Christine Rosenauer - Academia.edu (original) (raw)

Papers by Christine Rosenauer

Polymer Chemistry

Diffusion-ordered NMR spectroscopy (DOSY) allows for excellent determination of block copolymer m... more Diffusion-ordered NMR spectroscopy (DOSY) allows for excellent determination of block copolymer molecular weights.

International Journal of Thermophysics, 1995

... 7, 8]. Compared to other techniques, a properly conducted heterodyne TDFRS experiment has sev... more ... 7, 8]. Compared to other techniques, a properly conducted heterodyne TDFRS experiment has several advantages, such as the high sensitivity of holographic detection, the minute perturbations of the sample, and the convenient subsecond lifetime of the concentration grating. ...

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

Journal of Chromatography A, Oct 1, 2017

 A new approach to calibrate SEC-light scattering setups is proposed.  The approach requires ne... more  A new approach to calibrate SEC-light scattering setups is proposed.  The approach requires neither dn/dc of calibrant nor of analyte  Only molar mass of the reference standard and the injected masses of calibrant and analyte are needed Abstract 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.

Macromolecules, Aug 13, 2021

Designed Monomers & Polymers, 1999

A new efficient route for the synthesis of a cyclic monomer of perdeuterated poly(ethylmethylsilo... more A new efficient route for the synthesis of a cyclic monomer of perdeuterated poly(ethylmethylsiloxane) (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 2,4,6tri(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.

Macromolecular Chemistry and Physics, Aug 1, 2000

The application of a poly(dimethylsiloxane) (PDMS) calibration curve for size exclusion chromatog... more The application of a poly(dimethylsiloxane) (PDMS) calibration curve for size exclusion chromatography (SEC) to poly(ethylmethylsiloxane) (PEMS) leads to molar masses, which are 15–40% higher than expected compared to measurements of the absolute molar mass values. As for the analysis of physical properties of PEMS, the exact knowledge of the molar mass is fundamental, therefore PEMS calibration curves for both SEC and viscometry were established. Eleven narrow distributed linear PEMS samples in the range between 4 000 and 110 000 g/mol were synthesised by anionic ring-opening polymerisation of a cyclic monomer. The molar masses of the PEMS samples were determined by matrix assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS), light scattering, membrane osmometry, vapour pressure osmometry, and by viscometry. The polydispersities calculated from MALDI-TOF-MS spectra were lower compared to the SEC results. With the help of universal calibration, a SEC calibration curve for PEMS was established. Small angle neutron scattering (SANS) experiments on a 50%/50% protonated/deuterated PEMS blend match exactly the molar mass obtained from the PEMS calibration curve for SEC.

Die Makromolekulare Chemie, Rapid Communications

Size-exclusion chromatography (SEC) of polyelectrolytes, particularly of poly-') Systematic IUPAC... more Size-exclusion chromatography (SEC) of polyelectrolytes, particularly of poly-') Systematic IUPAC name: poly[ 1-(N-benzylpyridinio-2-yl)ethylene bromide].

Advanced Materials

Translating innovative nanomaterials to medical products requires efficient manufacturing techniq... more Translating innovative nanomaterials to medical products requires efficient manufacturing techniques that enable large‐scale high‐throughput synthesis with high reproducibility. Drug carriers in medicine embrace a complex subset of tasks calling for multifunctionality. Here, the synthesisof pro‐drug‐loaded core cross‐linked polymeric micelles (CCPMs) in a continuous flow processis reported, which combines the commonly separated steps of micelle formation, core cross‐linking, functionalization, and purification into a single process. Redox‐responsive CCPMs are formed from thiol‐reactive polypept(o)ides of polysarcosine‐block‐poly(S‐ethylsulfonyl‐l‐cysteine) and functional cross‐linkers based on dihydrolipoic acid hydrazide for pH‐dependent release of paclitaxel. The precisely controlled microfluidic process allows the production of spherical micelles (Dh = 35 nm) with low polydispersity values (PDI < 0.1) while avoiding toxic organic solvents and additives with unfavorable safety ...

