-poly(tert-butoxycarbonylaminomethyl acrylate) (PnBA-b-PtBAMA) were prepared by atom transfer radical polymerization (ATRP). Subsequent deprotection led to the corresponding PS-b-PDha and PnBA-b-PDha block copolymers. All intermediate stages were characterized by 1H-, 13C- or solid state MAS 13C-NMR. Afterwards, the solution behavior of PAA-b-PDha was investigated by a combination of dynamic light scattering, zeta potential measurements, and potentiometric titration – revealing that aggregation occurs upon reaching pH values of 3 or lower. In case of PS-b-PDha, core-corona micelles are formed in aqueous solution, as revealed by a combination of DLS and cryogenic transmission electron microscopy.

Chip-based molecular diagnostics using metal nanoparticles

BACKGROUND Chip-based bioanalytical methods represent a promising approach for a highly parallel and robust analysis with minimal sample volumes. Key process parameters that can be decisive for certain applications are determined by the detection scheme utilized. OBJECTIVE This review addresses typical requirements of chip-based detection systems, especially for the emerging field of point-of-care diagnostics that make possible field detection with less-trained personnel, robust assays as well as low instrumentation costs. METHODS The use of metal nanoparticles as labels represents a promising approach. They exhibit a high stability in signal and new detection schemes that would allow for robustness and low-cost readout. RESULTS/CONCLUSION First examples of this kind have been established and are in the market, and more are in the development pipeline.

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 1H 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.

Correction: Amphiphilic and double hydrophilic block copolymers containing a polydehydroalanine block

Correction for ‘Amphiphilic and double hydrophilic block copolymers containing a polydehydroalanine block’ by Mark Billing et al., Polym. Chem., 2017, DOI: 10.1039/c6py02076c.

DNA-conjugated metal nanoparticle for bioanalytics, nanophotonics, and nanoelectronics

Metal (especially gold) nanoparticles exhibit unique electronic, optical, and catalytic properties. In order to utilize these properties, an integration of the particles into technical setups such as a chip surface is helpful. We develop techniques to use (bio) molecular tools in order to address and control the positioning of particles on microstructured chips. These techniques are utilized for novel DNA detection schemes using optical or electrical principles. Plasmonic properties of the particles and the combination of nano-apertures with particles are promising fields for further bioanalytical developments. On the other hand, methods for defined positioning of single molecules or molecular constructs in parallel approaches are under development, in order to provide needed defined nanostructures for applications in nanoelectronics. Connecting DNA with nanoparticles, metallization of DNA or positioning of individual DNA-structures over microstructured electrode gap including subsequent metal particle binding are important steps in this direction. The utilization of (bio) molecular tools and principles based on highly specific binding and self-assembly represent a promising development in order to realize novel nanoparticle-based devices for bioanalytics, nano-optics and - electronics.