Viviane Lütz Bueno

Last Name

Lütz Bueno

First Name

Viviane

ORCID

0000-0001-9735-5470

Organisational unit

01630 - Lehre HEST

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Publications1 - 10 of 24

From amyloid fibrils to microfiber condensates: Tuning microfluidic coextrusion of food-grade β-lactoglobulin-pectin core-shell fibers by changes of protein structure
Kutzli, Ines; Lütz Bueno, Viviane; Bagnani, Massimo; et al. (2023)
Food Hydrocolloids
Protein-based microfibers have potential applications in bioengineering and food but preserving and utilizing the unique nanomechanical properties of their protein building blocks at the micrometer scale remains a challenge. This study investigates the bottom-up fabrication of core-shell fibers by coaxial microfluidic spinning of pectin and β-lactoglobulin in different conformational states (monomeric, amyloid fibrils, shortened amyloid fibrils in their isotropic/nematic phases), gelled in CaCl2 solution. Fiber diameters ranged between 478 and 855 μm (wet state) and 107–135 μm (dry state). They showed clear core-shell cross-sections, except pectin-β-lactoglobulin monomer fibers where the compact protein is presumably understood to diffuse through the pectin matrix. The molecular orientation of the fiber building blocks was expressed as order parameters representing the alignment of pectin chains and amyloid fibrils parallel to the fiber axis calculated from synchrotron wide-angle X-ray scattering (WAXS) with a spatial resolution of 20 μm. Introduction of amyloid fibrils as the protein core increased the Young's modulus from 3.3 to 6.4 GPa and tensile strength from 117 to 182 MPa compared to pure pectin fibers. Increasing the protein core flow rate from 1 to 2 mL/h, however, caused helical bending of the core jet, a decrease in order, and ultimately worsened mechanical performance. Overall, full length amyloid fibrils proved to be more beneficial to the mechanical properties than shortened amyloid fibrils. By providing insight into the relationship between protein conformation, spinning flow rate, and resulting mechanical properties of core-shell microfibers, these results may contribute to the field of novel fibrous protein-based materials.
Amyloid-polysaccharide interfacial coacervates as therapeutic materials
Peydayesh, Mohammad; Kistler, Sabrina; Zhou, Jiangtao; et al. (2023)
Nature Communications
Coacervation via liquid-liquid phase separation provides an excellent opportunity to address the challenges of designing nanostructured biomaterials with multiple functionalities. Protein-polysaccharide coacervates, in particular, offer an appealing strategy to target biomaterial scaffolds, but these systems suffer from the low mechanical and chemical stabilities of protein-based condensates. Here we overcome these limitations by transforming native proteins into amyloid fibrils and demonstrate that the coacervation of cationic protein amyloids and anionic linear polysaccharides results in the interfacial self-assembly of biomaterials with precise control of their structure and properties. The coacervates present a highly ordered asymmetric architecture with amyloid fibrils on one side and the polysaccharide on the other. We demonstrate the excellent performance of these coacervates for gastric ulcer protection by validating via an in vivo assay their therapeutic effect as engineered microparticles. These results point at amyloid-polysaccharides coacervates as an original and effective biomaterial for multiple uses in internal medicine.
Hierarchical Structure of Cellulose Nanofibril-Based Foams Explored by Multimodal X-ray Scattering
Lütz Bueno, Viviane; Diaz, Ana; Wu, Tingting; et al. (2022)
Biomacromolecules
Structural characterization techniques are fundamental to correlate the material macro-, nano-, and molecular-scale structures to their macroscopic properties and to engineer hierarchical materials. Here, we combine X-ray transmission with scanning small-and wide-angle X-ray scattering (sSWAXS) to investigate ultraporous and lightweight biopolymer-based foams using cellulose nanofibrils (CNFs) as building blocks. The power of multimodal sSWAXS for multiscale structural characterization of self-assembled CNFs is demonstrated by spatially resolved maps at the macroscale (foam density and porosity), at the nanoscale (foam structural compactness, CNF orientation in the foam walls, and CNF packing state), and at the molecular scale (cellulose crystallite dimensions). Specifically, we compare the impact of freeze-thawing-drying (FTD) fabrication steps, such as static/stirred freezing and thawing in ethanol/water, on foam structural hierarchy spanning from the molecular to the millimeter scale. As such, we demonstrate the potential of X-ray scattering imaging for hierarchical characterization of biopolymers.
