Scientific publications

This article describes advancements in the ongoing digital transformation in materials science and engineering. It is driven by domain-specific successes and the development of specialized digital data spaces. There is an evident and increasing need for standardization across various subdomains to support science data exchange across entities. The MaterialDigital Initiative, funded by the German Federal Ministry of Education and Research, takes on a key role in this context, fostering collaborative efforts to establish a unified materials data space. The implementation of digital workflows and Semantic Web technologies, such as ontologies and knowledge graphs, facilitates the semantic integration of heterogeneous data and tools at multiple scales. Central to this effort is the prototyping of a knowledge graph that employs application ontologies tailored to specific data domains, thereby enhancing semantic interoperability. The collaborative approach of the Initiative's community provides significant support infrastructure for understanding and implementing standardized data structures, enhancing the efficiency of data-driven processes in materials development and discovery. Insights and methodologies developed via the MaterialDigital Initiative emphasize the transformative potential of ontology-based approaches in materials science, paving the way toward simplified integration into a unified, consolidated data space of high value.

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.

Antibiotic resistance in chronic lung infections caused by Pseudomonas aeruginosa requires alternative approaches to improve antibiotic efficacy. One promising approach is the use of adjuvant compounds that complement antibiotic therapy. This study explores the potential of menadione as an adjuvant to azithromycin against planktonic cells and biofilms of P. aeruginosa, focusing on its mechanisms of action and cytotoxicity in pulmonary cell models. Methods: The effect of menadione in improving the antibacterial and antibiofilm potency of azithromycin was tested against P. aeruginosa. Mechanistic studies in P. aeruginosa and AZMr-E. coli DH5α were performed to probe reactive oxygen species (ROS) production and bacterial membrane disruption. Cytotoxicity of antibacterial concentrations of menadione was assessed by measuring ROS levels and membrane integrity in Calu-3 and A549 lung epithelial cells. Results: Adding 0.5 µg/mL menadione to azithromycin reduced the minimum inhibitory concentration (MIC) by four-fold and the minimum biofilm eradication concentration (MBEC) by two-fold against P. aeruginosa. Adjuvant mechanisms of menadione involved ROS production and disruption of bacterial membranes. Cytotoxicity tests revealed that antibacterial concentrations of menadione (≤64 µg/mL) did not affect ROS levels or membrane integrity in lung cell lines. Conclusions: Menadione enhanced the efficacy of azithromycin against P. aeruginosa while exhibiting a favorable safety profile in lung epithelial cells at antibacterial concentrations. These findings suggest that menadione is a promising antibiotic adjuvant. However, as relevant data on the toxicity of menadione is sparse, further toxicity studies are required to ensure its safe use in complementing antibiotic therapy.

Hydrogels are natural/synthetic polymer-based materials with a large percentage of water content, usually above 80 %, and are suitable for many application fields such as wearable sensors, biomedicine, cosmetics, agriculture, etc. However, their performance is susceptible to environmental changes in temperature, relative humidity, and mechanical deformation due to their aqueous and soft nature. We investigate the mechanical response of both filled and unfilled alginate/gellan hydrogels using a combined axial-torsional rheometric approach with cylindrical samples of large length/diameter ratio under controlled temperature and relative humidity. Dynamic Mechanical Analysis (DMA) is performed on the same specimen in both torsion and extension under identical experimental conditions. This rheometric approach ensures consistent initial and boundary conditions, which are essential for a reliable estimation of viscoelastic moduli G* and E*, and their dependence on temperature, frequency, and relative humidity. Our findings indicate that humidity critically affects the mechanical response of the material due to sample volume shrinkage, necessitating corrections to the viscoelastic moduli. We also find temperature plays a role only at low/medium relative humidity values. The inclusion of fillers leads to a modest increase in the elasticity of the hydrogel, probably due to restricted water diffusion out of the sample. In connection with the latest, unfilled samples in breaking tests present only slippage due to twist-induced surface water excess, opposite to breakage events shown by filled samples, probably linked to restricted water diffusion.

As we turn the page to a new year, it is a fitting moment to reflect on 2024, a year marked by remarkable strides in sustainable energy research and innovation. Energy Advances has been privileged to serve as a platform for groundbreaking studies that aim to address critical global challenges in energy generation, storage, and sustainability. This editorial revisits some of the year’s highlights, celebrates key accomplishments, and looks ahead to the exciting prospects of 2025. In 2024, we were delighted to hold the Energy Advances Editorial Board meeting in person at our London office, Burlington House. The day was filled with exciting discussions about the success and future of the journal. We were also fortunate to have Editorial Board members Matthew Suss, Raymond Wong and Michael Naguib attending in person.

