Exosomes are nanoscale extracellular vesicles that play an important role in many biological processes, including intercellular communications, antigen presentation, and the transport of proteins, RNA, and other molecules. Recently there has been significant interest in exosome-related fundamental research, seeking new exosomebased biomarkers for health monitoring and disease diagnoses. Here, we report a separation method based on acoustofluidics (i.e., the integration of acoustics and microfluidics) to isolate exosomes directly from whole blood in a label-free and contactfree manner. This acoustofluidic platform consists of two modules: a microscale cell-removal module that first removes larger blood components, followed by extracellular vesicle subgroup separation in the exosome-isolation module. In the cell-removal module, we demonstrate the isolation of 110-nm particles from a mixture of micro-and nanosized particles with a yield greater than 99%. In the exosome-isolation module, we isolate exosomes from an extracellular vesicle mixture with a purity of 98.4%. Integrating the two acoustofluidic modules onto a single chip, we isolated exosomes from whole blood with a blood cell removal rate of over 99.999%. With its ability to perform rapid, biocompatible, label-free, contactfree, and continuous-flow exosome isolation, the integrated acoustofluidic device offers a unique approach to investigate the role of exosomes in the onset and progression of human diseases with potential applications in health monitoring, medical diagnosis, targeted drug delivery, and personalized medicine. extracellular vesicles | exosomes | blood-borne vesicles | surface acoustic waves | acoustic tweezers

The impact of a pre‐existing rift fabric on normal fault array evolution during a subsequent phase of lithospheric extension is investigated using 2‐D and 3‐D seismic reflection, and borehole data from the northern Horda Platform, Norwegian North Sea. Two fault populations are developed: (i) a population comprising relatively tall (>2 km), N‐S‐striking faults, which have >1.5 km of throw. These faults are up to 60 km long, penetrate down into crystalline basement and bound the eastern margins of 6–15 km wide half‐graben, which contain >3 km of pre‐Jurassic, likely Permo–Triassic, but possibly Devonian syn‐rift strata; and (ii) a population comprising vertically restricted (<1 km), NW‐SE‐striking faults, which are more closely spaced (0.5–5 km), have lower displacements (30–100 m) and not as long (2–10 km) as those in the N–S‐striking population. The NW‐SE‐striking population typically occurs between the N‐S‐striking population, and may terminate against or cross‐cut the larger structures. NW–SE‐striking faults do not bound pre‐Jurassic half‐graben and are largely restricted to the Jurassic‐to‐Cretaceous succession. Seismic‐stratigraphic observations, and the stratigraphic position of the fault tips in both fault populations, allow us to reconstruct the Late Jurassic‐to‐Early Cretaceous growth history of the northern Horda Platform fault array. We suggest the large, N‐S‐striking population was active during the Permo–Triassic and possibly earlier (Devonian?), before becoming inactive and buried during the Early and Middle Jurassic. After a period of relative tectonic quiescence, the N‐S‐striking, pre‐Jurassic fault population propagated through the Early‐Middle Jurassic cover and individual fault systems rapidly (within <10 Ma) established their maximum length in response to Late Jurassic extension. These fault systems became the dominant structures in the newly formed fault array and defined the locations of the main, Late Jurassic‐to‐Early Cretaceous, syn‐rift depocentres. Late Jurassic extension was also accommodated by broadly synchronous growth of the NW‐SE‐striking fault population; the eventual death of this population occurred in response to the localization of strain onto the N–S‐striking fault population. Our study demonstrates that the inheritance of a pre‐existing rift fabric can influence the geometry and growth of individual fault systems and the fault array as a whole. On the basis of observations made in this study, we present a conceptual model that highlights the influence of a pre‐existing rift fabric on fault array evolution in polyphase rifts.

During intraerythrocytic development, Plasmodium falciparum exports proteins that interact with the host cell plasma membrane and subplasma membrane-associated spectrin network. Parasiteexported proteins modify mechanical properties of host RBCs, resulting in altered cell circulation. In this work, optical tweezers experiments of cell mechanical properties at normal physiological and febrile temperatures are coupled, for the first time, with targeted gene disruption techniques to measure the effect of a single parasite-exported protein on host RBC deformability. We investigate Pf155/Ring-infected erythrocyte surface antigen (RESA), a parasite protein transported to the host spectrin network, on deformability of ring-stage parasite-harboring human RBCs. Using a set of parental, gene-disrupted, and revertant isogenic clones, we found that RESA plays a major role in reducing deformability of host cells at the early ring stage of parasite development, but not at more advanced stage. We also show that the effect of RESA on deformability is more pronounced at febrile temperature, which ring-stage parasite-harboring RBCs can be exposed to during a malaria attack, than at normal body temperature. malaria ͉ erythrocyte ͉ membrane shear modulus ͉ spectrin ͉ cytoskeleton A fter Plasmodium falciparum merozoite invasion of a human RBC, the parasite differentiates and multiplies for 48 h, leading to rupture of the parasitized RBC (Pf-RBCs) and release of new merozoites in the blood circulation. Throughout this 48-h period, several parasite proteins are introduced into the RBC plasma membrane and submembranous protein skeleton, thereby modifying a range of structural and functional properties of the Pf-RBCs (1-4). The best documented changes occur as P. falciparum matures to the trophozoite (24-36 h) and schizont (36-48 h) stages, when Pf-RBCs display decreased membrane deformability (2-6), become spherical, and develop cytoadherence properties responsible for parasite sequestration in the postcapillary venules of different organs (7,8). In contrast, during early parasite development, ring-stage (0-24 h after invasion) Pf-RBCs preserve their biconcave shape, can circulate in peripheral blood (9), and thus are exposed to the spleen red pulp. Ring-stage Pf-RBCs may pass through this spleen compartment, be expelled from circulation, or return to the circulation once the parasite has been removed (10). Although the relative importance of these different processes and their underlying mechanisms are not fully understood, it is likely that altered deformability of ring-stage Pf-RBCs (11) plays a crucial role in determining Pf-RBCs spleen processing.Introduction of parasite components within the Pf-RBC membrane and cortical cytoskeleton begins soon after RBC invasion, as demonstrated for the well characterized parasite protein Pf155/Ring-infected erythrocyte surface antigen (RESA) (12). This protein is discharged by the invading merozoite and exported to the Pf-RBC membrane where, once phosphorylated, it interacts with the spectrin n...

