Publikationen

Selenium sulfide, the active ingredient of traditional antidandruff shampoos, is industrially produced from selenium dioxide (SeO2) and hydrogen sulfide (H2S) under acidic conditions. This reaction can also be carried out with natural H2S and H2S generated by sulfate-reducing bacteria (SRB). These bacteria are robust and, by relying on their conventional growth medium, also thrive in “waste” materials, such as a mixture of cabbage juice and compost on the one side, and a mixture of spoiled milk and mineral water on the other. In these mixtures, SRB are able to utilize the DL-lactate and sulfate (SO42−) present naturally and produce up to 4.1 mM concentrations of H2S in the gas phase above a standard culture medium. This gas subsequently escapes the fermentation vessel and can be collected and reacted with SeO2 in a separate compartment, where it yields, for instance, pure selenium sulfide, therefore avoiding the need for any cumbersome workup or purification procedures. Thus “harvesting” H2S and similar (bio-)gases produced by the fermentation of organic waste materials by suitable microorganisms provides an elegant avenue to turn dirty waste into valuable clean chemical products of considerable industrial and pharmaceutical interest. © 2025 by the authors.

With rising demand for lithium-ion batteries, efficient recycling is crucial. While conventional methods face cost and environmental challenges, electrochemical recovery offers a sustainable and energy-efficient alternative. In this study, we investigate the electrochemical recovery of lithium-ions from spent lithium iron phosphate batteries using carbon-coated lithium iron phosphate electrodes, with a focus on the influence of pH adjustment and competing ion effects. Our results demonstrate that NaOH-adjusted electrolytes provide the highest lithium-ion recovery efficiency, with an average removal capacity of 18 mgLi gLFP−1 over 50 cycles. However, prolonged cycling leads to capacity fading, particularly in the presence of competing cations such as Na+ and K+, which impact lithium selectivity and electrode stability. These findings underscore the importance of optimizing electrolyte conditions and electrode materials to enhance long-term performance. Future research should explore alternative pH control strategies and scalable process designs to facilitate industrial implementation. Advancing electrochemical lithium-ion recovery aligns with broader sustainability goals, offering a viable route toward circular battery recycling and reduced environmental impact.

Water-induced transparency loss in styrene–butadiene block copolymers (SBCs) has been investigated under a variety of conditions. Consistent with earlier work on homopolymers, the opacity after prolonged water exposure is expected to be caused by water clustering, which results from stronger water–water than water–polymer interactions. The water clusters distort the surrounding polymer matrix, causing local changes in the refractive index. It was found that the hard phase has only a minor contribution to the transparency loss, while the rubbery phase appears to be the major contributor. However, the loss of transparency was found not to be directly proportional to the volume of the soft phase, and a significant effect of the block copolymer morphology was observed, which was confirmed by a series of transmission electron microscopy and SAXS measurements. This effect is particularly evident in the transition from a continuous hard phase through a co-continuous morphology to a continuous soft phase. The acquired insights were subsequently used to predict long-term optical performance in SBCs to provide a tool in product development. Loss of transparency predictions was proven to be adequate through a classical regression-extrapolation approach using a limited data set, accurately simulating performance beyond 2600 h exposure time using only 600 h of measurement time. Additionally, it was shown that artificial neural networks could provide a solid tool in predicting performance even prior to synthesis, granted that the selection of descriptors is complete and the appropriate amount of data is supplied with a proper spread over the descriptor space.

Lithium–sulfur batteries (Li–S), controlled by the sulfur cathode’s conversion reaction, are a promising technology due to their high theoretical capacities and the sustainability of sulfur. In contrast to commercially available lithium-ion cathodes, the Li–S system still suffers from unstable cycling performance due to the diffusion of soluble polysulfides out of the cathode. This study explored sulfur cathodes with varying pore sizes, mainly in the micropore regime (<2 nm). We conducted the work using carbonate-based and ether-based electrolytes to investigate the impact of the cathode/solid electrolyte interphase on the cycling performance of the battery. By infiltrating the carbon with different C/S ratios, we found that the maximum sulfur infiltration attained was 61 mass % with a C/S ratio of 1:1.5. The best sulfur utilization and cycling performance were achieved with carbonate electrolyte and 50 mass % S in carbon with a specific surface area of 2210 m2/g and a total pore volume of 1.20 cm3/g. Our findings emphasize the importance of designing cathodes with optimized pore structures to balance sulfur accommodation, minimize sulfur dissolution, and mitigate capacity degradation.

