Soft Matter最新文献

{"title":"Coarsening dynamics of aster defects in model polar active matter†","authors":"Soumyadeep Mondal, Pankaj Popli and Sumantra Sarkar","doi":"10.1039/D4SM00788C","DOIUrl":"10.1039/D4SM00788C","url":null,"abstract":"<p >We numerically study the dynamics of topological defects in 2D polar active matter coupled to a conserved density field, which shows anomalous kinetics and defect distribution. The initial many-defect state relaxes by pair-annihilation of defects, which behave like Ostwald ripening on short timescales. However, defect coarsening is arrested at long timescales, and the relaxation kinetics becomes anomalously slow compared to the equilibrium state. Specifically, the number of defects in the active system approaches a steady state, following a power-law dependence in the rate of change of the inverse density. In contrast, in thermal equilibrium, the decay is exponential. Finally, we show that the anomalous coarsening of defects leads to unique patterns in the coupled density field, which is consistent with patterns observed in experiments on the actin cytoskeleton. These patterns can act as cell signaling platforms and may have important biological consequences.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 1","pages":" 77-86"},"PeriodicalIF":2.9,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Individual closed-loop control of micromotors by selective light actuation†","authors":"David P. Rivas, Max Sokolich and Sambeeta Das","doi":"10.1039/D4SM00810C","DOIUrl":"10.1039/D4SM00810C","url":null,"abstract":"<p >Control of individual micromotors within a group would allow for improved efficiency, greater ability to accomplish complex tasks, higher throughput, and increased adaptability. However, independent control of micromotors remains a significant challenge. Typical actuation techniques, such as chemical and magnetic, are uniform over the workspace and therefore cannot control one micromotor independently of the others. To address this challenge, we demonstrate a novel control method of applying a localized region of UV light that activates a single light-responsive TiO<small>₂</small> micromotor at a time. To achieve this, a digital micromirror device (DMD) was employed which is capable of highly precise localized illumination. To demonstrate this precise user-defined control, patterns of micromotors were created <em>via</em> selective actuation and magnetic steering. In addition, a closed-loop system was also developed which automates the guidance of individual micromotors to specified locations, illustrating the potential for more efficient and precise control of the micromotors.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 48","pages":" 9523-9527"},"PeriodicalIF":2.9,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11571050/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142646060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scale-dependent sharpening of interfacial fluctuations in shape-based models of dense cellular sheets","authors":"Haicen Yue, Charles R. Packard and Daniel M. Sussman","doi":"10.1039/D4SM00804A","DOIUrl":"10.1039/D4SM00804A","url":null,"abstract":"<p >The properties of tissue interfaces – between separate populations of cells, or between a group of cells and its environment – has attracted intense theoretical, computational, and experimental study. Recent work on shape-based models inspired by dense epithelia have suggested a possible “topological sharpening” effect, by which four-fold vertices spatially coordinated along a cellular interface lead to a cusp-like restoring force acting on cells at the interface, which in turn greatly suppresses interfacial fluctuations. We revisit these interfacial fluctuations, focusing on the distinction between short length scale reduction of interfacial fluctuations and long length scale renormalized surface tension. To do this, we implement a spectrally resolved analysis of fluctuations over extremely long simulation times. This leads to more quantitative information on the topological sharpening effect, in which the degree of sharpening depends on the length scale over which it is measured. We compare our findings with a Brownian bridge model of the interface, and close by analyzing existing experimental data in support of the role of short-length-scale topological sharpening effects in real biological systems.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 47","pages":" 9444-9453"},"PeriodicalIF":2.9,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142674590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Obstacle-enhanced spontaneous oscillation of confined active granules.","authors":"Xue Zhang, Yuxin Tian, Ran Ni, Yong Zhu, Luhui Ning, Peng Liu, Mingcheng Yang, Ning Zheng","doi":"10.1039/d4sm01027b","DOIUrl":"10.1039/d4sm01027b","url":null,"abstract":"<p><p>Spontaneous oscillation in particle numbers has been reported recently, in which two chambers connected by a narrow channel are alternately filled and emptied by self-propelled particles. The challenge in realizing the application of this oscillation lies in promotion of the oscillatory periodicity. By placing an asymmetric obstacle at an appropriate position near a channel opening, we can significantly improve the oscillation quality, which approaches the quality of an ideal oscillation. Additionally, we experimentally explore the relationship between the oscillation quality and various system parameters such as the obstacle position. Based on experimental observations, we incorporate a random noise into our previous model and properly reproduce the experimental results. The agreement between theory and experiment uncovers the mechanism of delicate competition between noise and unidirectional particle flow in influencing the oscillation quality. Our findings provide new insights for the optimization of the oscillation quality, expand the conventional rectification capability of the ratchet effect due to the obstacle, and make it possible for spontaneous oscillation to serve as a reliable source for rhythmic signals.