Nature Materials

The development of novel mechanomedicine technologies critically depends on the ability to administer a well-defined mechanical dosage to cells. Unlike chemical cues, mechanical signals are vectorial rather than scalar, making their precise delivery inherently complex. When external mechanical stimuli are applied to cells seeded on a flat substrate, the mechanical dose experienced by each cell varies depending on its orientation and conformation, rendering consistent and effective mechano-modulation impractical. Here, we introduce a substrate-guided mechanical stimulation strategy that standardizes mechanical dose delivery at the population level by controlling cell orientation. Using nanogrooved PDMS substrates integrated into a uniaxial stretching platform, we induced coherent alignment of NIH3T3 fibroblasts and their mechanosensitive subcellular structures along the direction of applied strains. Cells cultured on flat or nanogrooved substrates were subjected to sustained uniaxial strains of 8% and 29%, and their responses were quantified in real time by live-cell fluorescence imaging. Nanogroove-induced alignment enabled uniform transmission of substrate strain to focal adhesions and the cytoskeleton, resulting in coherent and quantifiable nuclear deformation across the cell population. In contrast, cells on flat substrates exhibited orientation-dependent deformation modes that canceled out at the population level, leading to heterogeneous and attenuated responses. While cellular adaptation to sustained strain was primarily governed by strain magnitude, substrate-guided alignment markedly reduced cell-to-cell variability in mechanical signal perception. Overall, this work establishes cell alignment as a key parameter for standardizing mechanical dose delivery and improving the reproducibility of mechanobiology experiments and the design of mechanically active biomaterials.

Cell motility drives spatial pattern formation across diverse biological systems. Here, we engineer Escherichia coli motility in semi-solid agar to control Voronoi patterns in two and three dimensions, partitioning space into regions closest to their respective inoculation seeds. Consistent with our reaction-diffusion model, we observed that collisions between expansion fronts generate either biomass depletion (''gaps'') or accumulation (''anti-gaps''), governed by the relative diffusion rates of bacteria and nutrients. By engineering strains with distinct expansion rates and tuneable motility, and by integrating these experimental data into a dynamic Voronoi model, we achieved precise control over pattern geometry. This enabled the generation of gaps with varying widths, curved boundaries, asymmetric structures, seedless regions, and complex composite patterns. Together, these findings establish bacterial Voronoi patterns as a programmable platform for engineering multicellular spatial organization, with potential applications in synthetic biology and materials science.

During tumor growth and progression, cancer cells are exposed to sustained physical confinement and volumetric compression that can alter cell volume, cytoskeletal organization, mechanotransduction, and invasive behavior. However, whether breast cancer cells retain a compression-induced mechanical memory after release from sustained volumetric compression, and how this memory influences subsequent migration and invasion, remains poorly understood. Here, by controlling cell volume using PEG - mediated volumetric compression, we investigated the compression and post-compression recovery responses of MCF-7 breast cancer cells. Cells were compressed for four days, followed by four days of recovery after PEG removal, and analyzed using daily morphological tracking, single-cell time-lapse imaging, F-actin and YAP staining, wound healing assays, and 3D spheroid invasion assays. We show that sustained volumetric compression shifts MCF-7 cells into a compact, jammed-like, low-motility state characterized by reduced morphodynamic remodeling, suppressed collective migration, and limited spheroid invasion. In contrast, post-compression recovery induces a distinct mechanobiological state marked by increased cell area and perimeter, altered single-cell trajectories, heterogeneous F-actin remodeling, enhanced YAP nuclear localization in enlarged recovered cells, accelerated wound closure, and increased spheroid invasion and cell dissemination. These findings suggest that prior volumetric compression can prime breast cancer cells for enhanced migration and invasion after stress release, supporting post-compression recovery as a form of mechanical memory that may contribute to tumor dissemination.

Cell shape changes during migration, division, or differentiation require the dynamic regulation of actin network mechanics. Actin crosslinkers are central to this regulation, controlling network connectivity and the transmission of contractile forces. A large diversity of crosslinkers exists, differing in length, domain structure, and binding kinetics, yet why cells deploy specific crosslinkers in a physiological context remains unclear. To bridge this gap, we developed a light-controlled actin crosslinker toolbox spanning three physiologically relevant lengths: ~9 nm (fascin-like), ~16 nm (fimbrin-like), and ~56 nm (alpha-actinin-like). Using magnetic pincher experiments and in silico modelling, we show that short and mid-length crosslinkers dynamically tune cortical stiffness and thickness in a density- and myosin-dependent manner, with short crosslinkers also driving pronounced stress-stiffening as the cortex is deformed. Strikingly, minute-scale activation reveals a length-dependent switch in cell behaviour: short crosslinkers cause cortical delamination, while long ones instead drive cell polarization and symmetry breaking. This switch can be overridden by perturbing actin turnover, which unlocks polarization in mid-length crosslinkers that otherwise delaminate. Crosslinker-induced polarization is not merely a local cortical event: it directs subsequent cell spreading, coupling a nanometre-scale molecular choice to a cell-scale decision about movement. Together, these findings establish a versatile optogenetic platform for manipulating actin crosslinking, and show that the cortex can encode a behavioural switch directly in its material architecture.