Macromolecular Rapid Communications

After intravenous administration of nanocarriers, plasma proteins may rapidly adsorb onto their s... more After intravenous administration of nanocarriers, plasma proteins may rapidly adsorb onto their surfaces. This process hampers the prediction of the nanocarriers’ pharmacokinetics as it determines their physiological identity in a complex biological environment. Toward clinical translation it is therefore an essential prerequisite to investigate the nanocarriers’ interaction with plasma proteins. Here, this work evaluates a highly “PEGylated” squaric ester‐based nanogel with inherent prolonged blood circulation properties. After incubation with human blood plasma, the nanogels are isolated by asymmetrical flow‐field flow fractionation. Multiangle light scattering measurements confirm the absence of significant size increases as well as aggregation upon plasma incubation. However, proteomic analyses by gel electrophoresis find minor absolute amounts of proteins (3 wt%), whereas label‐free liquid chromatography mass spectrometry identify 65 enriched proteins. Interestingly, the relati...

ACS Nano, 2021

Therapy resistance is the major cause of cancer death. As patients respond heterogeneously, preci... more Therapy resistance is the major cause of cancer death. As patients respond heterogeneously, precision/personalized medicine needs to be considered, including the application of nanoparticles (NPs). The success of therapeutic NPs requires to first identify clinically relevant resistance mechanisms and to define key players, followed by a rational design of biocompatible NPs capable to target resistance. Consequently, we employed a tiered experimental pipeline from in silico to analytical and in vitro to overcome cisplatin resistance. First, we generated cisplatin-resistant cancer cells and used next-generation sequencing together with CRISPR/Cas9 knockout technology to identify the ion channel LRRC8A as a critical component for cisplatin resistance. LRRC8A's cisplatin-specificity was verified by testing free as well as nanoformulated paclitaxel or doxorubicin. The clinical relevance of LRRC8A was demonstrated by its differential expression in a cohort of 500 head and neck cancer patients, correlating with patient survival under cisplatin therapy. To overcome LRRC8A-mediated cisplatin resistance, we constructed cisplatin-loaded, polysarcosine-based core cross-linked polymeric NPs (NP Cis , Ø ∼ 28 nm) with good colloidal stability, biocompatibility (low immunogenicity, low toxicity, prolonged in vivo circulation, no complement activation, no plasma protein aggregation), and low corona formation properties. 2D/3D-spheroid cell models were employed to demonstrate that, in contrast to standard of care cisplatin, NP Cis significantly (p < 0.001) eradicated all cisplatin-resistant cells by circumventing the LRRC8A-transport pathway via the endocytic delivery route. We here identified LRRC8A as critical for cisplatin resistance and suggest LRRC8A-guided patient stratification for ongoing or prospective clinical studies assessing therapy resistance to nanoscale platinum drug nanoformulations versus current standard of care formulations.

Advanced Science, 2021

Spraying of agrochemicals (pesticides, fertilizers) causes environmental pollution on a million‐t... more Spraying of agrochemicals (pesticides, fertilizers) causes environmental pollution on a million‐ton scale. A sustainable alternative is target‐specific, on‐demand drug delivery by polymeric nanocarriers. Trunk injections of aqueous nanocarrier dispersions can overcome the biological size barriers of roots and leaves and allow distributing the nanocarriers through the plant. To date, the fate of polymeric nanocarriers inside a plant is widely unknown. Here, the in planta conditions in grapevine plants are simulated and the colloidal stability of a systematic series of nanocarriers composed of polystyrene (well‐defined model) and biodegradable lignin and polylactic‐co‐glycolic acid by a combination of different techniques is studied. Despite the adsorption of carbohydrates and other biomolecules onto the nanocarriers’ surface, they remain colloidally stable after incubation in biological fluids (wood sap), suggesting a potential transport via the xylem. The transport is tracked by flu...

Advanced Materials Technologies, 2020

The utilization of solution‐processable organic semiconducting (OSC) polymers and the development... more The utilization of solution‐processable organic semiconducting (OSC) polymers and the development of industrial‐relevant printing techniques enable cost‐efficient fabrication of optoelectronic devices for the mass market. Yet, the adaptation of viscoelastic properties of a functional ink to the respective printing technology is challenging. One crucial parameter is the formulation of the ink, which can be adjusted by selecting the combination of solvents that are mixed with the OSC. The current study considers model functional inks composed of a poly‐phenylene‐vinylene‐based OSC and two solvents, empirically known to be good. Their quality is quantified using the Hansen solubility parameters. The influence of the composition of the solvent mixture on structural, dynamical, and rheological behavior of the ink is investigated with light scattering, viscometry, and rheometry. Although both solvents are considered good, polymer aggregation is found at all compositions. Aggregation depen...