Photonics of Hydrothermally Treated β-Lactoglobulin Amyloids
Hanczyc, Piotr; Alfarano, Serena Rosa; Bolisetty, Sreenath; et al. (2024)
Small Science
Increased temperature and high pressure are applied to beta-lactoglobulin fibrils in the autoclave, resulting in the acquisition of a composite material comprised of partially disassembled amyloid fibrils and carbon dots. Confirmation of the preservation of the beta-sheet motif attributed to amyloids in the hydrothermally treated fibrils is obtained through wide-angle X-ray scattering and ThT assay. Z-scan analysis reveals a two-photon absorption (2PA) enhancement in the low-lying transition band (Lₐ) of tyrosine, while quantum chemical calculations demonstrate a correlation between the yield of 2PA and the interspace distance between aromatic residues. Overall, the intrinsic optical properties of amyloid fibrils treated in a subcritical water environment are found to be linked with the π-conjugation of tyrosine units and their through-space coupling. The resulting composite material is employed as a coating for a commercial ultraviolet light-emitting diode lamp, showcasing the potential utility of sustainable biomaterials with improved optical properties for photonics applications.
From nano to bite: Dietary fibers induce fracture mechanisms during high moisture extrusion of plant-based meat alternatives
Guan, Tong; Lutz-Bueno, Viviane; Schlangen, Miek; et al. (2026)
Food Hydrocolloids
High moisture extrusion (HME) is a key technology to produce meat alternatives with a fibrous texture. The incorporation of dietary fibers in plant-based formulations used for extrusion has shown to enhance the fibrous texture, yet the underlying mechanisms in the extrusion process remain elusive. Here we unravel the dietary fibers induced structuring mechanisms in extrusion from the nanoscale to the macroscale by combining small-angle neutron scattering, scanning small- and wide-angle X-ray scattering-based imaging, and automated image analysis (Fiberlyzer). The incorporation of pea fiber does not change the nanostructure but leads to the formation of cellulose-rich regions at the microscale, which acts as nucleation sites to initiate fractures in extrudates, resulting in a greater prevalence of fibrous structures at the macroscale. The incorporation of a mixture with high pectin-to-cellulose ratio alters nanostructures and reduces mechanical strength, while nanostructures and the mechanical strength can be preserved when incorporating a mixture with low pectin-to-cellulose ratio. Our study examines the dietary fibers induced structuring mechanisms in extrusion across multiple length scales, providing valuable insights for optimizing formulations in plant-based alternatives.
Hierarchical self-assembly of a reflectin-derived peptide
Dias, Ana Margarida Gonçalves Carvalho; Moreira, Inês Pimentel; Lychko, Iana; et al. (2023)
Frontiers in Chemistry
Reflectins are a family of intrinsically disordered proteins involved in cephalopod camouflage, making them an interesting source for bioinspired optical materials. Understanding reflectin assembly into higher-order structures by standard biophysical methods enables the rational design of new materials, but it is difficult due to their low solubility. To address this challenge, we aim to understand the molecular self-assembly mechanism of reflectin’s basic unit—the protopeptide sequence YMDMSGYQ—as a means to understand reflectin’s assembly phenomena. Protopeptide self-assembly was triggered by different environmental cues, yielding supramolecular hydrogels, and characterized by experimental and theoretical methods. Protopeptide films were also prepared to assess optical properties. Our results support the hypothesis for the protopeptide aggregation model at an atomistic level, led by hydrophilic and hydrophobic interactions mediated by tyrosine residues. Protopeptide-derived films were optically active, presenting diffuse reflectance in the visible region of the light spectrum. Hence, these results contribute to a better understanding of the protopeptide structural assembly, crucial for the design of peptide- and reflectin-based functional materials.
Polymer induced liquid crystal phase behavior of cellulose nanocrystal dispersions
Sun, Qiyao; Lütz Bueno, Viviane; Zhou, Jiangtao; et al. (2022)
Nanoscale Advances