Surface curvature is a fundamental geometric cue in tissue morphogenesis, yet its role in guiding collective cell organization has remained elusive. Here, we show that curvature acts as a geometric control parameter that shapes supracellular alignment and chirality while modulating myogenic differentiation in myoblast tissues. Cells cultured on curved substrates self-organize into robust helical assemblies whose handedness is set, and can be reversed, by the sign of curvature: convex fibers produce right-handed helices, whereas concave channels invert the chirality. We identify a previously hidden clockwise bias in single-cell motion associated with the helical actin cytoskeleton. A minimal continuum theory coupling an effective chiral drive to curvature quantitatively captures the emergence and reversal of tissue-scale chiral alignment. On substrates with spatially varying curvature, local curvature gradients organize patterned multicellular architectures while preserving a global handedness. Curvature is also associated with myogenic state, with higher curvature linked to reduced or delayed differentiation. Together, these findings reveal how complex geometries shape the alignment, symmetry, and cellular state of living tissues.

Tissue mechanics influence diverse biological processes, yet directly linking stiffness measurements to spatially resolved molecular states in intact tissues remains challenging. Here we developed a paired-surface spatial mechanomics approach to map Young's modulus by nanoindentation on a fresh tissue surface and co-register the stiffness grid with 10x Genomics Visium HD spatial transcriptome bins from the immediately adjacent, parallel surface. Applied to the mouse ovary, which has spatially distinct compartments and undergoes extracellular matrix remodeling with cycle and age, the workflow generated >2,900 matched measurements across 21 regions of interest. Nanoindentation at 50-m grid spacing enabled millimeter-scale stiffness maps while balancing acquisition time in fresh tissues, with ~92 4-m transcriptome bins assigned to each stiffness value. Global and compartment-specific analyses associated stiffer regions with lower elastic fiber programs and higher inflammatory signaling, with age-dependent differences. This correlative strategy integrates experimentally measured mechanics with spatial omics in fresh tissues.

Early animal embryos undergo rapid cleavages that partition cytoplasmic volumes orders of magnitude larger than those of somatic cells1. Each division must reposition nuclei and centrosomes and distribute organelles within minutes, over distances up to hundreds of micrometers2. Cleavage furrows are positioned by microtubule asters3,4, but the mechanical mechanism for long-range transport of cytoplasmic components before cytokinesis was unknown. Here, we show that cytoplasm behaves as a locally switchable active material. Fluidization at the midplane allows bulk actomyosin to convert a local mechanical asymmetry into directed global flows of all components as a composite material. Using an actin-intact cycling Xenopus egg extract together with Xenopus and medaka embryos, we find that F-actin mechanically couples microtubule asters, organelles, nuclei and centrosomes into a gel-like composite that propagates forces over hundreds of micrometers. After mitosis, Aurora B kinase patterns a locally fluidized midplane, from which myosin-II contractility drives coherent cytoplasmic flows. A fluid dynamics model accounts for the observed flow geometry and rates. Our results reveal how local control of the material state of cytoplasm converts mitotic symmetry breaking into long-range intracellular transport and identify bulk actomyosin as the active stress generator that partitions embryonic cytoplasm as a composite gel.

Piconewton forces borne by individual proteins within complex assemblies underlie cell adhesion, migration, and tissue morphogenesis, yet remain difficult to image in living systems. Here, we introduce WHaloForce, a chemigenetic HaloTag-based tension sensor that converts force-dependent relief of tryptophan-mediated dye quenching into a fluorescence lifetime change. Optical tweezers revealed a switch-like unquenching transition near 5 pN, and the sensor responded reversibly to force changes in cells. WHaloForce enabled quantitative tension imaging of diverse force-bearing proteins (vinculin, E-cadherin, -catenin, and laminin) in mammalian cells, mouse tissue, and C. elegans. Bright synthetic dyes made tension measurements possible at endogenous expression levels. In C. elegans, vinculin and laminin showed opposite tension patterns between tissues, revealing distinct force-transmission routes through adhesions and the extracellular matrix. During ovulation, laminin tension accumulated over repeated stretch-relaxation cycles, scaling with cumulative loading history. WHaloForce thus offers a modular platform for imaging spatiotemporal tension patterns in living systems.

