Engineered microbial living matter for diagnostics, prevention, and therapy

Living therapeutic and diagnostic materials based on engineered microorganisms are emerging as a novel approach with the perspective of providing patient-tailored, sustainable, and cost-effective healthcare solutions. In this review, we focus on recent advances in using genetically or chemically engineered microorganisms as living diagnostics, therapeutics, and as a means of prevention for various diseases. We also highlight the applications of living therapeutics for acute and chronic diseases, and the role of micro/macro-encapsulation of the engineered microorganisms. We further showcase the current success of engineered living therapeutics in clinical trials and discuss challenges and future trends in the field

Optogenetic control of pheromone gradients and mating behavior in budding yeast

During mating in budding yeast, cells use pheromones to locate each other and fuse. This model system has shaped our current understanding of signal transduction and cell polarization in response to extracellular signals. The cell populations producing extracellular signal landscapes themselves are, however, less well understood, yet crucial for functionally testing quantitative models of cell polarization and for controlling cell behavior through bioengineering approaches. Here we engineered optogenetic control of pheromone landscapes in mating populations of budding yeast, hijacking the mating-pheromone pathway to achieve spatial control of growth, cell morphology, cell-cell fusion, and distance-dependent gene expression in response to light. Using our tool, we were able to spatially control and shape pheromone gradients, allowing the use of a biophysical model to infer the properties of large-scale gradients generated by mating populations in a single, quantitative experimental setup, predicting that the shape of such gradients depends quantitatively on population parameters. Spatial optogenetic control of diffusible signals and their degradation provides a controllable signaling environment for engineering artificial communication and cell-fate systems in gel-embedded cell populations without the need for physical manipulation

Direct monitoring of intracellular polymer degradation via BODIPY dynamic dequenching

Biodegradable polymers play a crucial role in biomedical applications, particularly as nanocarriers in drug delivery. While labeling the polymers with fluorescent dyes facilitates monitoring their biodistribution and post cellular uptake, tracking polymer degradation within biological systems remains a challenge. This raises important unanswered questions regarding the fate of the polymers, their degradation products, and the degree of their degradation within biological systems. In this study, we developed a novel dynamic biodynamer (BDP-Lys) composed of BODIPY and lysine-hydrazide monomers linked by reversible dynamic covalent bonds, designed to control the fluorescence of BODIPY by degradation. The BDP-Lys undergoes pH-responsive degradation, leading to recovery of quenched BODIPY and enhanced fluorescence emissions, thereby enabling direct monitoring of intracellular polymer degradation. Physicochemical characterization revealed its molecular weight, filament-like morphology, and a notable 12-fold increase in fluorescence intensity at acid-induced degradation. In vitro studies demonstrated excellent biocompatibility, efficient cellular uptake and a threefold increase in fluorescence due to polymer degradation in mammalian cells, resulting in a maximum of 17 % monomer release in the first 24 h. Thus, BDP-Lys emerges as a promising tool for exploring polymer behavior in biological systems, providing real-time insights into degradation and offering new opportunities to address unresolved questions in the field

Toward the development of a specific non-enzymatic amperometric sensor for determining uric acid in fermentation samples

The development is proposed of a specific non-enzymatic amperometric sensor based on electrodeposited copper nanoparticles (Cu-NPs) for the determination of uric acid (UA) in fermentation samples. Through optimization of the Cu-NPs-containing sensing layer, it was demonstrated that copper(II)-induced oxidation (catalytic effect) in the presence of molecular oxygen is more effective for determining UA than the adsorption of UA on Cu and Cu-oxide surfaces. More importantly, simply changing the sensing layer’s surface chemistry by increasing the defect CuxOy on the surface of Cu-NPs after heating at 70 °C for only 20 min significantly improved the specificity of UA determination in both model and real fermentation samples (viz. supernatants of S. cerevisiae and E. coli). This study can be used as a guideline for the future assembly of functional electrodeposited sensing layers for the specific determination of target electroactive bioanalyte(s)

Segmented, Side-Emitting Hydrogel Optical Fibers for Multimaterial Extrusion Printing

Side-emitting optical fibers allow light to be deliberately outcoupled along the fiber. Introducing a customized side-emission profile requires modulation of the guiding and emitting properties along the fiber length, which is a particular challenge in continuous processing of soft waveguides. In this work, it is demonstrated that multimaterial extrusion printing can generate hydrogel optical fibers with tailored segments for light-side emission. The fibers are based on diacrylated Pluronic F-127 (PluDA). 1 mm diameter fibers are printed with segments of different optical properties by switching between a PluDA waveguiding ink and a PluDA scattering ink containing nanoparticles. The method allows the fabrication of fibers with segment lengths below 500 microns in a continuous process. The length of the segments is tailored by varying the switching time between inks during printing. Fibers with customized side-emission profiles along their length are presented. The functionality of the printed fibers is demonstrated by exciting fluorescence inside a surrounding 3D hydrogel. The presented technology and material combination allow unprecedented flexibility for designing soft optical fibers with customizable optical properties using simple processes and a medical material. This approach can be of interest to improve illumination inside tissues for photodynamic therapy (PDT)