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142612849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reversible pH-responsive supramolecular aggregates from viologen based amphiphiles – a molecular design perspective†","authors":"Redhills L. Narendran and Archita Patnaik","doi":"10.1039/D4SM00695J","DOIUrl":"10.1039/D4SM00695J","url":null,"abstract":"<p >pH responsive self-assembled supramolecular systems in water hold tremendous promise spanning across the various realms of science and technology. Herein, we report the design and synthesis of benzyl viologen (BV) based amphiphiles and their ability to form pH responsive aggregates with a water soluble anionic dye (electron donor), a polyelectrolyte (PE), and a surfactant. To counter the low solubility of viologen derivatives, β-cyclodextrin (β-CD) was employed as a solubility promoter and the host–guest complexes were characterized by NMR spectroscopy. The impacts of increasing the number of benzyl units on (i) the water solubility of viologens, (ii) the response of the aggregates of viologens with pyranine, PE, and surfactants towards pH, and (iii) the influence of β-CD on the pH-responsive nature of BV–pyranine, BV–PE, BV–surfactant, <em>etc.</em> were investigated. Apart from improving the solubility of viologens, β-CD also imparted pH-responsive dissolution/aggregation behavior to the viologen–anionic polyelectrolyte and viologen–anionic surfactant complexes. The pH switchable behaviour of the soft supramolecular aggregates in water was rationalized in light of a delicate balance prevailing between multiple non-covalent interactions. Based on the results, we propose an elegant molecular design principle to generate pH responsive colloidal aggregates from amphiphiles and oppositely charged molecular systems.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 47","pages":" 9391-9403"},"PeriodicalIF":2.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142646172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solvent-free confinement of ordered microparticle monolayers: effect of host substrate and pattern symmetry†","authors":"Ignaas S. M. Jimidar, Mitch T. J. de Waard, Gijs Roozendaal and Kai Sotthewes","doi":"10.1039/D4SM01196A","DOIUrl":"10.1039/D4SM01196A","url":null,"abstract":"<p >The self-organisation of individual suspended colloids into ordered structures that can be mediated by confinement has garnered interest recently. Despite the push for solvent reduction for sustainability reasons, the comprehension and development of solvent-free assembly methods remain largely unaddressed. In this study, we explore the effect of confinement without rigid geometrical constraints, <em>i.e.</em>, wall-less confinement on the assembly of monodisperse PMMA powder microspheres (diameters of 3 μm and 10 μm) on fluorocarbon-patterned heterogeneous substrates using a solvent-free rubbing assembly approach. Our findings reveal that the PMMA microspheres self-align on the fluorocarbon patterns, adapting to various geometrical shapes of these patterns through symmetry matching. The assembly process is driven by triboelectric charging and elastic properties of the microspheres and substrates. Moreover, we observe that the host substrate and the particle and pattern size ratio significantly influence the ordering of the microparticles on the fluorocarbon patterns. Ultimately, we demonstrate the successful use of fluorocarbon patterns to assemble tunable crystal patterns on rigid substrates, which typically do not exhibit any ordering.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 47","pages":" 9413-9423"},"PeriodicalIF":2.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/sm/d4sm01196a?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142646174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A dynamical system approach to relaxation in glass-forming liquids†","authors":"Jack F. Douglas, Qi-Lu Yuan, Jiarui Zhang, Hao Zhang and Wen-Sheng Xu","doi":"10.1039/D4SM00976B","DOIUrl":"10.1039/D4SM00976B","url":null,"abstract":"<p >The “classical” thermodynamic and statistical mechanical theories of Gibbs and Boltzmann are both predicated on axiomatic assumptions whose applicability is hard to ascertain. Theoretical objections and an increasing number of observed deviations from these theories have led to sustained efforts to develop an improved mathematical and physical foundation for them, and the search for appropriate extensions that are generally applicable to condensed materials at low temperatures (<em>T</em>) and high material densities where the assumptions of these theories start to become particularly questionable. These theoretical efforts have largely focused on minimal models of condensed material systems, such as the Fermi–Ulam–Pasta–Tsingou model, and other simplified models of condensed materials that are amenable to numerical and analytic treatments and that can serve to illuminate essential features of relaxation processes in condensed materials under conditions approaching integrable dynamics where clear departures from classical thermodynamics and dynamics can be generally expected. These studies indicate an apparently general multi-step relaxation process, corresponding to an initial “fast” relaxation process (termed the fast β-relaxation in the context of cooled liquids), followed by a longer “equipartition time”, namely, the α-relaxation time <em>τ</em><small>_α</small> in the context of cooled liquids. This relaxation timescale can be enormously longer than the fast β-relaxation time <em>τ</em><small>_β</small> so that <em>τ</em><small>_α</small> is the primary parameter governing the rate at which the material comes into equilibrium, and thus is a natural focus of theoretical attention. Since the dynamics of these simplified dynamical systems, originally intended as simplified models of real crystalline materials exhibiting anharmonic interactions, greatly resemble the observed relaxation dynamics of both heated crystals and cooled liquids, we adapt this dynamical system approach to the practical matter of estimating relaxation times in both cooled liquids and crystals at elevated temperatures, which we identify as weakly non-integrable dynamical systems.