Biointerphases, 2020

The overall success of nanocarriers in biomedical applications depends on their interaction with ... more The overall success of nanocarriers in biomedical applications depends on their interaction with different proteins in blood. Immunoglobulins as a major protein class of the blood proteome may considerably influence the identity of the nanocarriers in blood. However, there is a lack of knowledge about the specific details of the interaction mechanism between different immunoglobulins and nanocarriers. Therefore, the authors have investigated the interaction of different immunoglobulin classes—namely, immunoglobulin G, A, and M—with different polystyrene model nanoparticles. The authors report that immunoglobulin interaction with nanoparticles strongly depends on the immunoglobulin class and surface charge of the nanoparticles. Furthermore, upon adsorption on the nanoparticles’ surfaces, aggregation processes and denaturation of immunoglobulins were observed. This highlights the importance of nanocarriers’ design in order to prevent unfavorable denaturation and adsorption processes o...

ACS Sustainable Chemistry & Engineering, 2019

Yearly the mushroom industry generates several million tons of spent mushroom substrate (SMS), a ... more Yearly the mushroom industry generates several million tons of spent mushroom substrate (SMS), a mixture of composted soil and fungal mycelium, left after the mushroom harvest. Although containing valuable ingredients like carbohydrates, lignin, and diverse enzymes, the substrate is unutilized and causes immense disposal costs. In order to valorize SMS, it is essential to fractionate the complex mixture into its valuable components, which is a challenge for current biorefineries and has only been partly achieved. We have developed a novel biorefinery strategy in order to separate carbohydrates and soluble lignin from SMS. Therefore, SMS was subjected to two different extraction methods in order to break the insoluble biopolymer residues: A, a thermochemical treatment (water/basic or acidic catalyst) yielding a carbohydrate-enriched liquid fraction; B, an organosolv extraction (with ethanol/water) solubilizing mainly lignin. The carbohydrate fraction possesses surface-active properties and was investigated as a potential biobased surfactant. The soluble lignin fraction was used for the formation of nanocarriers via an inverse miniemulsion polymerization. The lignin-based nanocarriers were biodegradable by laccases, which renders them of high interest for drug delivery systems for advanced plant protection. This novel biorefinery is a powerful strategy for the upcycling of SMS into various high-value products.

Nanomedicine, 2018

Aim: We analyzed the protein corona of thermoresponsive, poly(N-isopropylacrylamide)- or poly(N-i... more 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.

Biomacromolecules, Feb 12, 2018

Nanomaterials are interesting candidates for applications in medicine as drug delivery or diagnos... more 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. Bot...

Nanotechnology, 2017

The photoactivated free radical miniemulsion copolymerization of methyl methacrylate (MMA) and th... more 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.

Nanoscale, Jan 14, 2016

The encapsulation of payloads in micro- to nano-scale capsules allows protection of the payload f... more The encapsulation of payloads in micro- to nano-scale capsules allows protection of the payload from the surrounding environment and control of its release profile. Herein, we program the release of hydrophilic payloads from nanocontainers by co-encapsulating simple inorganic salts for adjusting the osmotic pressure. The latter either leads to a burst release at high concentrations of co-encapsulated salts or a sustained release at lower concentrations. Osmotic pressure causes swelling of the nanocapsule's shell and therefore sustained release profiles can be adjusted by crosslinking it. The approach presented allows for programing the release of payloads by co-encapsulating inexpensive salts inside nanocontainers without the help of stimuli-responsive materials.

Macromolecules, 1998

A poly(dimethylsiloxane)-co-poly(hydromethysiloxane) (PDMS-co-PHMS) polymer has been characterize... more A poly(dimethylsiloxane)-co-poly(hydromethysiloxane) (PDMS-co-PHMS) polymer has been characterized with respect to chain length distribution, heterogeneity of chemical composition, and sequence distribution using SEC, 1 H- and 29 Si NMR, and MALDI-TOF-MS. Due to ambiguities in the peak assignment the deconvolution of the mass spectrum into the bivariate copolymer distribution is not possible. Alternatively, the expected mass spectrum is computed from the SEC and NMR data. It is then mapped onto the measured one, and an almost perfect agreement is found within the peak resolved low molar mass range, leaving only a small number of adjustable parameters. As a result it could be shown that a large number of chains contain no functionalizable units at all.