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Directional cell migration in dense three-dimensional (3D) environments critically depends upon shape adaptation and is impeded depending on the size and rigidity of the nucleus. Accordingly, the nucleus is primarily understood as a physical obstacle; however, its pro-migratory functions by stepwise deformation and reshaping remain unclear. Using atomic force spectroscopy, time-lapse fluorescence microscopy and shape change analysis tools, we determined the nuclear size, deformability, morphology and shape change of HT1080 fibrosarcoma cells expressing the Fucci cell cycle indicator or being pre-treated with chromatin-decondensating agent TSA. We show oscillating peak accelerations during migration through 3D collagen matrices and microdevices that occur during shape reversion of deformed nuclei (recoil), and increase with confinement. During G1 cell-cycle phase, nucleus stiffness was increased and yielded further increased speed fluctuations together with sustained cell migration rates in confinement when compared to interphase populations or to periods of intrinsic nuclear softening in the S/G2 cell-cycle phase. Likewise, nuclear softening by pharmacological chromatin decondensation or after lamin A/C depletion reduced peak oscillations in confinement. In conclusion, deformation and recoil of the stiff nucleus contributes to saltatory locomotion in dense tissues. This article is part of a discussion meeting issue ‘Forces in cancer: interdisciplinary approaches in tumour mechanobiology’.

Hypo- and hyperthermia affect both primary and secondary hemostasis; however, there are controversial data concerning platelet activation and the underlying mechanisms under hypo- and hyperthermia. The discrepancies in the data could be partly explained by different approaches to hemostatic reactions analysis. We applied a new LaSca-TMF laser particle analyzer for a simultaneous fluorescence and laser scattering analysis of platelet responses at different temperatures. Human platelets were activated by ADP in a wide range of temperatures, and platelet transformations (e.g., a shape change reaction, aggregation and clot formation) and the intracellular calcium concentration ([Ca2+]i) were analyzed by LaSca-TMF and confocal microscopy. The platelet shape change reaction gradually increased with a rising temperature. The platelet aggregation strongly decreased at low ADP concentrations with the augmentation of the temperature and was independent of the temperature at high ADP concentrations. In contrast, the clotting time decreased with a temperature increase. Similar to the aggregation response, a rise in [Ca2+]i triggered by low ADP concentrations was higher under hypothermic conditions and the differences were independent of the temperature at high ADP concentrations. We showed that the key reactions of cellular hemostasis are differentially regulated by temperature and demonstrated for the first time that an accelerated aggregation under hypothermic conditions directly correlated with an increased level in [Ca2+]i in platelets.

Magnetically driven small‐scale soft robots are promising for applications in biomedicine, due to their fast, programmable deformation, and remote, untethered actuation to accomplish complicated tasks. Although diverse materials and designs have been proposed for magnetic soft robots with programmable shape transformation, it is still challenging to produce strong actuation by a small magnetic field. Inspired by arthropod species, magnetic soft millirobots with joint structures by 3D printing hydrogels have been developed. The joints can turn the bending deformation into the folding deformation, with the jointed region deforming locally. Different from homogeneous bending deformation, such local deformation allows larger motions of robots and reduces the overall energy consumption at the same time. Through experiments and numerical simulations, it is shown that the magnetic arthropod millirobots are capable of performing multimodal locomotion and programmed shape transformation, such as move, flip, catch, carry, and release. Finally, ex vivo experiments of removing a foreign object from porcine organs (e.g., aorta, stomach, and intestine) are presented to demonstrate the potential surgery application of magnetic arthropod millirobots. Magnetic arthropod millirobots have been fabricated by 3D‐printed hydrogels. Inspired by jointed limbs of arthropod species, joint geometry is studied and introduced into the magnetic arthropod millirobots. The six‐armed millirobot demonstrates multimodal locomotion, including move, flip, catch, carry, and release. Foreign body removal is performed in porcine organs ex vivo using the six‐armed millirobots.