Epithelial tissues continuously remodel their curvature during morphogenesis, homeostasis, regeneration, and disease, yet experimental access to time-varying curvature remains limited. Here, we introduce CurvoChip, a pneumatically actuated microsystem that reversibly deforms confluent epithelial monolayers cultured on a 20-m elastic membrane into concave or convex geometries. The device operates either in a standard incubator or on a microscope stage and provides programmable control over pressure amplitude, direction, and cycling. Analytical scaling, finite-element simulations, and confocal profilometry establish predictable membrane deformation across the operating range, whereas cycling between -400 and +400 mbar for 120 cycles produces stable deflection without detectable drift or residual deformation. We further implement a three-dimensional surface-reconstruction and segmentation workflow to quantify cell and nuclear morphology on curved monolayers. Acute curvature induction produces a marked polarity-dependent response: convex deformation causes greater cell spreading and epithelial thinning than concave deformation, while nuclear projected area, thickness, and volume change in a direction- and position-dependent manner. These results show that epithelial architecture is sensitive not only to curvature magnitude but also to its orientation relative to the apico-basal axis. CurvoChip therefore provides an accessible platform for dissecting how epithelial tissues integrate dynamic geometric cues.

Tunneling nanotubes (TNTs) are actin-supported membrane bridges that mediate long-range intercellular communication and direct transfer of signaling molecules, organelles, and pathogenic cargo, yet the physicochemical mechanisms underlying their formation and organization remain poorly understood. Here we show that TNT-like intervesicular connections emerge from minimal physicochemical interactions between actin filaments and lipid membranes. Upon Mg2+ exposure, actin-encapsulating vesicles spontaneously generated actin bundle-embedded lipid nanotubes (AT-LNTs) that formed stable intervesicular networks. Mg2+ simultaneously induced actin polymerization, filament bundling, and electrostatic recruitment of F-actin to phosphatidylcholine membranes, enabling membrane tubulation without actin-binding proteins. Systematic perturbation of membrane phase, membrane tension, Mg2+ concentration, ionic strength, and actin concentration revealed that AT-LNT formation occurs only within a narrow physicochemical regime where membrane deformation and actin-membrane coupling are simultaneously permissive. The resulting AT-LNTs reproduced key structural and dynamic features of cellular TNTs, including bundled organization, helical unwinding, lumenal diffusion, and spontaneous bridging between synthetic vesicles and living cells. These findings establish a minimal biophysical framework for understanding the emergence of intercellular membrane connections in living systems and provide a foundation for engineering communication between synthetic and living cell.

Confined migration is essential for metastasis, yet how cells adapt their migratory and metabolic programs across stiffness-varying microenvironments remains unclear. We uncover a stiffness-dependent mechano-metabolic switch governing migration. In stiff microchannels, cells utilize the osmotic engine model (OEM), relying on NHE1 activity, front-polarization, and glycolysis. In soft microchannels, migration is OEM-independent and requires pyruvate-fueled oxidative phosphorylation (OxPHOS). This OxPHOS-driven motility depends on Arp3, {beta}1-integrin and integrin-linked kinase, which increase membrane tension in confinement that in turn triggers TRPM7-mediated calcium influx and RhoA-/myosin-II contractility. Activating and polarizing NHE1, via overexpression, hypoxia or elevated viscosity, restore OEM- and glycolysis-dependent migration in soft microchannels, bypassing the need for actin polymerization in vitro and in chick embryos. Mitochondria addition reinstates Arp3 polarization and enhances migration in NHE1-overexpressing cells, enabling engagement of both mechanisms in vitro and in zebrafish. These findings uncover a previously unrecognized mechano-metabolic link, revealing that intracellular rewiring overrides stiffness-dependent metabolic demands.