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 46","pages":" 9140-9160"},"PeriodicalIF":2.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/sm/d4sm00976b?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142602456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A multi-scale framework for predicting α-cyclodextrin assembly on polyethylene glycol axles†","authors":"Cameron D. Smith, Chenfeng Ke and Wenlin Zhang","doi":"10.1039/D4SM01048E","DOIUrl":"10.1039/D4SM01048E","url":null,"abstract":"<p >Controlling the distribution of rings on polymer axles, such as α-cyclodextrin (αCD) on polyethylene glycol (PEG), is paramount in imparting robust mechanical properties to slide-ring gels and polyrotaxane-based networks. Previous experiments demonstrated that the functionalization of polymer ends could modulate the coverage of αCDs on PEG. To explore the design rule, we propose a multi-scale framework for predicting αCD assembly on bare and functionalized PEG. Our approach combines all-atom molecular dynamics with two-dimensional (2D) umbrella sampling to compute the free energy landscapes of threading αCDs onto PEG with ends functionalized by various moieties. Together with the predicted free energy landscapes and a lattice treatment for αCD and polymer diffusion in dilute solutions, we construct a kinetic Monte Carlo (kMC) model to predict the number and intra-chain distribution of αCDs along the polymer axle. Our model predicts the effects of chain length, concentration, and threading barrier on the supramolecular structure of end-functionalized polypseudorotaxane. With simple modifications, our approach can be extended to explore the design rule of polyrotaxane-based materials with advanced network architectures.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 45","pages":" 9068-9082"},"PeriodicalIF":2.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/sm/d4sm01048e?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142602457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interfacial viscoelasticity in oscillating drops of cyclodextrin–surfactant aqueous solution: experiments and theory","authors":"J. Roberto Romero-Arias, Alberto S. Luviano, Miguel Costas, Aurora Hernández-Machado and Rafael A. Barrio","doi":"10.1039/D4SM01007H","DOIUrl":"10.1039/D4SM01007H","url":null,"abstract":"<p >We present experiments involving oscillating droplets in aqueous cyclodextrin–surfactant solutions. In these experiments, α-cyclodextrin (αCD) and anionic surfactants exhibit remarkable viscoelasticity at the liquid/air interface, with dilatational modulus varying across orders of magnitude. This rheological response depends on the concentrations of different complexes in the solution, particularly of the 2 : 1 inclusion complexes formed by two αCD molecules (αCD<small>₂</small>), and one surfactant (S). We propose a model that describes the distribution of these complexes on the droplet surface using a free energy approach, accounting for dipole–dipole interactions. The results of the model reproduce the interfacial behavior of the viscoelastic modulus and phase shift in excellent agreement with the data, clearly indicating that dipole–dipole interactions determine and control the viscoelastic properties of the drops.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 46","pages":" 9240-9248"},"PeriodicalIF":2.9,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142612845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanical properties of soft hydrogels: assessment by scanning ion-conductance microscopy and atomic force microscopy†","authors":"Tatiana N. Tikhonova, Yuri M. Efremov, Vasilii S. Kolmogorov, Aleksei P. Iakovlev, Nikolay N. Sysoev, Peter S. Timashev, Victor V. Fadeev, Alexander S. Tivtikyan, Sergey V. Salikhov, Petr V. Gorelkin, Yuri E. Korchev, Alexander S. Erofeev and Evgeny A. Shirshin","doi":"10.1039/D4SM00966E","DOIUrl":"10.1039/D4SM00966E","url":null,"abstract":"<p >The growing interest in biomimetic hydrogels is due to their successful applications in tissue engineering, 3D cell culturing and drug delivery. The major characteristics of hydrogels include swelling, porosity, degradation rate, biocompatibility, and mechanical properties. Poor mechanical properties can be regarded as the main limitation for the use of hydrogels in tissue engineering, and advanced techniques for its precise evaluation are of interest. The current research aims to demonstrate the suitability of scanning ion conductance microscopy (SICM) for assessing the stiffness of various hydrogels – Fmoc-FF peptide hydrogel, polyacrylamide and gelatin, – which differ by two orders of magnitude in Young's modulus (<em>E</em>). We provide a direct comparison between SICM measurements and atomic force microscopy (AFM) data, the latter being a widely used method for assessing the mechanical properties of scaffolds. The results of these methods showed good agreement, however, for materials with various stiffness two SICM-based approaches – application of hydrostatic pressure and application of intrinsic force – should be used. For hydrogels with Young's modulus of more than 2.5 kPa the application of SICM using hydrostatic pressure is recommended, whereas for soft materials with <em>E</em> ∼ 200–400 Pa the technique using intrinsic force can also be applied. We have shown that SICM and AFM methods can be used for the evaluation of the mechanical properties of soft hydrogels with nanometer resolution, while SICM is a completely non-invasive method, which requires a minimum influence on the sample structure.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" 47","pages":" 9464-9474"},"PeriodicalIF":2.9,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142680020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}