Immune Cell-Based Microrobots for Remote Magnetic Actuation, Antitumor Activity, and Medical Imaging.

Translating medical microrobots into clinics requires tracking, localization, and performing assigned medical tasks at target locations, which can only happen when appropriate design, actuation mechanisms, and medical imaging systems are integrated into a single microrobot. Despite this, these parameters are not fully considered when designing macrophage-based microrobots. This study presents living macrophage-based microrobots that combine macrophages with magnetic Janus particles coated with FePt nanofilm for magnetic steering and medical imaging and bacterial lipopolysaccharides for stimulating macrophages in a tumor-killing state. The macrophage-based microrobots combine wireless magnetic actuation, tracking with medical imaging techniques, and antitumor abilities. These microrobots are imaged under magnetic resonance imaging and optoacoustic imaging in soft-tissue-mimicking phantoms and ex vivo conditions. Magnetic actuation and real-time imaging of microrobots are demonstrated under static and physiologically relevant flow conditions using optoacoustic imaging. Further, macrophage-based microrobots are magnetically steered toward urinary bladder tumor spheroids and imaged with a handheld optoacoustic device, where the microrobots significantly reduce the viability of tumor spheroids. The proposed approach demonstrates the proof-of-concept feasibility of integrating macrophage-based microrobots into clinic imaging modalities for cancer targeting and intervention, and can also be implemented for various other medical applications.

Dry Synthesis of Pure and Ultrathin Nanoporous Metallic Films.

Nanoporous metals possess unique properties attributed to their high surface area and interconnected nanoscale ligaments. They are mostly fabricated by wet synthetic methods that are not universal to various metals and not free from impurities due to solution-based etching processes. Here, we demonstrate that the plasma treatment of metal nanoparticles formed by physical vapor deposition is a general route to form such films with many metals including the non-noble ones. The resultant nanoporous metallic films are free of impurities and possess highly curved ligaments and nanopores. The metal films are ultrathin, yet remarkably robust and very well connected, and thus are highly promising for various applications such as transparent conducting electrodes.

Remotely Guided Immunobots Engaged in Anti-Tumorigenic Phenotypes for Targeted Cancer Immunotherapy.

Building medical microrobots from the body's own cells may circumvent the biocompatibility concern and hence presents more potential in clinical applications to improve the possibility of escaping from the host defense mechanism. More importantly, live cells can enable therapeutically relevant functions with significantly higher efficiency than synthetic systems. Here, live immune cell-derived microrobots from macrophages, i.e., immunobots, which can be remotely steered with externally applied magnetic fields and directed toward anti-tumorigenic (M1) phenotypes, are presented. Macrophages engulf the engineered magnetic decoy bacteria, composed of 0.5 µm diameter silica Janus particles with one side coated with anisotropic FePt magnetic nanofilm and the other side coated with bacterial lipopolysaccharide (LPS). This study demonstrates the torque-based surface rolling locomotion of the immunobots along assigned trajectories inside blood plasma, over a layer of endothelial cells, and under physiologically relevant flow rates. The immunobots secrete signature M1 cytokines, IL-12 p40, TNF-α, and IL-6, and M1 cell markers, CD80 and iNOS, via toll-like receptor 4 (TLR4)-mediated stimulation with bacterial LPS. The immunobots exhibit anticancer activity against urinary bladder cancer cells. This study further demonstrates such immunobots from freshly isolated primary bone marrow-derived macrophages since patient-derivable macrophages may have a strong clinical potential for future cell therapies in cancer.

Sensing Capabilities of Single Nanowires Studied with Correlative In Situ Light and Electron Microscopy.