This paper presents a numerical strategy for the shape change analysis of spine biotensegrity models in multi-directional modes. The formulation of incremental equilibrium equations and optimization problem for shape change analysis via the forced elongation of cables to achieve the target coordinates of the monitored nodes of spine biotensegrity models are presented. The distance between the monitored nodes and the target coordinates is chosen as the objective function which is minimized subject to inequality constraints on member axial forces and cable forced elongation. Three spine biotensegrity models were analyzed to validate the effectiveness of the proposed method. The deformation characteristics of the Class-1 four-stage biotensegrity models mimicking the natural curvature of the human spine were investigated. A highly successful rate in achieving the target coordinates was observed in a total of 258 analysis cases, with percentages of 99.9%, 99.9% and 98.9% for shape change analysis involving uni-, bi- and tri-directional modes, respectively. The results show that the spine biotensegrity models have more flexibility in undergoing bending in comparison with axial deformation. With the established shape change strategy, the flexibility and versatility of the movement of spine biotensegrity models can be further studied for potential application in the shape change control of deployable structures together with the use of IoT.

With the improvement of medical and health care level in our society, the demand for antibacterial materials is increasing. In this work, we prepared the antibacterial materials by loading silver nanoparticles (AgNPs) on the dialdehyde cellulose (DAC) with in-situ synthesis method. DAC was prepared by pretreating cellulose fiber with sodium metaperiodate (NaIO 4 ) to convert the hydroxyl group into aldehyde group, and then reacted with silver nitrate (AgNO 3 ) to obtain AgNPs loaded on DAC. UV–Vis results show that the characteristic absorption peak of AgNPs at 428 nm appeared in the AgNPs-loaded-DAC. It was observed by SEM that the spherical AgNPs were distributed uniformly on the DAC surface without obvious flocculation. The color of DAC was not changed significantly, indicating that a small amount of AgNPs was loaded. In addition, sodium citrate (Na 3 C 6 H 5 O 7 ) was added in the reaction of DAC and AgNO 3 and its effect on the formation of AgNPs was studied. The results demonstrated that the color of DAC turned deeper and finally dark yellow with reaction time extended. When the reaction time was 60 h, the spherical AgNPs were gradually grown and transformed into triangular prism on the DAC surface. The antibacterial properties of AgNPs showed inhibition zones of 4.90 mm and 7.35 mm (60 h) against Gram-negative ( E. coli ) and Gram-positive ( S. aureus ), respectively, which increased by 40.00% and 14.85% compared with spherical AgNPs (2.5 h) obtained without Na 3 C 6 H 5 O 7 . The research of AgNPs-loaded cellulose-based materials promotes the development prospect of new nano-antibacterial materials. Graphical abstract

Among post-lithium ion battery technologies, rechargeable chemistries with Zn anodes bear notable technological promise owing to their high theoretical energy density, lower manufacturing cost, availability of raw materials and inherent safety. However, Zn anodes, when employed in aqueous electrolytes, suffer from hydrogen evolution, passivation, and shape changes. Alternative electrolytes can help tackle these issues, preserving the green and safe characteristics of aqueous-based ones. Deep eutectic solvents (DESs) are promising green and low-cost non-aqueous solvents for battery electrolytes. Specifically, the cycling of Zn anodes in DESs is expected to be reversible, chiefly owing to their dendrite-suppression capability. Nevertheless, apart from a few studies on Zn plating, insight into the cathodic–anodic electrochemistry of Zn in DESs is still very limited. In view of developing DES-based battery electrolytes, it is crucial to consider that a potential drawback might be their low ionic conductivity. Water molecules can be added to the eutectic mixtures by up to 40% to increase the diffusion coefficient of the electroactive species and lower the electrolyte viscosity without destroying the eutectic nature. In this study, we address the electrochemistry of Zn in two different hydrated DESs (ChU and ChEG with ~30% H2O). Fundamental electrokinetic and electrocrystallization studies based on cyclic voltammetry and chronoamperometry at different cathodic substrates are completed with a galvanostatic cycling test of Zn|Zn symmetric CR2032 coin cells, SEM imaging of electrodes and in situ SERS spectroscopy. This investigation concludes with the proposal of a specific DES/H2O/ZnSO4-based electrolyte that exhibits optimal functional performance, rationalized on the basis of fundamental electrochemical data, morphology evaluation and modeling of the cycling response.

