Publikationen

The treatment of Parkinson’s disease has been moving into the focus of pharmaceutical development. Yet, the necessity for reliable model systems in the development phase has made research challenging and in vivo models necessary. We have established reliable, reproducible in vitro model systems to evaluate the binding and transport of dopamine-loaded PLGA nanoparticles for the treatment of Parkinson’s disease and put the results in context with comparable in vivo results. The in vitro models have provided similar results concerning the usability of the investigated nanoparticles as the previously used in vivo models and thus provide a good alternative in line with the 3R principles in pharmaceutical research.

Recycling of Waste from Electrical and Electronic Equipment (WEEE) is crucial in preventing resource depletion and promoting a circular economy. The increasing fraction of printed and in-mold electronics is particularly challenging. The combinations of polymers and printed metals are difficult to disassemble due to the strong interfaces that are formed to create reliable in-mold devices. The relatively low metal content makes recycling uneconomical and those valuable materials are then lost to landfill or incineration. Separation layers enable design-for-recycling with minimal modifications during the fabrication process, while preserving product performance and reliability. We present a scalable method for preparing polymer separation layers for printed and in-mold electronics. Slot-die coating is used to prepare water-soluble polymer films with a dry thickness of less than 10 μm on commodity polymer substrates. This separation layer improves the bending stability of inkjet- and screen-printed circuits. Furthermore, it is compatible with typical polymer processing methods, such as thermoforming and injection molding. Various methods, including plasma treatment, are presented to ensure adhesion of the modified interfaces. Finally, we investigate the material recovery and demonstrate the release of the integrated metal within a few minutes by dissolving the separation layer in water. This material recovery process can be readily integrated into current WEEE recycling processes.

We explore the potential of nanocrystals (a term used equivalently to nanoparticles) as building blocks for nanomaterials, and the current advances and open challenges for fundamental science developments and applications. Nanocrystal assemblies are inherently multiscale, and the generation of revolutionary material properties requires a precise understanding of the relationship between structure and function, the former being determined by classical effects and the latter often by quantum effects. With an emphasis on theory and computation, we discuss challenges that hamper current assembly strategies and to what extent nanocrystal assemblies represent thermodynamic equilibrium or kinetically trapped metastable states. We also examine dynamic effects and optimization of assembly protocols. Finally, we discuss promising material functions and examples of their realization with nanocrystal assemblies.

We undertake a numerical study of the ordering kinetics in the two-dimensional (2d) active Ising model (AIM), a discrete flocking model with a non-conserved scalar order parameter. We find that for a quench into the liquid-gas coexistence region and in the ordered liquid region, the characteristic length scale of both the density and magnetization domains follows the Lifshitz-Cahn-Allen (LCA) growth law: R(t)∼t1/2, consistent with the growth law of passive systems with scalar order parameter and non-conserved dynamics. The system morphology is analyzed with the two-point correlation function and its Fourier transform, the structure factor, which conforms to the well-known Porod's law, a manifestation of the coarsening of compact domains with smooth boundaries. We also find the domain growth exponent unaffected by different noise strengths and self-propulsion velocities of the active particles. However, transverse diffusion is found to play the most significant role in the growth kinetics of the AIM. We extract the same growth exponent by solving the hydrodynamic equations of the AIM.

Microfluidics plays a pivotal role in organ-on-chip technologies and in the study of synthetic cells, especially in the development and analysis of artificial cell models. However, approaches that use synthetic cells as integral functional components for microfluidic systems to shape the microenvironment of natural living cells cultured on-chip are not explored. Here, colloidosome-based synthetic cells are integrated into 3D microfluidic devices, pioneering the concept of synthetic cell-based microenvironments for organs-on-chip. Methods are devised to create dense and stable networks of silica colloidosomes, enveloped by supported lipid bilayers, within microfluidic channels. These networks promote receptor-ligand interactions with on-chip cultured cells. Furthermore, a technique is introduced for the controlled release of growth factors from the synthetic cells into the channels, using a calcium alginate-based hydrogel formation within the colloidosomes. To demonstrate the potential of the technology, a modular plug-and-play lymph-node-on-a-chip prototype that guides the expansion of primary human T cells by stimulating receptor ligands on the T cells and modulating their cytokine environment is presented. This integration of synthetic cells into microfluidic systems offers a new direction for organ-on-chip technologies and suggests further avenues for exploration in potential therapeutic applications.