Sequence heterogeneity is a defining feature of cellular biomolecular condensates, yet how competing interaction motifs encode their thermodynamic stability, internal organization, and dynamics remains poorly understood. Here, we systematically tune the hydrophobicity mismatch between intrinsically disordered peptide pairs to establish sequence hydrophobicity as a programmable determinant of heterotypic condensate behaviour. We show that heterotypic condensates are thermodynamically more stable than homotypic ones having same average hydrophobicity through the cooperative interplay of short-range hydrophobic and long-range electrostatic interactions. Increasing hydrophobicity mismatch drives a composition-dependent transition from homogeneous condensates to core-shell architectures accompanied by pronounced spatial and dynamical heterogeneity, whereas reducing sequence disparity restores homogeneous organization and nearly uniform dynamics. Our results establish a direct molecular link between sequence chemistry, phase stability, condensate architecture, and transport dynamics, providing predictive design principles for engineering synthetic biomolecular condensates with programmable organization and material properties. TOC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/743201v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@12e7fborg.highwire.dtl.DTLVardef@13c31a0org.highwire.dtl.DTLVardef@de3453org.highwire.dtl.DTLVardef@3d4600_HPS_FORMAT_FIGEXP M_FIG C_FIG

The rise of antifungal resistance and limited antifungal drug classes creates an urgent need for biomaterials with localized, programmable activity. Here, we engineered curli nanofibers displaying the antifungal peptide heliomicin and unexpectedly discovered that wild-type CsgA itself exhibits intrinsic antifungal activity against Candida albicans, reducing fungal viability by approximately 2 log units. Heliomicin fusion enhanced this activity to a 3.5-log fungicidal reduction while preserving nanofiber self-assembly, hydrogel formation, mechanical properties, and 3D printability. Mechanistic analyses linked enhanced activity to membrane disruption and expansion of the cationic surface of CsgA. Heliomicin-CsgA hydrogels further reduced fungal burden and suppressed hyphal development in an ex vivo porcine skin infection model. These findings reveal that extracellular protein nanofibers can harbor intrinsic biological activities that can be uncovered and enhanced through protein engineering, establishing a strategy for developing intrinsically bioactive, programmable biomaterials for localized therapeutic applications against fungal pathogens and potentially other microbial infections.

Tau is a neuron-specific microtubule-associated protein that can self-associate into pathological insoluble aggregates or phase separate into condensates whose (patho)physiological role is debated. Recent studies suggest that intracellular surfaces can locally promote biomolecular condensation, even at low molecular concentrations. While microtubules in neurons provide an abundant tau-interaction surface, their role in tau phase separation remains unclear. Through a dialogue between experiments and theory, we demonstrate that tau forms multilayered condensates on microtubules at physiological concentrations via a prewetting-like transition. Concomitant tau-microtubule and tau-tau interactions explain the experimentally observed cooperative binding of the innermost tau layer directly adsorbed to the microtubule. The formation of this layer is dictated by the spacing of tubulin dimers within the microtubule lattice. Additional tau layers, driven by tau-tau interactions and independent of lattice spacing, are finite in thickness and unstable away from the microtubule surface. While the microtubule-adsorbed tau can selectively restrict proteins from the microtubule surface, the multilayered tau condensates can recruit tau interactors, such as RNA or soluble tubulin, highlighting the distinct roles of the condensate layers. Our results suggest that a prewetting-like transition constitutes a general physical mechanism for organizing liquid-like biomolecular layers of defined composition on charged intracellular surfaces.

Although topological defects in cell monolayers have been recognized as mechanical organizing centers in morphogenetic processes, the mechanism by which cells coordinate their motion at such defects and self-organize into higher-order structures remains elusive. Here, we report the formation of three-dimensional (3D) multicellular mounds in unconfined myoblast monolayers, at well-controlled vortex topological defects. Prior to the onset of bilayering, the vortex structure induces millimeter-scale cell flows converging toward the defect center. As a result, 3D cell mounds form at the defect core, layer-by-layer. These mounds grow by interlayer permeation sustained by the converging cell flows. At late stages, the bell shape of the structured mounds can be modeled with a dynamics driven by these converging flows. Our results therefore highlight the crucial role of integer topological defects in driving large-scale cell flows yielding the formation of highly ordered 3D tissues from a monolayer. We propose that similar mechanisms may be at play in certain morphogenetic and tumorigenic events.

As central executioners of cell death, caspases that activate exclusively in diseased cells would provide powerful and specific therapeutic agents. Natural caspase regulation exhibits two universal features that facilitate the engineering of such caspases: proximity-induced subunit assembly and modular separation of substrate recruitment from catalysis. Here, we take advantage of these features to engineer "Raspases," split effector caspases that conditionally reconstitute active complexes upon detection of mutant Ras, an oncogene altered in roughly a quarter of all cancers. When delivered as mRNA in lipid nanoparticles, Raspases selectively eliminate Ras-mutant human cancer lines while sparing wild-type cells. The system is built entirely from human protein domains, can be encoded as a single polyprotein, and can be adapted to trigger pyroptosis. Critically, Raspases match or exceed the potency of alternative Ras-targeting interventions in vitro. These results establish retargeted caspases as a generalizable sense-and-kill platform for selective elimination of diseased cells.

