Bence Fehér

High‐aspect‐ratio polymeric micelles (filomicelles, FMs) are attractive anisotropic nanoparticles for a wide range of applications, however, their formation is typically confined to narrow hydrophilic/hydrophobic polymer block ratios, limiting systematic structure–property investigations. Consequently, independent control over micelle width, length, and stiffness remains challenging. A supramolecular polymerization‐induced self‐assembly (PISA) strategy using a bis‐urea core template was recently shown to robustly yield wormlike micelles across a wide range of core block lengths; however, the resulting FM lengths remained highly polydisperse. Herein, we investigate two strategies to tune the contour length: ( i ) Blending in polymer without the bis‐urea sticker and ( ii ) post‐micellization sonication. Unexpectedly, incorporating non‐sticker polymer can increase the contour length. Transmission electron microscopy (TEM), fluorescence cross‐correlation spectroscopy (FCCS), and high‐resolution atomic force microscopy (AFM) were used to elucidate the key factors contributing to this peculiar self‐assembly mechanism. Sonication‐induced cleavage led to shortening of the particles and narrower polydispersity in length. Combined, the two strategies provide access to a wide range of anisotropic micelles with accessible aspect ratios ranging from 1 to >150. Considering their long‐term (colloidal) stability, the presented system is an ideal model to study the effect of micellar anisotropy, for example, in drug delivery relevant scenarios.

A recently introduced one-pot strategy for polyelectrolyte self-assembly in aqueous solution, namely polymerization-induced electrostatic self-assembly (PIESA), enables in-situ polymerization and complexation of a polyelectrolyte block of a double hydrophilic block copolymer with an oppositely charged polymeric template. Unlike the conventional preparation of complex coacervate core micelles (C3Ms) by direct mixing of aqueous solutions of premade oppositely-charged polyelectrolytes, PIESA intrinsically couples polymerization and electrostatically-driven self-assembly within a single process. This coupling facilitates formation and equilibration of nanometer-sized C3M-like nanostructures. PIESA offers promising control over nanostructure formation, but the mechanistic pathways underlying structure formation and evolution in such systems remain poorly understood. To fill this knowledge gap, the structural evolution of nanoscale assemblies was tracked via time-variable small-angle X-ray scattering (SAXS) and light scattering measurements on quenched aliquots taken at different time points during a PIESA process. A detailed analysis of the SAXS profiles on an absolute intensity scale with molecular constraints, in conjunction with monomer conversions determined by 1H-NMR, reveals proceeding of nanostructure evolution in PIESA through three distinct stages: (I) Complexation and Particle Nucleation: a non-particulate regime marking the onset of nucleation, (II) Maturation and Growth: a particulate regime wherein particles grow via a diffusion-driven ripening mechanism, and (III) Polymerization Termination and Structural Stabilization: a particulate regime wherein particle coarsening and structural maturation cease. These findings provide fundamental insights into coupled polymerization and assembly kinetics in PIESA systems, offering a mechanistic framework that can guide the rational design and equilibration of next-generation polyelectrolyte nanostructures with tunable size and functionality.

Bacteriophages are gaining interest due to their potential use against multidrug‐resistant bacteria. Here, we investigated the structural dynamics of T7 bacteriophage tail fibers. The T7 virion comprises an icosahedral protein shell and a tail‐fiber complex, which is involved in bacterial target recognition and viral DNA injection. The virus has six L‐shaped, ∼40‐nm‐long fibers connected to the tail‐tube, which are thought to be essential for initial host recognition and, possibly, for surface exploration. By using high‐speed atomic force microscopy (HS‐AFM) and molecular dynamics (MD) simulations combined with small angle X‐ray scattering (SAXS), we analyzed the molecular structure and movements of isolated tail fibers and tail‐fiber complexes. We found that the kink region separating the proximal and distal sections of the fiber acts as a molecular hinge, which allows large‐scale dynamic bending. Furthermore, partial unwinding‐rewinding in the triple‐helical coiled‐coil structure of the proximal section permits gross fiber rotation and twisting. The two dynamic regions allow for large‐scale, rapid fiber flexing and extension, thus enabling an efficient topological search for anchorage sites by the phage on the host surface. Since the fiber‐assisted topological search is likely a universal mechanism of host recognition, modulating it could be used for fine‐tuning the phage‐bacterium infection process.

