Publikationen

Surface-grafted polymers can reduce friction between solids in liquids by compensating the normal load with osmotic pressure, but they can also contribute to friction when fluctuating polymers entangle with the sliding counter face. We have measured forces acting on a single fluctuating double-stranded DNA polymer, which is attached to the tip of an atomic force microscope and interacts intermittently with nanometer-scale methylated pores of a self-assembled polystyrene-block-poly(4-vinylpyridine) membrane. Rare binding of the polymer into the pores is followed by a stretching of the polymer between the laterally moving tip and the surface and by a force-induced detachment. We present results for the velocity dependence of detachment forces and of attachment frequency and discuss them in terms of rare excursions of the polymer beyond its equilibrium configuration.

Synthetic biology applies concepts from electrical engineering and information processing to endow cells with computational functionality. Transferring the underlying molecular components into materials and wiring them according to topologies inspired by electronic circuit boards has yielded materials systems that perform selected computational operations. However, the limited functionality of available building blocks is restricting the implementation of advanced information-processing circuits into materials. Here, a set of protease-based biohybrid modules the bioactivity of which can either be induced or inhibited is engineered. Guided by a quantitative mathematical model and following a design-build-test-learn (DBTL) cycle, the modules are wired according to circuit topologies inspired by electronic signal decoders, a fundamental motif in information processing. A 2-input/4-output binary decoder for the detection of two small molecules in a material framework that can perform regulated outputs in form of distinct protease activities is designed. The here demonstrated smart material system is strongly modular and can be used for biomolecular information processing for example in advanced biosensing or drug delivery applications.

Osteoporosis is a silent bone disease and a growing health issue. Despite recent progress in diagnosis and treatment, effective therapeutic strategies are still needed. One of the possible solutions is the implantation of engineered drug-releasing scaffolds at the disease site. To boost this approach further, we aimed to develop printable materials (the inks) for the construction of patient-specific 3D scaffolds with drug-release capability. The inks were composed of chitosan – a natural osteoinductive polysaccharide, nanohydroxyapatite – a natural bone matrix ingredient improving mechanical properties, sodium alendronate – a bioactive drug, and hydroxyethyl-cellulose – a filler improving the printability. Printed scaffolds were crosslinked with citric acid or KOH. After coating with collagen and gelatin, they demonstrated biocompatibility with the adipose-derived mesenchymal stem cells and MG-63 cell line. They also showed a sustained release of alendronate for 50 days, causing a significant reduction in the expression of Cathepsin K, an osteoclast-specific gene marker, which indicates the osteoclast-inhibiting capacity of the coated scaffolds. This work demonstrates the potential of developed printable materials to find applications as cell and drug carriers for the treatment of osteoporosis.

Probiotic bacteria, such as Lactobacilli, have been shown to elicit beneficial effects in various tissue regeneration applications. However, their formulation as living bacteria is challenging, and their therapeutic use as proliferating microorganisms is especially limited in immunocompromised patients. Here, we propose a new therapeutic avenue to circumvent these shortcomings by developing a bacteriomimetic hydrogel based on membrane vesicles (MVs) produced by Lactobacilli. We coupled MVs from Lactobacillus plantarum and Lactobacillus casei, respectively, to the surface of synthetic microparticles, and embedded those bacteriomimetics into a pharmaceutically applicable hydrogel matrix. The wound microenvironment changes during the wound healing process, including adaptions of the pH and changes of the oxygen supply. We thus performed proteomic characterization of the MVs harvested under different culture conditions and identified characteristic proteins related to the biological effect of the probiotics in every culture state. In addition, we highlight a number of unique proteins expressed and sorted into the MVs for every culture condition. Using different in vitro models, we demonstrated that increased cell migration and anti-inflammatory effects of the bacteriomimetic microparticles were dependent on the culture condition of the secreting bacteria. Finally, we demonstrated the bacteriomimetic hydrogel's ability to improve healing in an in vivo mouse full-thickness wound model. Our results create a solid basis for the future application of probiotic-derived vesicles in the treatment of inflammatory dispositions and stimulates the initiation of further preclinical trials.

The addition of water to native cellulose/1-ethyl-3-methylimidazolium acetate solutions catalyzes the formation of gels, where polymer chain–chain intermolecular associations act as cross-links. However, the relationship between water content (Wc), polymer concentration (Cp), and gel strength is still missing. This study provides the fundamentals to design water-induced gels. First, the sol–gel transition occurs exclusively in entangled solutions, while in unentangled ones, intramolecular associations hamper interchain cross-linking, preventing the gel formation. In entangled systems, the addition of water has a dual impact: at low water concentrations, the gel modulus is water-independent and controlled by entanglements. As water increases, more cross-links per chain than entanglements emerge, causing the modulus of the gel to scale as Gp ∼ Cp2Wc3.0±0.2. Immersing the solutions in water yields hydrogels with noncrystalline, aggregate-rich structures. Such water–ionic liquid exchange is examined via Raman, FTIR, and WAXS. Our findings provide avenues for designing biogels with desired rheological properties.