Spatial-omics workflows enable molecular analysis within tissue spatial context. Despite the prognostic value of tissue stiffness, these approaches have not incorporated direct, mechanical measurements. This omission reflects several challenges, including sample requirements, low throughput, specialized equipment, and complex data registration. Here, we introduce mechanoMaST (mechanics mapped to spatial transcriptomics), the first workflow to combine absolute mechanical measurements with spatial-omics. It pairs atomic force microscopy-based nanoindentation stiffness maps with spatial transcriptomics maps from adjacent tissue cryosections. The two modalities are then computationally co-registered to enable direct spatial correlation at 100 um resolution, with mapping accuracy quantified through error propagation, providing ground-truth mechanical data directly linked to spatial gene expression. We demonstrate mechanoMaST in human colorectal cancer liver metastasis, generating a spatial resource from 10 patients and revealing a four-gene stiffness signature. mechanoMaST is readily adaptable to other tissues across development and disease, and extendable to additional spatial-omics modalities in adjacent sections.

Delamination within stratified epithelia like the skin epidermis describes the detachment and upward motion of cells originating from the basal layer. Despite its fundamental importance for tissue development, homeostatic regeneration and repair, the mechanisms that drive delamination remain a longstanding open question. Upward motion follows cell shape changes, which are inherently driven by physical forces, but their role is elusive. Here, we investigate delamination in stratifying keratinocytes by combining imaging, force measurements and theoretical modeling. We identify a local change in force balance between differentiating cells and their environment as the key step initiating delamination. Within a homogeneous cell layer with apically polarized contractility, differentiation leads to actomyosin remodeling, redistributing cellular force exertion to the basal side. Such mechanical heterogeneity then results in differentiating cells experiencing and inward basal and outward apical forces that manifest in the formation of a +1 force defect and promote shape changes culminating in upward motion. Simultaneously, delaminating cells actively pull on their underlying neighbors, generating convergent tissue flows which close the basal layer below. Together, we propose a general physical description of delamination initiation, which may act across various multilayered epithelia.

The molecular programmability of nucleic acids has facilitated the development of architected DNA/RNA nanostructures and their applications in novel materials and technologies. We report how different types of DNA and RNA nanoaggregates, bundling digital information encoded into oligo libraries, can be formed by manipulating the ionic strength of the solution. As DNA or RNA suspensions are immersed in solutions of increasing salt concentrations, we observe the onset of aggregation. Further increase in ionic strength leads to the formation of stable, reproducible, and well-defined aggregates. We show that these nanoaggregates are kinetically trapped at room temperature, stably partition DNA libraries that encode image files, and support file-specific random access by bundling DNA libraries with unique address oligos. The nanoaggregate files can be disrupted and reformed into scrambled bundles using simple external fluid shear or temperature annealing, rapidly obfuscating the data. We term these nanoaggregates nucleic acid PACKeTs: Partitioned Aggregates of Colloidal DNA/RNA through Kinetic Trapping. Overall, the results demonstrate how gaining fundamental insights into ionic colloidal aggregation enables new forms of manipulation of DNA and RNA libraries. This understanding could lead to novel functionalities including kinetically trapped data partitioning, random access, and data encryption or obfuscation.

Visual neuroscience requires precise spatiotemporal projection of optical stimulation onto the retina, especially in experimental mouse models. However, in vivo patterned stimulation in mice is profoundly hindered by the extreme optical power and severe anatomical aberrations of the eye. Consequently, visual stimulation relies mainly on unverifiable, open-loop approximations that often lack spatial precision. Here, we introduce a closed-loop, spatially modulated stimulation platform that overcomes these barriers. By integrating a digital micromirror device (DMD) with electronically tunable lenses (ETLs) and a real-time, fundus camera-guided focus optimization module, we directly verify the location of patterned stimuli on the retina while dynamically correcting for chromatic and geometric defocus. This platform delivers quantitatively verified static and dynamic patterned stimuli to the living retina with lateral resolutions as fine as 6.7 {micro}m. Guided by ray-tracing optical analysis, our work establishes a technological foundation that enables highly reproducible, cellular-scale interrogations of the visual pathway.