Modern devices based on modular designs require versatile and universal sensor components which provide an efficient, sensitive, and compact measurement unit. To improve the space capacity of devices, miniaturized building elements are needed, which implies a turning away from conventional microcantilevers toward nanoscale cantilevers. Nanowires can be seen as high-quality resonators and offer the opportunity to create sensing devices on small scales. To use such a one-dimensional nanostructure as a resonant cantilever, a precise characterization based on the fundamental properties is needed. We present a correlative electron and light microscopy approach to characterize the pressure and environment sensing capabilities of single nanowires by analyzing their resonance behavior in situ. The high vacuum in electron microscopes enables the characterization of the intrinsic vibrational properties and the maximum quality factor. To analyze the damping effect caused by the interaction of the gas molecules with the excited nanowire, the in situ resonance measurements have been performed under non-high-vacuum conditions. For this purpose, single nanowires are mounted in a specifically designed compact gas chamber underneath the light microscope, which enables direct observation of the resonance behavior and evaluation of the quality factor with dependence of the applied gas atmosphere (He, N2, Ar, Air) and pressure level. By using the resonance vibration, we demonstrate the pressure sensing capability of a single nanowire and examine the molar mass of the surrounding atmosphere. Together this shows that even single nanowires can be utilized as versatile nanoscale gas sensors.

MondoA drives malignancy in B-ALL through enhanced adaptation to metabolic stress.

Cancer cells are in most instances characterized by rapid proliferation and uncontrolled cell division. Hence, they must adapt to proliferation-induced metabolic stress through intrinsic or acquired antimetabolic stress responses to maintain homeostasis and survival. One mechanism to achieve this is reprogramming gene expression in a metabolism-dependent manner. MondoA (also known as Myc-associated factor X-like protein X-interacting protein [MLXIP]), a member of the MYC interactome, has been described as an example of such a metabolic sensor. However, the role of MondoA in malignancy is not fully understood and the underlying mechanism in metabolic responses remains elusive. By assessing patient data sets, we found that MondoA overexpression is associated with worse survival in pediatric common acute lymphoblastic leukemia (ALL; B-precursor ALL [B-ALL]). Using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) and RNA-interference approaches, we observed that MondoA depletion reduces the transformational capacity of B-ALL cells in vitro and dramatically inhibits malignant potential in an in vivo mouse model. Interestingly, reduced expression of MondoA in patient data sets correlated with enrichment in metabolic pathways. The loss of MondoA correlated with increased tricarboxylic acid cycle activity. Mechanistically, MondoA senses metabolic stress in B-ALL cells by restricting oxidative phosphorylation through reduced pyruvate dehydrogenase activity. Glutamine starvation conditions greatly enhance this effect and highlight the inability to mitigate metabolic stress upon loss of MondoA in B-ALL. Our findings give novel insight into the function of MondoA in pediatric B-ALL and support the notion that MondoA inhibition in this entity offers a therapeutic opportunity and should be further explored.

Class I histone deacetylases (HDAC) critically contribute to Ewing sarcoma pathogenesis.

BACKGROUND: Histone acetylation and deacetylation seem processes involved in the pathogenesis of Ewing sarcoma (EwS). Here histone deacetylases (HDAC) class I were investigated. METHODS: Their role was determined using different inhibitors including TSA, Romidepsin, Entinostat and PCI-34051 as well as CRISPR/Cas9 class I HDAC knockouts and HDAC RNAi. To analyze resulting changes microarray analysis, qRT-PCR, western blotting, Co-IP, proliferation, apoptosis, differentiation, invasion assays and xenograft-mouse models were used. RESULTS: Class I HDACs are constitutively expressed in EwS. Patients with high levels of individual class I HDAC expression show decreased overall survival. CRISPR/Cas9 class I HDAC knockout of individual HDACs such as HDAC1 and HDAC2 inhibited invasiveness, and blocked local tumor growth in xenograft mice. Microarray analysis demonstrated that treatment with individual HDAC inhibitors (HDACi) blocked an EWS-FLI1 specific expression profile, while Entinostat in addition suppressed metastasis relevant genes. EwS cells demonstrated increased susceptibility to treatment with chemotherapeutics including Doxorubicin in the presence of HDACi. Furthermore, HDACi treatment mimicked RNAi of EZH2 in EwS. Treated cells showed diminished growth capacity, but an increased endothelial as well as neuronal differentiation ability. HDACi synergizes with EED inhibitor (EEDi) in vitro and together inhibited tumor growth in xenograft mice. Co-IP experiments identified HDAC class I family members as part of a regulatory complex together with PRC2. CONCLUSIONS: Class I HDAC proteins seem to be important mediators of the pathognomonic EWS-ETS-mediated transcription program in EwS and in combination therapy, co-treatment with HDACi is an interesting new treatment opportunity for this malignant disease.