The laser welding of Cu–Al alloys for battery applications in the automotive industry presents significant challenges due to the high reflectivity of copper. Inadequate bonding and low mechanical strength may occur when the laser radiation is directed toward the copper side in an overlap configuration welding. To tackle these challenges, a laser surface treatment technique is implemented to enhance the absorption characteristics and overcome the reflective nature of the copper material. However, elevating the surface roughness and heat-energy input over threshold values leads to heightened temperature and extreme weld. This phenomenon escalates the formation of detrimental intermetallic compounds (IMC), creating defects like cracks and porosity. Metallurgical analysis, which is time-consuming and expensive, is usually used in studies to detect these phases and defects. However, to comprehensively evaluate the weld quality and discern the impact of surface structure, adopting a more innovative approach that replaces conventional cross-sectional metallography is essential. This article proposes a model based on the image feature extraction of the welds to study the effect of the laser-based structure and the other laser parameters. It can detect defects and identify the weld quality by weld classification. However, due to the complexity of the photo features, the system requires image processing and a convolutional neural network (CNN). Results show that the predictive model based on trained data can detect different weld categories and recognize unstable welds. The project aims to use a monitoring model to guarantee optimized and high-quality weld series production. To achieve this, a deeper study of the parameters and the microstructure of the weld is utilized, and the CNN model analyzes the features of 1310 pieces of weld photos with different weld parameters.

Glioblastoma (GB) is the most common and aggressive brain tumor. The treatment for newly diagnosed glioblastoma is surgical resection of the primary tumor mass, followed by radiotherapy and chemotherapy. However, recurrences frequently occur in proximity to the surgical resection area. In these cases, none of the current therapies is effective. Recently, implantable biomaterials seem to be a promising strategy against GB recurrence. Here, for the first time we combined the tailorable properties of soy-protein hydrogels with the versatility of drug-loaded liposomes to realize a hybrid biomaterial for controlled and sustained nanoparticles release. Hydrogel consisting of 18–20 % w/v soy-protein isolated were fabricated in absence of chemical cross-linkers. They were biodegradable (−10 % and −30 % of weight by hydrolytic and enzymatic degradation, respectively in 3 days), biocompatible (>95 % of cell viability after treatment), and capable of sustained release of intact doxorubicin-loaded liposomes (diffusion coefficient between 10−18 and 10 −19 m2 s−1). A proof-of-concept in a “donut-like” 3D-bioprinted model shows that liposomes released by hydrogels were able to diffuse in a model with a complex extracellular matrix-like network and a 3D structural organization, targeting glioblastoma cells.The combination of nanoparticles' encapsulation capabilities with the hydrogels' structural support and controlled release properties will provide a powerful tool with high clinical relevance that could be applicable for the treatment of other cancers, realizing patient-specific interventions.

The increasing prevalence of dry eye syndrome in aging and digital societies compromises long-term contact lens (CL) wear and forces users to regular eye drop instillation to alleviate discomfort. Here a novel approach with the potential to improve and extend the lubrication properties of CLs is presented. This is achieved by embedding lubricant-secreting biofactories within the CL material. The self-replenishable reservoirs autonomously produce and release hyaluronic acid (HA), a natural lubrication and wetting agent, long term. The hydrogel matrix regulates the growth of the biofactories and the HA production, and allows the diffusion of nutrients and HA for at least 3 weeks. The continuous release of HA sustainably reduces the friction coefficient of the CL surface. A self-lubricating CL prototype is presented, where the functional biofactories are contained in a functional ring at the lens periphery, outside of the vision area. The device is cytocompatible and fulfils physicochemical requirements of commercial CLs. The fabrication process is compatible with current manufacturing processes of CLs for vision correction. It is envisioned that the durable-by-design approach in living CL could enable long-term wear comfort for CL users and minimize the need for lubricating eye drops.

An important challenge in active matter lies in harnessing useful global work from entities that produce work locally, e.g., via self-propulsion. We investigate here the active matter version of a classical capillary rise effect, by considering a non-phase separated sediment of self-propelled Janus colloids in contact with a vertical wall. We provide experimental evidence of an unexpected and dynamic adsorption layer at the wall. Additionally, we develop a complementary numerical model that recapitulates the experimental observations. We show that an adhesive and aligning wall enhances the pre-existing polarity heterogeneity within the bulk, enabling polar active particles to climb up a wall against gravity, effectively powering a global flux. Such steady-state flux has no equivalent in a passive wetting layer.

Molecular optogenetics utilizes genetically encoded, light-responsive protein switches to control the function of molecular processes. Over the last two years, there have been notable advances in the development of novel optogenetic switches, their utilization in elucidating intricate signaling pathways, and their progress toward practical applications in biotechnological processes, material sciences, and therapeutic applications. In this review, we discuss these areas, offer insights into recent developments, and contemplate future directions.