Frontiers in Soft Matter最新文献

{"title":"Structure and Pattern Formation in Biological Liquid Crystals: Insights From Theory and Simulation of Self-Assembly and Self-Organization","authors":"Ziheng Wang, P. Servio, A. Rey","doi":"10.3389/frsfm.2022.904069","DOIUrl":"https://doi.org/10.3389/frsfm.2022.904069","url":null,"abstract":"This review presents theory and simulation of liquid crystal phase ordering in biological fibrous materials, solutions, and composites in the presence of elastic fields, second phase inclusions, and transport phenomena, including complex shear-extensional flow and mass transfer. Liquid crystal self-assembly through phase ordering on elastic deformable membranes is first applied to characterize the mechanisms that control the structures in plant cell walls, highlighting how curvophobic and curvophilic effects introduce new structuring fields beyond hard-core repulsion. Then chiral nematic self-assembly is simulated in a mesophase containing fibrillar colloidal inclusions (liquid crystal-fibre composites) to demonstrate how the inclusion positional order generates defects and disclinations as shown in the plant cell wall. Coupling phase ordering to tuned transport phenomena is shown how and why it leads to self-organization such as paranematic states of dilute acidic aqueous collagen solutions. Further directed dehydration of well-organized paranematic collagen leads to defect free cholesteric films only when directed dehydration is synchronized with chirality formation. In addition, the ubiquitous surface nanowrinkling of cholesterics is captured with surface anchoring. In these four representative systems, the new mechanisms that enhance the well-known exclude volume interactions are identified quantified and validated with experimental data. Future directions to create new advanced multifunctional materials based on principles of self-assembly and self-organization are identified by leveraging the new couplings between material structure, geometry, and transport phenomena.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132964183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oscillatory Structural Forces Across Dispersions of Micelles With Variable Surface Charge","authors":"M. Ludwig, Philipp Ritzert, Ramsia Geisler, S. Prévost, R. von Klitzing","doi":"10.3389/frsfm.2022.890415","DOIUrl":"https://doi.org/10.3389/frsfm.2022.890415","url":null,"abstract":"When two surfaces interact across colloidal dispersions, oscillatory structural forces often arise due to an ordering of colloidal particles. Although this type of forces was intensively studied, the effect of the surface charge of the colloidal particles is still poorly understood. In the present study, the surface charge of colloidal particles is varied by changing the ratio of nonionic (Tween20) and anionic (sodium dodecyl sulfate, SDS) surfactants of micellar dispersions. The same micellar systems were previously characterised with small-angle neutron scattering (SANS) by the authors, revealing that mixed nonionic-anionic surfactant micelles with variable surface charge form. The present paper addresses the ordering phenomena of the micellar systems under confinement. Therefore, forces across these dispersions were measured for varying surface charges and volume fractions of the micelles, using colloidal-probe atomic force microscopy (CP-AFM). The combination of SANS and CP-AFM experiments allows the dispersions structure in bulk and under geometrical confinement to be compared in terms of the characteristic interparticle distance, correlation length, and ordering strength: In bulk and under confinement, the characteristic intermicellar distance increases by introducing surface charges to micelles until the electrostatic repulsion forces the micelles into a specific ordering. There, the characteristic intermicellar distance purely relates to the micelle volume fraction ϕ as ∝ ϕ −1/3. While in dispersions of uncharged micelles the characteristic intermicellar distance is reduced from bulk to confinement, no such compressibility is observed once the micelles are charged. Furthermore, variation of the micelles surface charge has only little effect on the correlation length of the micelles ordering which is mainly governed by hard-sphere interactions, especially in concentrated dispersions. Introducing surface charges, however, enhances the ordering strength (i.e., the amplitude) of oscillatory structural forces due to stronger electrostatic repulsions of the micelles with the equally charged confining surface. This surface-induced effect is not represented in bulk scattering experiments. GRAPHICAL ABSTRACT","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123569629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Average evolution and size-topology relations for coarsening 2d dry foams","authors":"A. Chieco, J. Sethna, D. Durian","doi":"10.3389/frsfm.2022.941811","DOIUrl":"https://doi.org/10.3389/frsfm.2022.941811","url":null,"abstract":"Two-dimensional dry foams coarsen according to the von Neumann law as dA/dt ∝ (n − 6) where n is the number of sides of a bubble with area A. Such foams reach a self-similar scaling state where area and side-number distributions are stationary. Combining self-similarity with the von Neumann law, we derive time derivatives of moments of the bubble area distribution and a relation connecting area moments with averages of the side-number distribution that are weighted by powers of bubble area. To test these predictions, we collect and analyze high precision image data for a large number of bubbles squashed between parallel acrylic plates and allowed to coarsen into the self-similar scaling state. We find good agreement for moments ranging from 2–20.