Materials containing imidazole have been used as promising substances in the fields of life sciences, environmental science, and electrochemistry. In this study, tailored core–shell particles that respond to acidic solutions and fluorine-containing hydrophobic anions were synthesized through starved-feed emulsion polymerization. Imidazole, which responds to proton acids and hydrophobic anions, was incorporated as a functional moiety into the shell of the particles. The soft and viscoelastic matrix was composed of the copolymer, poly((n-butyl acrylate)-co-(1-vinylimidazole)), allowing for control of the hydrodynamic diameter of the core–shell particles due to the balance between hydrophilic and hydrophobic properties. The size comparison of monodisperse particles in the colloid state was investigated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). Changes in the glass transition temperature, depending on the copolymer ratio, were calculated using the Fox equation. The particles were melt-sheared after extrusion to produce viscoelastic opal films, arranging the particles into colloidal crystal stacks showing vivid structural colors. The optical features changed in response to acidic solutions and hydrophobic anions and were examined using in situ ultraviolet–visible (UV–vis) spectroscopy. The degree of hydrophilicity of the film was compared through contact angle measurements. The manufactured smart opal film can be applied as an affordable sensor that exhibits optical color changes in response to acidic pH and hydrophobic anions.

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.

Living natural materials have remarkable sensing abilities that translate external cues into functional changes of the material. The reconstruction of such sensing materials in bottom-up synthetic biology provides the opportunity to develop synthetic materials with life-like sensing and adaptation ability. Key to such functions are material modules that translate specific input signals into a biomolecular response. Here, we engineer a synthetic organelle based on liquid–liquid phase separation that translates a metabolic signal into the regulation of gene transcription. To this aim, we engineer the pyruvate-dependent repressor PdhR to undergo liquid–liquid phase separation in vitro by fusion to intrinsically disordered regions. We demonstrate that the resulting coacervates bind DNA harboring PdhR-responsive operator sites in a pyruvate dose-dependent and reversible manner. We observed that the activity of transcription units on the DNA was strongly attenuated following recruitment to the coacervates. However, the addition of pyruvate resulted in a reversible and dose-dependent reconstitution of transcriptional activity. The coacervate-based synthetic organelles linking metabolic cues to transcriptional signals represent a materials approach to confer stimulus responsiveness to minimal bottom-up synthetic biological systems and open opportunities in materials for sensor applications.

Soft-adaptive electronics require both sensor and conductor materials. The key parameter for these materials is their mechanoelectrical properties. Liquid metals and solid conductive composites have been exploited in this application field, but both are limited by either their chemical stability or limited flexibility, respectively. Electrofluids are a novel approach toward soft electronic components. They are concentrated colloidal suspensions of conductive particles, in which dynamic contacts retain electrical conductivity under deformation, filling the gap between liquid metals and solid composites. Here, the mechanical and electrical network interplay of electrofluids is studied based on multi-walled carbon nanotubes (MWCNTs) in glycerol. These networks arise at different filler concentrations, showing a different response to external deformations. It is found that electrical conductivity occurs without the presence of a rigid mechanical network, which allows MWCNT suspensions to be electrically conductive even under flow conditions. By performing rheoelectrical measurements, the study observed how the mechanical and electrical networks evolve with the applied deformation. The study demonstrates the applicability of electrofluids with tailored mechanoelectrical properties as soft electrical connectors.

The benefit that antibiotics confer to the welfare of mankind is threatened by bacterial resistance. Resistance to daptomycin, a cyclic lipopeptide frequently used for the treatment of complicated bacteremia, is a prime example of this alarming situation. As the restricted number of antibacterial drug targets limits de novo development, chemical modification of existing compounds represents an alternative development option for future antimicrobials. This approach involves altering compounds to target bacteria through multiple mechanisms and/or to reinforce them against resistant strains. Herein, the conjugation of polycationic peptides to daptomycin enhances its effectiveness against a highly daptomycin-resistant laboratory strain of Staphylococcus aureus and clinical isolates of Enterococcus faecium with reduced daptomycin sensitivity. Notably, unlike daptomycin, the activity of these conjugates does not necessarily depend on the calcium concentration. In addition to regaining bacteriolytic activity, the findings indicate the acquisition of an additional or amended mode of action as evidenced by pore formation and the disruption of membrane potential. The combination of enhanced in vitro potency, in vivo activity, and tolerability highlights the potential of this drug modification strategy in combating multidrug-resistant bacteria.