Dr. Helmut Cölfen, an exceptional interdisciplinary scientist, mentor, colleague, and dear friend, passed away in November 2023 at the age of 58. His untimely departure is a profound loss for the fields of analytical ultracentrifugation, colloid, crystallization, and polymer research. This obituary pays tribute to Helmut, honoring his remarkable academic career and contributions to the study of nanochemistry, biophysics, and life sciences. Helmut was renowned for his pioneering research contributions in several key research areas: (1) Development of advanced analytical techniques: Helmut made major contributions to techniques such as analytical ultracentrifugation and field flow fractionation, which are widely utilized to characterize the structure of biomolecules and the growth of nanostructured crystalline materials; (2) Study of nucleation and crystallization processes: Helmut explored the early stages of crystallization which led to the discovery of pre-nucleation clusters and mesocrystal intermediates, in the presence of additives and templates; and (3) Investigation of structure and morphogenesis of mesocrystals, examining their molecular properties.

The tailored synthesis of copolymer architectures provides insights into fundamental structure–property relationships for the formation of complex morphologies through microphase separation. In this way, classical areas within the phase diagram can be specifically influenced and also adapted for important applications. The exploration of copolymer architectures also offers the possibility to discover entirely new morphologies. In this study, we design a symmetric dendrimer-like second generation block copolymer by anionic polymerization. The structural design of the polymers influences the curvature of the interfaces to produce, in particular, bicontinuous morphologies and is investigated based on molecular chain architecture. After extensive molecular analysis of the new dendrimer-like block copolymers, the resulting morphology is analyzed using transmission electron microscopy, atomic force microscopy, and small-angle X-ray scattering measurements. We further combine the experimentally obtained morphologies with Monte Carlo simulations to better understand the relationship between tailored polymer architecture and the observed morphology. By changing the volume ratio of the copolymers used and also mixing this complex polymer architecture with a linear block copolymer, we gain insights into the polymer behavior at the phase boundaries. This knowledge has an impact on the optical and mechanical properties of thermoplastic elastomers and their corresponding blends.

Developing thin, freestanding electrodes that work simultaneously as a current collector and electroactive material is pivotal to integrating portable and wearable chemical sensors. Herein, we have synthesized graphene/Prussian blue (PB) electrodes for hydrogen peroxide detection (H2O2) using a two-step method. First, an reduced graphene oxide/PAni/Fe2O3 freestanding film is prepared using a doctor blade technique, followed by the electrochemical deposition of PB nanoparticles over the films. The iron oxide nanoparticles work as the iron source for the heterogeneous electrochemical deposition of the nanoparticles in a ferricyanide solution. The size of the PB cubes electrodeposited over the graphene-based electrodes was controlled by the number of voltammetric cycles. For H2O2 sensing, the PB10 electrode achieved the lowest detection and quantification limits, 2.00 and 7.00 μM, respectively. The findings herein evidence the balance between the structure of the graphene/PB-based electrodes with the electrochemical performance for H2O2 detection and pave the path for developing new freestanding electrodes for chemical sensors.

The unsustainable dependence of nitrogen fertilizers (NFs) production on energy-intensive processes and its association with nitrate-laden wastewater that fuels harmful algal blooms (HABs) necessitate innovative solutions. Here, we propose a paradigm shift: repurposing HABs biomass as carbon-based catalysts (Cu1Mo1/NC) for the ambient-condition electrosynthesis of NFs from NO3− and CO2. Remarkably, Cu1Mo1/NC delivers a high NFs yield rate of 2303 μg h−1 mgcat−1 (772 μg h−1mgcat−1 for urea and 1531 μg h−1 mgcat−1 for ammonia) with a Faradaic efficiency (FE) of 68.4% (15.2% for urea and 53.2% for ammonia) at −1.05 V vs. RHE. Experimental and theoretical evidence reveal that Cu doping tunes the d-band center of Cu1Mo1/NC, bringing it closer to the Fermi level. This enhances the intermediate adsorption, thereby propelling the C-N coupling reaction. Carbon reduction potential analysis underscores the promising feasibility and sustainable value of the presented method.

Herein, we report polyphosphonate covalent organic frameworks (COFs) constructed via P-O-P linkages. The materials are synthesized via a single-step condensation reaction of the charge-assisted hydrogen-bonded organic framework, which is constructed from phenylphosphonic acid and 5,10,15,20‐tetrakis[p‐phenylphosphonic acid]porphyrin and is formed by simply heating its hydrogen-bonded precursor without using chemical reagents. Above 210 °C, it becomes an amorphous microporous polymeric structure due to the oligomerization of P-O-P bonds, which could be shown by constant-time solid-state double-quantum 31P nuclear magnetic resonance experiments. The polyphosphonate COF exhibits good water and water vapor stability during the gas sorption measurements, and electrochemical stability in 0.5 M Na2SO4 electrolyte in water. The reported family of COFs fills a significant gap in the literature by providing stable microporous COFs suitable for use in water and electrolytes. Additionally, we provide a sustainable synthesis route for the COF synthesis. The narrow pores of the COF effectively capture CO2.