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132363406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Label-Free Detection of Ochratoxin A Using Aptamer as Recognition Probe at Liquid Crystal-Aqueous Interface","authors":"M. Devi, Kavyasree A, I. Pani, Soma Sil, S. Pal","doi":"10.3389/frsfm.2022.835057","DOIUrl":"https://doi.org/10.3389/frsfm.2022.835057","url":null,"abstract":"Aqueous interfaces of stimuli-responsive, thermotropic nematic liquid crystals (LC) have been utilized in the design of biosensing platforms for a range of analytes. Owing to the orientational changes in LC, these interfaces can easily report aptamer-target binding events at the LC-aqueous interface. We demonstrate a label-free, simple and robust technique for the detection of Ochratoxin A (OTA) using aptamer as the recognition probe. The self-assembly of CTAB (cetyltrimethylammonium bromide; cationic surfactant) at aqueous-LC interface gives a homeotropic orientation of LC. In presence of negatively charged OTA specific aptamer, aptamer forms a complex with CTAB. Formation of aptamer-CTAB complex results in ordering transition of LCs to planar/tilted. In presence of OTA, OTA forms a strong and stable G-quadruplex structure of aptamer that results in the redistribution of CTAB at LC-aqueous interface and leads to homeotropic orientation of LC. The designed LC aptasensor exhibits a detection limit of 0.1 nM. We observed that the sensitivity of LC aptasensor was affected by the pH and ionic strength. In addition, we demonstrated the applicability of the designed LC aptasensor for the detection of OTA in tap water and apple juice. This approach offers advantages over the conventional detection methods in terms of fabrication, ease of operation, and analysis.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115253300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparing α-Synuclein Fibrils Formed in the Absence and Presence of a Model Lipid Membrane: A Small and Wide-Angle X-Ray Scattering Study","authors":"Marija Dubackic, S. Linse, E. Sparr, U. Olsson","doi":"10.3389/frsfm.2021.741996","DOIUrl":"https://doi.org/10.3389/frsfm.2021.741996","url":null,"abstract":"Amyloid fibrils are associated with a number of different neurodegenerative diseases. Detailed knowledge of the fibril structure will be of importance in the search of therapy and may guide experiments to understand amyloid formation. In this paper we investigate the morphology of α-synuclein amyloid fibrils, associated with Parkinson’s disease, formed under different conditions. In particular, we study, by means of small and wide-angle X-ray scattering, whether the presence of model lipid membranes affect the overall structure of the fibrils formed, motivated by the fact that amyloid fibrils in vivo are formed in a highly lipid-rich environment. Comparing fibrils formed in the presence of lipid with fibrils formed in their absence, show that the presence of lipids has no detectable effect on the fibril cross-section radius and that the characteristic β-strand repeat distance of 4.7 Å of the extended intermolecular β-sheets remains unaffected. We also show that the observed fibril radius is consistent with a fibril structure composed of two protofilaments. This indicates overall that the particular fibril structure, with their stacks of two-dimensionally folded α-synuclein molecules, represent a deep free energy minimum, not largely affected by the co-aggregation with lipids.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125695528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Grand Challenges in Soft Matter","authors":"R. Mezzenga","doi":"10.3389/frsfm.2021.811842","DOIUrl":"https://doi.org/10.3389/frsfm.2021.811842","url":null,"abstract":"From the food we cook in the kitchen, to the living cells which form our bodies, Soft Matter is ubiquitous in our every-day lives. How well do we understand Soft Matter and what do we miss to improve our comprehension of this fascinating class of matter? What are the challenges we face to translate fundamental understanding into impactful applications? This short personal perspective tackles some of the challenges associated with Soft Matter and provides possible directions forwards in addressing these challenges. From a chemistry perspective, the field of Soft Matter is just about a century-old, as one could very well consider the 1920 seminal paper of Staudinger “Über Polymerisation,” (Staudinger, 1920) as the spark which set the fire to the explosion of polymer chemistry, one of the core pillars of Soft Matter today. Since then, polymer chemistry has continuously reshaped the landscape of polymers. Polymers are easy to produce and can be cast or moulded into any possible shape; polymer synthesis can be engineered by catalysts to have very low-energy requirements and deliver polymers with high control precision in their molecular architecture. It is for these reasons (and much more) that today “plastics” has become one of the most widely spread man-made materials around the globe, but it is also via advanced polymer chemistry approaches that we are today actively seeking valid solutions for switching from petroleum-based plastics to biodegradable polymers (Tian et al., 2012), to enter into a more sustainable era of polymers, in full harmony with the environment and reducing their global impact on our society. From a physics perspective, the field of Soft Matter as a distinct scientific discipline effectively started only 15 years earlier, with the 1905 annus mirabilis seminal paper of Albert Einstein on Brownian motion (Einstein, 1905). This paper introduces a few ground-breaking concepts over which Soft Matter is still centred today, such as for example the linear t dependence of the mean square displacement of colloidal particles, or the derivation of the expression for the diffusion coefficient of a colloidal particle, an equation to which we today refer by as the Stokes-Einstein law. But perhaps one sentence is particularly revealing in that paper by Einstein: “. . .and is not apparent why a number of suspended particles should not produce the same osmotic pressure as the same number of molecules” (Einstein et al., 1956). The underlying assumption behind this sentence is that, by being the particles “suspended” they must possess an energy of the order of KbT: if not they would either sediment to the bottom or float to the surface of the fluid on which they are suspended. One could actually start from this very same sentence to provide an accurate definition of a colloidal particle, by defining it as any entity with a kinetic energy of the order of KbT, or whose trajectory follows a random walk, for which its mean square displacement acquire","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130931823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}