The Leibniz Institute of Polymer Research Dresden in Dresden (German: Leibniz-Institut für Polymerforschung) – in short IPF Dresden – is a non-university research institute and a member of the Gottfried Wilhelm Leibniz Scientific Community. The IPF is carrying out fundamental as well as application-oriented research in all areas of polymer science and investigates polymer materials with new or improved characteristics. In the material development, emphasis is given to nanotechnological aspects as well as to biosystem interfaces.
Thin films of auto-oxidized dopamine, the so-called polydopamine (PDA), have been introduced as universal bioinspired "green" adhesion promoter for a variety of applications. This study investigates the effect of different alkaline solutions on PDA films on polyethylene fibers over a time ranging from 1 h to 67 days. On one hand, this supports the application of adhesive PDA films in alkaline media such as cementitious matrices. On the other hand, a controlled chemical decomposition or degradation can be used to reverse adhesion and separate the components of PDA-mediated composite materials for re-use and recycling. The effect of the surface modification and the alkaline treatments was studied using atomic force microscopy, electrokinetic measurements, and spectroscopic techniques. Depending on the composition of the alkaline solution, a progressive dissolution or depolymerization of PDA aggregates was observed. Zeta potential measurements detected, however, acidic groups on the fiber surface even after alkaline treatment for 67 days, indicating that the PDA film was not fully removed.
The origin of life remains a scientific mystery, particularly the emergence of protocells. One hypothesis proposes that protocells arose as droplets formed via liquid-liquid phase separation of polymers. The work on this hypothesis leaves open how protocells survived in fluctuating or cyclic environments. We consider a model system incorporating both spontaneous polymerization and droplet-facilitated fuel-driven polymerization. We show that the resulting droplets display a stationary hysteresis with respect to available fuel. Droplets can remain stable even after the fuel-driven polymerization reactions significantly diminish, suggesting a potential mechanism for protocell formation and resilience to environmental fluctuations. This robustness would have enabled protocells to endure early environmental challenges, such as energy shortages in a famine.
Precise mapping of structural heterogeneity at the sub-10 nm scale is pivotal for rational nanoparticle design, yet conventional analytical workflows remain inadequate. Here we integrate dilution-controlled asymmetric flow field-flow fractionation (AF4) with small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) to interrogate ellipsoidal solid-liquid lipid nanoparticles (LNPs). The dilution-controlled AF4 mode amplifies scattering contrast, enabling robust, shape-resolved analysis across entire elution profiles. Coupling AF4 to SANS in D2O further sharpens resolution for the smallest fractions by reducing particle diffusion through increased solvent viscosity. Comparative sizing shows that SAXS/SANS accurately capture primary particles down to ∼5 nm, whereas multi-angle light scattering chiefly detects loosely associated aggregates. Morphology profiling reveals that surfactant identity governs particle shape, polydispersity, and overall architecture. Joint SAXS/SANS modeling uncovers a 2-3 nm polar shell enveloping an internal core-shell morphology. Together, these insights refine our understanding of LNP size, morphology and drug localization and establish dilution-controlled AF4-SAXS/SANS as a high-resolution platform for dissecting complex nanoparticle systems relevant to biomedical applications.
The development of effective drug delivery systems for subcutaneous or intradermal injection requires systems with improved bioavailability and biocompatibility. Systematic physicochemical and biological interrogation of carnauba-wax/red-palm-oil lipid nanoparticles (LNPs) stabilized with d-α-tocopheryl-PEG-1000-succinate and polysorbate-40 shows that purposeful matrix engineering yields a robust sub-50 nm carrier for under-skin delivery. Cryo-TEM and SAXS reveal hybrid morphology dominated by 30-40 nm toroidal disc-shaped particles. Orthogonal analytics via multidetection asymmetrical flow field-flow fractionation and WAXS confirm that loading with quinine or dihydroartemisinin leaves size and crystallinity unchanged, achieving approximately 90% encapsulation efficiencies and particle stability up to 18 months at 4°C. Formulations containing red palm oil and the dual-surfactant corona exhibited reduced size dispersity compared with single-component formulations. Long-term viability assays in primary human fibroblasts and macrophages, and ex vivo cultured human skin, underscore excellent biocompatibility up to 0.024% (w/v) lipid. Fluorescein-labeled LNPs traversed the dermis and hypodermis, while only nanomolar lipid concentrations appeared in the receiver medium, indicating a sustained local depot. Overall, this study provides insights into the relationship between formulation composition, particle morphology and measured physicochemical and biological properties relevant to under-skin administration.