Upon infection and development within human erythrocytes, P. falciparum induces alterations to the infected RBC morphology and bio-mechanical properties to eventually rupture the host cells through parasitic and host derived proteases of cysteine and serine families. We used previously reported broad-spectrum inhibitors (E64d, EGTA-AM and chymostatin) to inhibit these proteases and impede rupture to analyze mechanical signatures associated with parasite escape. Treatment of late-stage iRBCs with E64d and EGTA-AM prevented rupture, resulted in no major RBC cytoskeletal reconfiguration but altered schizont morphology followed by dramatic re-distribution of three-dimensional refractive index (3D-RI) within the iRBC. These phenotypes demonstrated several-fold increased iRBC membrane flickering. In contrast, chymostatin treatment showed no 3D-RI changes and caused elevated fluctuations solely within the parasitophorous vacuole. We show that E64d and EGTA-AM supported PV breakdown and the resulting elevated fluctuations followed non-Gaussian pattern that resulted from direct merozoite impingement against the iRBC membrane. Optical trapping experiments highlighted reduced deformability of the iRBC membranes upon rupture-arrest, more specifically in the treatments that facilitated PV breakdown. Taken together, our experiments provide novel mechanistic interpretations on the role of parasitophorous vacuole in maintaining the spherical schizont morphology, the impact of PV breakdown on iRBC membrane fluctuations leading to eventual parasite escape and the evolution of membrane stiffness properties of host cells in which merozoites were irreversibly trapped, recourse to protease inhibitors. These findings provide a comprehensive, previously unavailable, body of information on the combined effects of biochemical and biophysical factors on parasite egress from iRBCs.

SignificanceSmall unilamellar vesicles formed via self-assembly of phospholipids or block copolymers have been investigated in the context of human physiology and biomedical research. Here, we present both energetics and thermodynamics analyses that incorporate nonlinear elasticity to predict, in a unique manner, the limiting size and size distribution of vesicles as well as to identify the conditions for the formation of stable open vesicles, disks, and closed spherical vesicles. In addition to providing a comprehensive understanding of vesicle formation, the framework presented here may be adapted to develop tools for in vivo liquid biopsies and to elucidate the biophysical features of extracellular vesicles, thus suggesting new approaches to diagnostics and therapeutics for cancer and other diseases.

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SignificancePlant leaves and flower petals in nature exhibit a wide variety of complex 3D shapes. Formation of these shapes has largely been studied from genetic and biomolecular viewpoints, overlooking contributions from biophysical factors such as mechanical stress and deformation. By means of computational simulations and quantitative analyses of the growth strains in live plant organs, we develop fundamental mechanistic insights into how nature invokes mechanics in the evolution of four commonly found shapes in plant organs by differential growth. We also demonstrate how these common shapes can be synthetically reproduced in hydrogel using this mechanistic understanding. Our study provides a broad scientific framework for rationalizing plant organ morphogenesis, but also provides pathways for generating bioinspired 3D architectures in soft materials.

We investigate the biophysical characteristics of healthy human red blood cells (RBCs) traversing microfluidic channels with cross-sectional areas as small as 2.7 × 3 μm. We combine single RBC optical tweezers and flow experiments with corresponding simulations based on dissipative particle dynamics (DPD), and upon validation of the DPD model, predictive simulations and companion experiments are performed in order to quantify cell deformation and pressure–velocity relationships for different channel sizes and physiologically relevant temperatures. We discuss conditions associated with the shape transitions of RBCs along with the relative effects of membrane and cytosol viscosity, plasma environments, and geometry on flow through microfluidic systems at physiological temperatures. In particular, we identify a cross-sectional area threshold below which the RBC membrane properties begin to dominate its flow behavior at room temperature; at physiological temperatures this effect is less profound.