Impact of Humidity on Water Dynamics and Electrical Conductivity in PEDOT:PSS/Cellulose Nanofibril Nanocomposite Films: Insights from Quasi-Elastic Neutron Scattering

The water dynamics in a nanocomposite film that consists of the electrically conductive poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and cellulose nanofibrils (CNFs) have been investigated during three cycles of exposure to low and high relative humidity (RH = 5% and 85%, respectively) using quasi-elastic neutron scattering (QENS). The obtained dynamical structure factors are transformed into the imaginary part of the dynamic susceptibility to better differentiate between the individual relaxation processes. In a humid environment, two different water species are present inside the films: fast-moving bulk water and slow-moving hydration water. During the first cycle, a large amount of hydration water enhances the polymer chain mobility, eventually leading to irreversible structural rearrangements within the film. In the subsequent cycles, we observed a release of all bulk water and portions of hydration water upon drying, along with an uptake of both water species in a humid environment. The relaxation times of hydration water diffusion as a function of momentum transfer can be described by a jump-diffusion model. The obtained jump lengths, residence times, and diffusion coefficients of hydration water suggest a change in the hydration layer upon drying: water molecules around hydrophobic groups are released from the film, while the hydrogen bonds between water and hydrophilic groups are sufficiently strong to keep these molecules inside the films, even in a dry state. The QENS results can be correlated to the structural and conductive properties. In the dry state, the low hydration water content and the absence of bulk water allow for improved wetting of the CNFs by PEDOT:PSS, which eventually increases the electrical conductivity of the films

Annual report 2024 / Leibniz Institute for New Materials

Das INM blickt auf ein besonderes Jahr 2024 zurück. Wissenschaftliche Highlights wie die Entwicklung einer selbst-befeuchtenden Kontaktlinse gegen das Trockene-Augen-Syndrom, neue Technologien und Materialien zur Rückgewinnung von Lithium aus ausgedienten Batterien und Akkus oder der Einsatz von Tintenstrahldruckern für die Herstellung industrieller Perowskit-Silizium-Tandemsolarzellen zeigen einmal mehr die Vielfalt und Innovationskraft der Forschung am INM. Auch aus finanzieller Sicht war das Jahr erfolgreich. Die Drittmitteleinnahmen konnten weiterhinauf einem hohen Niveau gehalten werden. [...

A Comparative Study between Thiol-Ene and Acrylate Photocrosslinkable Hyaluronic Acid Hydrogel Inks for Digital Light Processing

Photocrosslinkable formulations based on the radical thiol-ene reaction are considered better alternatives than methacrylated counterparts for light-based fabrication processes. This study quantifies differences between thiol-ene and methacrylated crosslinked hydrogels in terms of precursors stability, the control of the crosslinking process, and the resolution of printed features particularized for hyaluronic acid (HA) inks at concentrations relevant for bioprinting. First, the synthesis of HA functionalized with norbornene, allyl ether, or methacrylate groups with the same molecular weight and comparable degrees of functionalization is presented. The thiol-ene hydrogel precursors show storage stability over 15 months, 3.8 times higher than the methacrylated derivative. Photorheology experiments demonstrate up to 4.7-times faster photocrosslinking. Network formation in photoinitiated thiol-ene HA crosslinking allows higher temporal control than in methacrylated HA, which shows long post-illumination hardening. Using digital light processing, 4% w/v HA hydrogels crosslinked with a dithiol allowed printing of 13.5 × 4 × 1 mm3 layers with holes of 100 µm resolution within 2 s. This is the smallest feature size demonstrated in DLP printing with HA-based thiol-ene hydrogels. The results are important to estimate the extent to which the synthetic effort of introducing –ene functions can pay off in the printing step