Cellulose nanocrystals (CNCs) are a promising bio-based material that has attracted significant attention in the fabrication of functional hybrid materials. The rod-like shape and negative surface charge of CNCs enable their rich colloidal behavior, such as a liquid crystalline phase and hydrogel formation that can be mediated by different additives. This study investigates the effect of depletion-induced attraction in the presence of non-absorbing polyethylene glycol (PEG) of different molecular weights in CNC aqueous dispersions, where the polymer molecules deplete the space around particles, apply osmotic pressure and drive the phase transition. Polarized light microscopy (PLM), rheology, small angle X-ray scattering (SAXS) and atomic force microscopy (AFM) are used to characterize the phase behavior over a time period of one month. In our results, pure CNC dispersion shows three typical liquid crystal shear rheology regimes and cholesteric self-assembly behavior. Tactoid nucleation, growth and coalescence are observed microscopically, and eventually the dispersion presents macroscopic phase separation. PEG with lower molecular weight induces weak attractive depletion forces. Tactoid growth is limited, and the whole system turns into a fully nematic phase macroscopically. With PEG of higher molecular weight, attractive depletion force becomes predominant, thus CNC self-assembly is inhibited and nematic hydrogel formation is triggered. Overall, we demonstrate that depletion induced attraction forces by the addition of PEG enable precise tuning of CNC self-assembly and phase behavior with controllable mechanical strength and optical activity. These findings deepen our fundamental understanding of cellulose nanocrystals and advance their application in colloidal systems and nanomaterials.
Mechanical tuning of virus-like particles
Radiom, Milad; Keys, Timothy Gerard; Turgay, Yagmur; et al. (2023)
Journal of Colloid and Interface Science
Hypothesis: Virus-like particles (VLPs) are promising scaffolds for developing mucosal vaccines. For their optimal performance, in addition to design parameters from an immunological perspective, biophysical properties may need to be considered. Experiments: We investigated the mechanical properties of VLPs scaffolded on the coat protein of Acinetobacter phage AP205 using atomic force microscopy and small angle X-ray scattering. Findings: Investigations showed that AP205 VLP is a tough nanoshell of stiffness 93 ± 23 pN/nm and elastic modulus 0.11 GPa. However, its mechanical properties are modulated by attaching muco-inert polyethylene glycol to 46 ± 10 pN/nm and 0.05 GPa. Addition of antigenic peptides derived from SARS-CoV2 spike protein by genetic fusion increased the stiffness to 146 ± 54 pN/nm although the elastic modulus remained unchanged. These results, which are interpreted in terms of shell thickness and coat protein net charge variations, demonstrate that surface conjugation can induce appreciable changes in the biophysical properties of VLP-scaffolded vaccines.
Polymer Induced Liquid Crystal Phase Behavior of Cellulose Nanocrystal (CNC)
Sun, Qiyao; Lütz Bueno, Viviane; Zhou, Jiangtao; et al. (2022)
Book of Abstracts of the Annual European Rheology Conference (AERC 2022) and the VIII Iberian Meeting on Rheology (IBEREO 2022)
Oat Plant Amyloids for Sustainable Functional Materials
Zhou, Jiangtao; Li, Ting; Peydayesh, Mohammad; et al. (2022)
Advanced Science
Amyloid functional materials from amyloid fibril building blocks, produced in vitro from amyloidogenic natural proteins or synthetic peptides, show diverse functionalities ranging from environmental science and biomedicine, to nanotechnology and biomaterials. However, sustainable and affordable sources of amyloidogenic proteins remain the bottleneck for large-scale applications, and to date, interest remains essentially limited to fundamental studies. Plant-derived proteins would be an ideal source due to their natural abundance and low environmental impact. Hereby oat globulin, the primary protein of oat plant (Avena sativa), is utilized to yield high-quality amyloid fibrils and functional materials based thereof. These fibrils show a rich multistranded ribbon-like polymorphism and a fibrillization process with both irreversible and reversible pathways. The authors furthermore fabricate oat-amyloid aerogels, films, and membranes for possible use in water purification, sensors, and patterned electrodes. The sustainability footprint of oat-amyloids against other protein sources is demonstrated, anticipating an environmentally-efficient platform for advanced materials and technologies.

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Viviane Lütz Bueno

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