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6 papers

Simultaneous learning of static and dynamic charges.

Stärk P et al. · Jul 8, 2026

Long-range interactions and electric response are essential for accurate modeling of condensed-phase systems, but capturing them efficiently remains a challenge for atomistic machine learning. Traditionally, these two phenomena can be represented by static charges that underlie Coulomb interactions between atoms, and dynamic charges such as atomic polar tensors-aka Born effective charges-describing the response to an external electric field. We critically compare different approaches to learn both types of charges within a single model architecture, taking bulk water and water clusters as paradigmatic examples: (1) learning them independently; (2) coupling static and dynamic charges based on their physical relationship with a single global coupling constant to account for dielectric screening; (3) coupled learning with a local, environment-dependent screening factor. In the coupled case, correcting for dielectric screening is essential, yet the common assumption of homogeneous, isotropic screening breaks down in heterogeneous systems such as water clusters. A learned, environment-dependent screening restores high accuracy for the dynamic charges. However, the accuracy gain over independent dynamic predictions is negligible, while the computational cost increases compared to using separate models for static and dynamic charges. This suggests that, despite the formal connection between the two charge types, modeling them independently is the more practical choice for both condensed-phase and isolated cluster systems.

Materials Science

Synthesis and pyroelectric response of disperse red 1 functionalized silicones: cyclic monomer, homopolymer, and block copolymer derivatives.

Beccard MS et al. · Jul 6, 2026

Pyroelectric materials enable the direct conversion of thermal fluctuations into electrical energy, offering a promising approach to waste heat recovery. While pyroelectric polymers are highly valued for their scalable synthesis, mechanical flexibility, and tunable properties, the field is currently dominated by poly(vinylidene fluoride) (PVDF)-based materials, which present environmental and processing challenges. To develop fluorine-free alternatives and elucidate the influence of molecular architecture on thermal-to-electrical conversion, we synthesized a series of siloxane-based materials functionalized with Disperse Red 1 (DR1) moieties, including a cyclic siloxane monomer, a homopolysiloxane, and a block copolysiloxane. Differential scanning calorimetry confirms the semicrystalline nature of these siloxanes, with glass transitions ( T g ) near room temperature and melting temperatures of about 80 °C. Notably, even unpoled samples exhibit a measurable pyroelectric response at elevated temperatures. The pyroelectric response at low temperatures is significantly enhanced by poling the crystalline domains in an electric field above the melting transitions ( T m ). Among the synthesized materials, the homopolymer exhibited the highest pyroelectric response (0.66 µC m -2 K -1 at 60 °C). While this value is significantly lower than the typical values for PVDF (>20 µC m -2 K -1 ), it should be noted that the processing and poling steps differ substantially. Under similar conditions, the PVDF value was only twice that of the homopolymer. Even more interesting, in an unpoled sample, the homopolymer shows a response similar to that of the poled sample, while PVDF shows almost no response. The superior response for the unpoled sample is attributed to the synergistic effects of DR1 self-ordering and secondary pyroelectricity-the strain-induced changes in dipole density resulting from thermal expansion. These findings provide a framework for designing high-performance, silicone-based pyroelectric transducers through precise structural control.

Materials Science

Radiolabeled Angiopep-2 Peptide Vector as a Preclinical Platform for Blood-Brain Barrier Targeting: Synthesis, Radiolabeling, and Preliminary In Vivo Biodistribution in Mice.

Fotou E et al. · Jul 1, 2026

Brain tumor therapy remains limited by the blood-brain barrier (BBB), which restricts drug access. BBB-penetrating peptides offer a promising strategy for delivering therapeutic and diagnostic payloads. Angiopep-2 is a well-established vector, yet novel radioconjugates based on this vector remain of interest. We report the synthesis and evaluation of DOTA-Angiopep-2 for radiolabeling with Lutetium-177 ( 177 Lu) and Terbium-161 ( 161 Tb). Notably, 177 Lu serves as a β- and γ-emitter, whereas 161 Tb is an Auger and β-emitter; both are utilized in therapy and SPECT imaging. Peptides were synthesized via solid-phase peptide synthesis. Cytotoxicity assays in T98 glioblastoma cells showed that Angiopep-2 is well-tolerated, maintaining ~100% viability at 20 μM and a moderate decline up to 100 μM. Radiolabeling achieved yields > 95% with excellent radiochemical stability at room temperature for up to 10 days and moderate stability in the presence of human serum. Biodistribution in healthy CFW mice showed a brain-associated radioactivity of 0.24% ± 0.05% IA/g at 5 min p.i. and a 12-fold increase in the brain-to-blood ratio (0.028-0.339) by 60 min p.i. These results support DOTA-Angiopep-2 as a versatile platform for radionuclide delivery and a potential candidate for future glioma-targeted studies. Further studies in tumor-bearing models are ongoing to evaluate therapeutic efficacy and translational potential.

Materials Science

Mycobacterium tuberculosis partitions the Krebs cycle under iron starvation.

