Christine Rosenauer

Poly[2]catenanes and Cyclic Oligo[2]catenanes Containing Alternating Topological and Covalent Bonds: Synthesis and Characterization

Large bifunctionalized catenate and catenand, composed of macrocycles containing 45 atoms, have been synthesized and copolymerized with a terephthalic acid derivative to afford a cyclic oligo[2]catenand and a linear poly[2]catenate. Poly[2]catenand was obtained by demetalation of poly[2]-catenate. The molecular weight distribution of these polymers, which are composed of alternating topological and covalent bonds, has been characterized by gel permeation chromatography (GPC) with universal calibration, viscometry, and MALDI-TOF mass spectrometry. We were able to synthesize a poly[2]catenate and a poly[2]catenand with a degree of polymerization (DP) equal to 8-9. In addition, an upper value of the Kuhn segment length of poly[2]catenand has been determined and is discussed in the light of its structure.

Holographic grating study of mass and thermal diffusion of polystyrene/toluene solutions

The transient grating technique of thermal diffusion forced Rayleigh scattering (TDFRS) has been employed to study translational and thermal diffusion of polystyrene in toluene. Different molar masses and concentrations below or slightly above (lie overlap concentrationc* have been investigated. The translational diffusion coefficients agree well with results obtained from photon correlation spectroscopy. Small remaining diferences can be attributed to sample polydispersity. The molar mass independence of the thermal diffusion coefficient is confirmed, and thermal diffusion and Soret coefficients are compared with data obtained from thermal field flow fractionation and diffusion cell experiments.

Poly(vinyl phosphonic acid): Hydrodynamic Properties and SEC-Calibration in Aqueous Solution

Poly(vinyl phosphonic acid) (PVPA) as obtained by free radical polymerization of aqueous vinyl phosphonic acid was studied by light scattering (SLS, DLS) and size exclusion chromatography (SEC) in dilute aqueous solutions containing sufficient salt in order to screen long range electrostatic interactions. Samples of 37<

The Transferability from Animal Models to Humans: Challenges Regarding Aggregation and Protein Corona Formation of Nanoparticles

\overline M _{\rm w}

Determination of molar masses of macromolecules by size exclusion chromatography-light scattering not requiring knowledge of refractive index increments

< 110 × 10(3) were studied. The polymers showed positive A(2) -values in aqueous NaH(2) PO(4) solution (0.04 M), and self-diffusion behavior and R(H) /R(G) -ratios indicative of the structure of random coiled chains. A comparison of the SEC-elugrams of the PVPA-samples with those of commercially available standards of poly(acrylic acid) sodium salt gave a fit to the same calibration curve described by log P(n(PVPA))  = -0.21ν(e)  + 7.0(+0.1) which correlates the number average degree of polymerization (P(n) ) with the elution volume ν(e) . This indicates that PVPA and PAA have the same hydrodynamic structure under given solution conditions.

Synthesis of a Cyclic Monomer of Perdeuterated Poly(ethylmethylsiloxane)

Nanomaterials are interesting candidates for applications in medicine as drug delivery or diagnostic agents. For safe application, they have to be evaluated in in vitro and in vivo models to finally be translated to human clinical trials. However, often those transfer processes fail, and it is not completely understood whether in vitro models leading to these animal models can reliably be compared to the situation in humans. In particular, the interaction of nanomaterials with components from different blood plasma sources is difficult to compare, and the outcomes of those interactions with respect to body distribution and cell uptake are unclear. Therefore, we investigated the interactions of differently functionalized polymeric and inorganic nanoparticles with human, mouse, rabbit, and sheep plasma. The focus was put on the determination of aggregation events of the nanoparticles occurring in concentrated plasma and the correlation with the respectively formed protein coronas. Both the stability in plasma as well as the types of adsorbed proteins were found to strongly depend on the plasma source. Thus, we suggest evaluating the potential use of nanocarriers always in the plasma source of the chosen animal model for in vitro studies as well as in human plasma to pin down differences and eventually enable transfer into clinical trials in humans.

Understanding the elusive protein corona of thermoresponsive nanogels

A new approach for the calibration of SEC-light scattering (SEC-LS) setups is proposed, which requires solely the molar mass of a reference polymer. Neither the specific refractive index increment of the calibrant nor of the analyte is required. Comparison of the molar masses derived in different solvents for a large number of chemically different polymers shows that the new approach yields the same molar masses as if molar masses were derived using dn/dc to calibrate the light scattering setup. The approach therefore allows easier determination of molar masses by SEC-LS.

Zirconium oxocluster/polymer hybrid nanoparticles prepared by photoactivated miniemulsion copolymerization

A new efficient route for the synthesis of a cyclic monomer of perdeuterated poly(ethyl-methylsiloxane) (PEMS) is reported. The perdeuterated cyclotrisiloxane has been prepared for the first time in an eight-step reaction starting from fully deuterated methanol and ethanol. Chromatographic and spectroscopical methods indicate a high purity as well as almost total deuteration of the 2,4,6-tri(pentadeuteroethyl)-2,4,6-tri(trideuteromethyl)cyclotrisiloxane. All the reaction steps have been previously investigated by the similar preparation of the protonated 2,4,6-triethyl-2,4,6-trimethylcyclotrisiloxane as a model for the synthesis of the corresponding perdeuterated monomer.

Determination of the Micelle Architecture of Polystyrene Poly(4-Vinylpyridine) Block-Copolymers in Dilute-Solution

AIM We analyzed the protein corona of thermoresponsive, poly(N-isopropylacrylamide)- or poly(N-isopropylmethacrylamide)-based nanogels. MATERIALS & METHODS Traces of protein corona detected after incubation in human serum were characterized by proteomics and dynamic light scattering in undiluted serum. RESULTS Apolipoprotein B-100 and albumin were the main components of the protein coronae. For dendritic polyglycerol-poly(N-isopropylacrylamide) nanogels at 37°C, an increase in adsorbed immunoglobulin light chains was detected, followed by partially reversible nanogel aggregation. All nanogels in their hydrophilic state are colloidally stable in serum and bear a dysopsonin-rich protein corona. CONCLUSION We observed strong changes in NG stability upon slight alterations in the composition of the protein coronae according to nanogel solvation state. Nanogels in their hydrophilic state possess safe protein coronae.

Synthesis and size control of polystyrene latices via polymerization in microemulsion

The photoactivated free radical miniemulsion copolymerization of methyl methacrylate (MMA) and the zirconium oxocluster Zr4O2(methacrylate)12 is used as an effective and fast preparation method for polymer/inorganic hybrid nanoparticles. The oxoclusters, covalently anchored to the polymer network, act as metal-organic cross-linkers, thus improving the thermomechanical properties of the resulting hybrid nanoparticles. Benzoin carbonyl organic compounds were used as photoinitiators. The obtained materials are compared in terms of cross-linking, effectiveness of cluster incorporation, and size distribution with the analogous nanoparticles produced by using conventional thermally induced free radical miniemulsion copolymerization. The kinetics of the polymerization process in the absence and in the presence of the oxocluster is also investigated.