Neutrophils are innate immune cells that perpetually patrol the circulation and tissues. They sense and migrate toward invading microbes to initiate and orchestrate a robust immune response. Their highly reactive nature, driven by multiple and redundant receptor families recognizing bacterial components, makes them particularly sensitive to contaminants or nonsterile implants. This often leads to a neutrophil-driven foreign body reaction that shields the implant and triggers inflammation, collateral tissue damage, or even sepsis. This presents a significant challenge for living therapeutic materials, an innovative biomedical approach using genetically engineered bacteria encapsulated in natural or synthetic polymers. Since bacterial turnover inevitably releases pathogen-associated molecular patterns that activate neutrophils to mitigate or prevent a potent neutrophil response, living therapeutic material design strategies are required to protect the living therapeutic material from damage while maintaining its functionality. This review focuses on current strategies involving bacterial genetic engineering, immune-shielding materials and factors, and modified hydrogel-based systems to minimize immune recognition. Engineering the bacterial chassis to produce immune tolerance–inducing metabolites from commensals, modified pathogen-associated molecular patterns, and pathogen-associated molecular pattern–cleaving autolysins may enhance biocompatibility. A crucial aspect for clinical translation is robust biocontainment to prevent bacterial escape, ensuring living therapeutic material remains a safe and effective therapeutic platform. While the potential of the living therapeutic material concept lies in the development of tailored medicine specifically designed for a specific disease and enabling local, cost-effective, site- and stimulus-responsive treatment, balancing the neutrophil immune response remains an important milestone on the path to living therapeutic material for future biomedical applications.

Formyl peptide receptors (FPRs) are pattern recognition receptors well-known for bacterial pathogen sensing. We here identified activator and inhibitor motifs for FPRs that are present on surface proteins of various viral pathogens. Peptides containing these motifs interact with all FPR family members and modulate various important immune functions in innate immune cells. Viral breakdown products comprising these motifs were found in patients with COVID-19. In the spike protein, many activators are found in highly mutagenic regions, whereas the inhibitor motif is located in a conserved domain that also exists in further unrelated viruses. The physiochemical properties of FPR1 activators correlate with the occurrence of protein aggregation hotspots. Such hotspots are present on various surface proteins of unrelated viruses that can also activate FPRs. This points toward a general contribution of FPRs in modulating antiviral immune responses during many distinct viral infections.

The persistent accumulation of plastic waste, particularly polystyrene (PS), poses significant environmental challenges because of its extensive use and low recycling rates. Addressing these challenges necessitates innovative and sustainable solutions. This study presents a strategy to upcycle PS waste into valuable chemical products, including adipic acid, hexanediol, hexamethylenediamine, and nylon-6,6, using metabolically engineered Pseudomonas putida KT2440. This process involves the photolytic degradation of PS into benzoic acid, followed by microbial conversion into cis,cis-muconate (MA) and chemical synthesis of the final products. The engineered strains withstood 30 mM concentrations of PS-derived aromatics and converted them stoichiometrically into MA in the presence of glucose as a growth substrate. 13C metabolic flux analysis revealed energy and redox limitations in the presence of 25 mM benzoate and 300 mM MA. The cells responded to stress by enhancing the flux for periplasmic glucose oxidation and fluxes through the NADPH-forming dehydrogenases; this process caused more than 40 % glucose‑carbon loss into byproducts. Fine-tuned dynamic glucose and benzoate feeding enabled high-level MA production. Energy-optimized genome-reduced strains were used to increase carbon efficiency. A final MA titer of over 65 g L−1 was achieved in fed-batch fermentation. This process was demonstrated using the glucose derived from a viscose textile waste blend as the growth substrate and resulted in fully waste-based products. The resulting adipic acid and hexamethylenediamine were polymerized into nylon-6,6 with properties comparable to those of petrochemical-derived polymers, revealing a sustainable pathway for PS upcycling. This research provides a proof-of-concept for bacterial upgrading of PS-derived substrates and a viable method for managing plastic waste and producing valuable chemical products.