In recent years, four-dimensional (4D) fabrication has emerged as a powerful technology capable of revolutionizing the field of tissue engineering. This technology represents a shift in perspective from traditional tissue engineering approaches, which generally rely on static—or passive—structures (e.g., scaffolds, constructs) unable of adapting to changes in biological environments. In contrast, 4D fabrication offers the unprecedented possibility of fabricating complex designs with spatiotemporal control over structure and function in response to environment stimuli, thus mimicking biological processes. In this review, an overview of the state of the art of 4D fabrication technology for the obtainment of cellularized constructs is presented, with a focus on shape-changing soft materials. First, the approaches to obtain cellularized constructs are introduced, also describing conventional and non-conventional fabrication techniques with their relative advantages and limitations. Next, the main families of shape-changing soft materials, namely shape-memory polymers and shape-memory hydrogels are discussed and their use in 4D fabrication in the field of tissue engineering is described. Ultimately, current challenges and proposed solutions are outlined, and valuable insights into future research directions of 4D fabrication for tissue engineering are provided to disclose its full potential.

The criteria for the assessment of the form change in the process of direct profiling of workpieces , applying the stretching method with a rupture are developed, methods for their calculation are proposed with allowance for the volume of the redistributed metal and energy costs for deformation. The nature of the functional connection of these criteria of shape change assessment with the work of deformation is determined.

Four-dimensional textiles are textiles that can change shape or function over time by the influence of a stimulus, mainly force and heat. In this review, the focus is on 4D textiles made by additive manufacturing which is built on the concept of 4D printing. A literature survey in Web of Science and Scopus was carried out, which resulted in 29 contributions on additive manufacturing on pre-stressed textiles. In this paper, an overview of materials, production technologies and testing methods is given. The concepts of form giving and shape change transferred to 4D textiles are classified. The influencing factors on the properties of the material structure are presented. The main focus of the literature lies in defining process and material properties for improving the adhesion. Only limited research has been conducted on simulating the material behavior. Ideas for applications exist but no research has been conducted on real applications. Therefore, the challenges are identified, and future research directions are derived.

Minimizing unintended granulocyte activation while measuring functional responsiveness is essential, as the use of external probes, antibodies, or fluorescent dyes can potentially alter cellular responsiveness. To address this, we employed an antibody-free flow cytometry approach that measures forward scatter (FSC) to detect variations in cell-size, morphology, and shape; some key indicators of neutrophil and eosinophil activation. Human peripheral blood neutrophils, containing contaminating eosinophils, were isolated using discontinuous Percoll gradients and pre-treated with receptor antagonists [e.g., cyclosporin-H (an FPR1 antagonist) and CP105696 (a BLT1 receptor antagonist)] prior to stimulation with agonists such as fMLF (an FPR1 agonist) and LTB 4 (a BLT1 agonist). Furthermore, fMLF stimulation resulted in a loss of CD62L and an increase in CD11b expression along with an increase in intracellular ROS production compared to control, as analysed using flow cytometry. Imaging flow cytometry, together with FSC analysis, enabled assessment of cell polarization and associated morphological changes. Importantly, autofluorescence-based gating allowed for the identification of contaminating eosinophils within the mixed granulocyte population, allowing parallel assessment of shape-change in both neutrophils and eosinophils in response to the same ligands. Stimulation of neutrophils with fMLF resulted in distinct FSC shifts compared to unstimulated controls across all flow cytometers tested, which were inhibited by cyclosporin-H, but not CP105696. Morphological analysis confirmed these changes corresponded with increased cell area and perimeter and decreased circularity, hallmarks of cell polarisation. Additionally, selective activation of eosinophils (but not neutrophils) by eotaxin, and dual activation of both cell types by the arachidonic acid metabolite 5-oxo-ETE, were confirmed through specific gating strategies. Taken together, these findings support the use of FSC-based flow cytometry as a rapid, scalable and effective method for evaluating granulocyte polarisation and screening candidate therapeutics targeting immune cell activation in disease contexts.