In oxygenic photosynthetic organisms, the light reactions are performed by protein complexes embedded in the lipid bilayer of thylakoid membranes (TMs). The organization of the bulk lipid molecules into bilayer structures provide optimal conditions for the build-up of the proton motive force (pmf) and its utilization for ATP synthesis. However, the lipid composition of TMs is dominated by the non-bilayer lipid species monogalactosyl diacylglycerol (MGDG), and functional plant TMs, besides the bilayer, contain large amounts of non-bilayer lipid phases. Bulk lipids have been shown to be associated with lumenal, stromal-side and marginal-region proteins and proposed to play roles in the self-assembly and photoprotection of the photosynthetic machinery. Furthermore, it has recently been pointed out that the generation and utilization of pmf for ATP synthesis according to the ‘protet’ or protonic charge transfer model Kell (Biochim Biophys Acta Bioenerg 1865(4):149504, 2024), requires high MGDG content Garab (Physiol Plant 177(2):e70230, 2025). In this study, to gain better insight into the structural and functional roles of MGDG, we employed all atom and coarse-grained molecular dynamics simulations to explore how temperature, hydration levels and varying MGDG concentrations affect the structural and dynamic properties of bilayer membranes constituted of plant thylakoid lipids. Our findings reveal that MGDG promotes increased membrane fluidity and dynamic fluctuations in membrane thickness. MGDG-rich stacked bilayers spontaneously formed inverted hexagonal phases; these transitions were enhanced at low hydration levels and at elevated but physiologically relevant temperatures. It can thus be inferred that MGDG plays important roles in heat and drought stress mechanisms.

Small-angle X-ray and neutron scattering (SAXS and SANS) are versatile techniques for studying the structure of various materials and particles, enabling investigations of structures from a few to hundreds of nanometres. However, interpreting SAXS or SANS data can be challenging, hence the need for effective training. Here, we present the website SAStutorials.org, which offers tutorials on small-angle scattering (SAS) data analysis. The website serves as a learning platform that supports active learning both in the classroom and through self-study. The tutorials cover basic concepts, advanced modelling and theoretical aspects of SAS. Each tutorial follows a structure based on the principle of SOLO taxonomy, guiding learners from minimal or no knowledge in a given area to the ability to tackle real-world problems. SAStutorials.org has been developed as a community tool, providing tutorials that encompass a broad range of data analysis types, leveraging various programs and investigating different materials. Moreover, the website and all its data are open source, encouraging contributions from the community.

Photosynthetica covers wide range of photosynthesis research or research including photosynthetic parameters of both experimental and theoretical nature.

Water‐soluble supramolecular polymers show great potential to develop dynamic biomaterials with tailored properties. Here, we elucidate the morphology, stability and dynamicity of supramolecular polymers derived from bisurea‐based monomers. An accessible synthetic approach from 2,4‐toluene diisocyanate (TDI) as the starting material is developed. TDI has two isocyanates that differ in intrinsic reactivity, which allows to obtain functional, desymmetrized monomers in a one‐step procedure. We explore how the hydrophobic/hydrophilic ratio affects the properties of the formed supramolecular polymers by increasing the number of methylene units from 10 to 12 keeping the hydrophilic hexa(ethylene glycol) constant. All bisurea‐based monomers form long, fibrous structures with 3–5 monomers in the cross‐section in water, indicating a proper hydrophobic\hydrophilic balance. The stability of the supramolecular polymers increases with an increasing amount of methylene units, whereas the dynamic nature of the monomers decreases. The introduction of one Cy3 dye affords modified supramolecular monomers, which co‐assemble with the unmodified monomers into fibrous structures. All systems show excellent water‐compatibility and no toxicity for different cell‐lines. Importantly, in cell culture media, the fibrous structures remain present, highlighting the stability of these supramolecular polymers in physiological conditions. The results obtained here motivate further investigation of these bisurea‐based building blocks as dynamic biomaterial.

The interfacial structure and morphology of films spread from hyperbranched polyethylene imine/sodium dodecyl sulfate (PEI/SDS) aggregates at the air/water interface have been resolved for the first time with respect to polyelectrolyte charged density. A recently developed method to form efficient films from the dissociation of aggregates using a minimal quantity of materials is exploited as a step forward in enhancing understanding of the film properties with a view to their future use in technological applications. Interfacial techniques that resolve different time and length scales, namely, ellipsometry, Brewster angle microscopy, and neutron reflectometry, are used. Extended structures of both components are formed under a monolayer of the surfactant with bound polyelectrolytes upon film compression on subphases adjusted to pH 4 or 10, corresponding to high and low charge density of the polyelectrolyte, respectively. A rigid film is related to compact conformation of the PEI in the interfacial structure at pH 4, while it is observed that aggregates remain embedded in mobile films at pH 10. The ability to compact surfactants in the monolayer to the same extent as its maximum coverage in the absence of polyelectrolyte is distinct from the behavior observed for spread films involving linear polyelectrolytes, and intriguingly evidence points to the formation of extended structures over the full range of surface pressures. We conclude that the molecular architecture and charge density can be important parameters in controlling the structures and properties of spread polyelectrolyte/surfactant films, which holds relevance to a range of applications, such as those where PEI is used, including CO₂ capture, electronic devices, and gene transfection.