Serafini A et al. · Jun 25, 2026

In this study, we investigated how iron limitation alters central metabolism in Mycobacterium tuberculosis using metabolomics and stable isotope tracing. Our findings reveal a well-orchestrated metabolic programme to enable Krebs cycle activity despite the inefficient action of its iron-dependent enzymes. Under such conditions, carbon flux through the oxidative branch of the Krebs cycle is stalled, resulting in the accumulation of metabolites that are partially secreted. As a result, carbon flux from glycolysis is partially diverted to the reductive branch of the Krebs cycle to support the production of oxaloacetate and malate through the activity of phosphoenolpyruvate carboxykinase and pyruvate carboxylase. Both branches terminate with the synthesis of malate, which is secreted. This unprecedented split of the Krebs cycle and malate secretion in a bacterial pathogen facilitates the continuous flow of carbon through the core of carbon metabolism, overcoming the metabolic stalling triggered by iron starvation.

Materials Science

Analysis of lipid-assisted self-assembly of hydrophobic CuInS2/ZnS quantum dots into water-stable nanoclusters that perform intra-cluster energy transfer.

Whipp JT et al. · Jun 25, 2026

Quantum dots (QDs) are nanocrystalline semiconductors that have the ability to perform efficient Förster resonance energy transfer (FRET) to biomolecules and other nanoparticles. Aqueous environments are required for applications related to biological systems, and common hydrophobic QDs will tend to cluster under these conditions. Whilst large (microscale) aggregates of QDs are undesirable, small (nanoscale) clusters could have applications as the active component in bio-imaging, bio-sensors or bio-photovoltaics. In this study, we developed a new procedure to utilize lipids to control the assembly of 'nanoclusters' of copper indium sulfide/zinc sulfide (CuInS 2 /ZnS) core/shell QDs. High-resolution electron microscopy revealed that the QDs had a particle size of ∼3.3 nm when they were in organic solvents and formed clusters of ∼40 nm when the nanoparticles were exchanged into aqueous solution in the presence of lipids. Particle sizing by nanoparticle tracking analysis suggested that the overall hydrodynamic size was 100-200 nm, which is consistent with an electron-dense core of clustered QDs surrounded by looser lipid assemblies or higher-order structures. The lipid was found to be essential for stabilizing the cluster, with fluorescence microscopy and spectroscopy confirming that the lipids and QDs were colocalized (using fluorescently-tagged lipids). Ensemble spectroscopy measurements revealed that there was a consistent red-shift of the emission peak, and a reduction in the excited state lifetime, for QD nanoclusters suspended in an aqueous buffer as compared to isolated QDs dissolved in organic solvents. The combined data provides strong evidence that downhill energy transfer occurs within one cluster from small, high-bandgap QDs to larger, low-bandgap QDs. Our findings contribute to a new understanding of how QD-QD and QD-lipid interactions influence their photophysical properties. Our work provides a new protocol based on a physical self-assembly that is modular and adaptable: alternative lipids or QDs and different buffer conditions (salt, pH) could be used. Future work could incorporate membrane proteins in the development of QD-biohybrid systems towards new applications in bio-nanotechnology.

Materials Science

Synergistic Regulation of Postharvest Physiology and Biochemical Quality of Peach (Prunus persica L.) Through Salicylic Acid and Plant-Based Edible Treatments.

Shajari S et al. · Jun 25, 2026

Postharvest deterioration represents a major challenge in maintaining the market quality of peach fruit, and the application of environmentally benign treatments such as edible coatings has gained increasing attention as an effective strategy to extend storage life. Accordingly, the present study evaluated the effects of several natural coating materials on the postharvest quality of peach ( Prunus persica L.). The experimental treatments consisted of salicylic acid at three concentrations (0, 1, and 2 mM), Aloe vera gel at 0%, 20%, and 30%, and clove extract at 0, 150, and 300 ppm. Overall, the application of edible coatings significantly enhanced fruit storability and quality attributes compared with untreated control fruit. Among the treatments, fruit treated with 2 mM salicylic acid and 300 ppm clove extract exhibited the highest fruit weight (89.66 g). Whereas the fruits without salicylic acid application showed the greatest fruit weight loss (15.55%) and the highest vitamin C (32.02 mg 100 g -1 FW) was obtained at 2 mM salicylic acid treatment. In terms of clove extract treatments, fruit coated with 300 ppm clove extract maintained the greatest fruit texture firmness (3.69 kg cm -2 ), total phenolic content (219.88 mg GAE 100 g -1 FW), vitamin C (mg 100 g -1 FW), and total antioxidant capacity (446.94 μmol TE g -1 FW), whereas no application treatment recorded the highest fruit weight loss (14.72%) and total acidity (4.16 g malic acid 100 g -1 FW). In conclusion, the findings demonstrate that natural edible coatings, particularly when applied in combination, are effective in reducing oxidative stress, suppressing enzymatic browning, and improving postharvest quality, thereby representing a promising and sustainable approach for extending the shelf life of peach fruit. These findings suggest that activation of antioxidant system likely stimulated by salicylic acid and supplemented by aloe vera or clove extract was a central mechanism underlying quality preservation.

Materials Science