Living microbial therapeutics promise precise, programmable interventions at disease sites, yet most demonstrations of on demand drug release still rely on Escherichia coli, whose rich genetic toolkit is unmatched among probiotics. In particular, genetic parts to regulate in situ protein production are severely lacking in non-model probiotic bacteria like lactobacilli. Here, we equip the probiotic Lactiplantibacillus plantarum with high-performance genetic switches and show how material encapsulation can further enhance their behavior. By integrating cumate or vanillate-responsive operators and repressors with the strongest constitutive promoter in L. plantarum (Ptec), we generated two switches that support micromolar range induction. In rapidly growing culture conditions, acidification-associated leakiness of the switch was observed, which could compromise their applicability for precise on-demand delivery of drugs. Furthermore, such leakiness also limits the duration for which these engineered probiotics can be reliably used. By restricting growth through mild temperature or nutrient limitation, acidification and leakiness were suppressed. Strikingly, immobilizing the engineered cells in core-shell alginate beads (Protein Eluting Alginate with Recombinant Lactobacilli, PEARLs) almost eliminated leakiness, enabling day-scale, reversible control of intracellular reporters and secreted enzymes. This leakiness suppression persisted when two strains carrying orthogonal switches were co-encapsulated and even after miniaturization to submillimeter beads. These results expand the genetic toolbox of probiotic L. plantarum, demonstrate the synergy between genetic circuit design and material encapsulation, and advance lactobacilli toward stimuli-responsive therapeutic platforms.

Natural killer (NK) cells are critical components of the first-line immune defense, responsible for eliminating tumorigenic cells. NK cell-based adoptive immunotherapy has gained increasing attention; however, cryopreservation, a standard technique for NK cell storage, significantly impairs NK cell cytotoxicity, particularly in physiological 3D environments. Here, we demonstrate that short-term co-culture with effector T cells markedly enhances NK cell motility and killing functionality. Notably, a brief 1-day co-culture is sufficient to restore cryopreservation-impaired NK cell functionality in 3D environments. This enhancement requires direct contact between T cells and NK cells, which facilitates localized high concentrations of IL-2 at the cell contact sites. To develop a controled, donor-independent solution, we demonstrate that synthetic T cells with surface-bound IL-2 exhibit superior efficiency in revitalizing cryopreserved NK cells. These findings uncover a previously unrecognized role for physical contact-mediated local IL-2 signaling and provide an efficient, cost-effective, and tunable strategy to rescue NK cell functionality post-cryopreservation, paving the way for more scalable, potent, and clinically viable NK cell-based immunotherapies.

Understanding how nanoparticles form stable colloids is fundamental to their practical applications. Nonlinear ligands are known to increase the stability of nanoparticles in apolar solvents compared to shells of linear alkyl chains. Here, we reveal the molecular origin of this colloidal stability. We observe that even a single methyl side chain can suppress disorder–order transitions in the ligand shell, with double bonds or branches leading to drastic decreases in agglomeration temperature in such dispersions. Through a combination of temperature-dependent X-ray scattering and molecular dynamics simulations, we show that these simple structural modifications prevent ligand molecules from forming ordered bundles, maintaining shell disorder even at temperatures approaching solvent freezing. The absence of ligand order enhances colloidal stability by weakening attraction between the ligand shells via a combination of energetic and entropic factors. This mechanism extends dispersion stability by more than 100 K compared to linear ligands of equivalent length. Our findings provide a molecular-level explanation for the enhanced stability previously observed with branched and unsaturated ligands, offering an effective strategy for engineering nanoparticle dispersions that remain stable across broad temperature ranges.