Agglomeration of gold nanoparticles in microgravity

The arrangement and distribution of nanoparticles inside a matrix crucially affect the material properties of nanocomposites. Agglomeration of the particles and the gravitational sedimentation of the agglomerates can alter the structure of the particles inside the matrix. To quantify the influence of gravity, agglomeration experiments were performed under normal and microgravity conditions. An experimental set up was successfully developed to study the temperature induced agglomeration of hexadecanethiol-capped gold nanoparticles in tetradecane with dynamic light scattering. The sample was heated inside an aluminum block and injected into the pre-cooled measurement cell. Microgravity experiments were realized in the drop tower of the ZARM Institute (Bremen, Germany), providing a microgravity duration of 9.3 s. Comparing those measurements with the corresponding ground experiments showed the formation of larger agglomerates in microgravity, indicating a more reaction limited agglomeration on ground and a more diffusion limited agglomeration in microgravity. In line with this assumption, a stronger dependency between the initial particle concentration and the size of the formed agglomerates was observed in microgravity. Increasing the gold concentration by a factor of 2.7 on ground doubled the hydrodynamic diameter. In microgravity, however, increasing the gold concentration by a factor of 3.8 led to an increase in the hydrodynamic diameter by a factor of 3.8.Die Anordnung und Verteilung von Nanopartikeln in einer Matrix hat wesentlichen Einfluss auf die Eigenschaften von Nanokompositen. Die Agglomeration der Partikel und Sedimentation der Agglomerate können die Anordnung der Partikel innerhalb der Matrix verändern. Um den Einfluss der Schwerkraft zu quantifizieren, wurden Agglomerationsversuche unter normalen - und Mikrogravitationsbedingungen durchgeführt. Ein Versuchsaufbau zur Verfolgung der temperaturinduzierten Agglomeration von Hexadecanthiol stabilisierten Goldnanopartikel in Tetradecan mit dynamischer Lichtstreuung wurde erfolgreich entwickelt. Die Probe wurde in einem Aluminiumblock erhitzt und in die vorgekühlte Messzelle injiziert. Mikrogravitationsexperimente wurden im Fallturm des ZARM-Instituts (Bremen, Deutschland) mit einer Mikrogravitationsdauer von 9,3 s durchgeführt. Der Vergleich der Messungen mit den Bodenexperimenten zeigte die Bildung größerer Agglomerate in Schwerelosigkeit, was auf eine eher reaktionslimitierte Agglomeration am Boden und eine eher diffusionslimitierte Agglomeration in Mikrogravitation hinweist. Damit übereinstimmend wurde eine stärkere Abhängigkeit zwischen der Partikelkonzentration und der Größe der gebildeten Agglomerate in Schwerelosigkeit gefunden. Am Boden führte die Erhöhung der Konzentration um den Faktor 2,7 zur Verdopplung des hydrodynamischen Durchmessers. In Mikrogravitation führte die Erhöhung der Konzentration um den Faktor 3,8 zur Erhöhung des Durchmessers um den Faktor 3,8

Morphology, performance, and stability of flexible and transparent electrodes imprinted from gold nanowires and -spheres

Flexible transparent electrodes (FTEs) were prepared from gold nanospheres and ultra-thin gold nanowires with oleylamine ligand shell and characterised. Their colloidal inks were patterned using direct nanoimprint lithography at different particle concentrations in cyclohexane on polyethylene terephthalate substrates with a patterned polydimethylsiloxane stamp. The wire inks agglomerated upon dilution, while sphere inks did not undergo this entropy-driven mechanism. At the highest printed concentration they were still well dispersed. Plasma sintering converted the imprinted grids into conductive electrodes, but only partially removed the ligands. The sintered lines consisted of a hybrid core and a thin conductive metal shell. Wire-based shells had a coarse surface microstructure and pronounced porosity. This rendered the wire-based FTEs instable. Spheres formed smooth shells with little or no porosity, enabling a beneficial ageing process. Immediately after plasma sintering, the ratio of optical transmittance to electrical resistance for wire-based FTEs exceeded that of sphere-based FTEs. Ageing reversed this order. The instability of wire-based FTEs was overcome by PEDOT:PSS coatings.Flexible transparente Elektroden (FTEs) wurden aus Goldnanokugeln und aus ultradünnen Goldnanodrähten mit Oleylamin-Ligandenhülle hergestellt und charakterisiert. Ihre kolloidalen Tinten wurden durch direkte Nanoprägelithographie bei verschiedenen Partikelkonzentrationen in Cyclohexan auf Polyethylenterephthalat-Substraten mit einem eine Prägestruktur aufweisenden Polydimethylsiloxan-Stempel strukturiert. Die drahtbasierten Tinten agglomerierten beim Verdünnen. Kugelbasierte Tinten unterlagen dem Entropie getriebenen Mechanismus nicht. Sie blieben auch bei der höchsten geprägten Konzentration dispers verteilt. Plasmasintern überführte die geprägten Gitter in leitfähige Elektroden, entfernte die Liganden dabei aber nur teilweise. Die gesinterten Linien bestanden aus einem hybriden Kern und einer dünnen leitenden Metallschale. Die Schalen auf Drahtbasis hatten eine grobe Oberflächenmikrostruktur und eine ausgeprägte Porosität. Dies machte die Draht-FTEs sehr instabil. Kugeln bildeten glatte Schalen mit wenig oder keiner Porosität. Sie sind die Basis für eine vorteilhafte Alterung. Direkt nach der Plasmabehandlung übertraf das Verhältnis von optischer Transmission zu elektrischem Widerstand bei Draht-FTEs jenes von Kugel-FTEs. Alterung kehrte diese Reihenfolge um. Die Instabilität der Draht-FTEs wurde durch eine PEDOT:PSS Beschichtung überwunden