Crystallography of γ'-Fe4N formation in single-crystalline α-Fe whiskers.

Gaseous nitriding of steel and iron can significantly improve their properties, for example corrosion resistance, fatigue endurance and tribological properties. In order to obtain a better understanding of the early stages of formation of the initial cubic primitive γ'-Fe4N, the mechanism and crystallography of the α-γ' phase transformation was investigated under simplified conditions. Single-crystal α-Fe whiskers were nitrided at 823 K and a nitriding potential of 0.7 atm-1/2 for 20 min. The resulting microstructure and phases, as well as the crystallographic orientation of crystallites belonging to a particular phase, were characterized by scanning electron microscopy coupled with electron backscatter diffraction. The habit planes were investigated by single- and two-surface trace analysis. The α-Fe whiskers partly transform into γ'-Fe4N, where γ' grows mainly in a plate-like morphology. An orientation relationship close to the rational Pitsch orientation relationship and {0.078 0.432 0.898}α and {0.391 0.367 0.844}γ' as habit planes were predicted by the phenomenological theory of martensite crystallography (PTMC), adopting a {101}α〈101〉α shear system for lattice invariant strain, which corresponds to a {1 1 1}γ'〈1 12〉γ' shear system in γ'. The encountered orientation relationship and the habit planes exhibit excellent agreement with predictions from the PTMC, although the transformation definitely requires diffusion. The γ' plates mainly exhibit one single internally untwinned variant. The formation of additional variants due to strain accommodation, as well as the formation of a complex microstructure, was suppressed to a considerable extent by the fewer mechanical constraints imposed on the transforming regions within the iron whiskers as compared to the situation at the surface of bulk samples.

Plastic Forming of Metals at the Nanoscale: Interdiffusion-Induced Bending of Bimetallic Nanowhiskers.

Controlled plastic forming of nanoscale metallic objects by applying mechanical load is a challenge, since defect-free nanocrystals usually yield at near theoretical shear strength, followed by stochastic dislocation avalanches that lead to catastrophic failure or irregular, uncontrolled shapes. Herein, instead of mechanical load, we utilize chemical stress from imbalanced interdiffusion to manipulate the shape of nanowhiskers. Bimetallic Au-Fe nanowhiskers with an ultrahigh bending strength were synthesized employing the molecular beam epitaxy technique. The one-sided Fe coating on the defect-free, single-crystalline Au nanowhisker exhibited both single- and polycrystalline regions. Annealing the bimetallic nanowhiskers at elevated temperatures led to gradual change of curvature and irreversible bending. At low homological temperatures at which grain boundary diffusion is a dominant mode of mass transport this irreversible bending was attributed to the grain boundary Kirkendall effect during the diffusion of Au along the grain boundaries in the Fe layer. At higher temperatures and longer annealing times, the bending was dominated by intensive bulk diffusion of Fe into the Au nanowhisker, accompanied by a significant migration of the Au-Fe interphase boundary toward the Fe layers. The irreversible bending was caused by the concentration dependence of the lattice parameter of the Au(Fe) alloy and by the volume effect associated with the interphase boundary migration. The results of this study demonstrate a high potential of chemical interdiffusion in the controlled plastic forming of ultrastrong metal nanostructures. By design of the thickness, microstructure, and composition of the coating as well as the parameters of heat treatment, bimetallic nanowhiskers can be bent in a controlled manner.

Magnetic quantification of single-crystalline Fe and Co nanowires via off-axis electron holography.

Investigating the local micromagnetic structure of ferromagnetic nanowires (NWs) at the nanoscale is essential to study the structure-property relationships and can facilitate the design of nanostructures for technology applications. Herein, we synthesized high-quality iron and cobalt NWs and investigated the magnetic properties of these NWs using off-axis electron holography. The Fe NWs are about 100 nm in width and a few micrometers in length with a preferential growth direction of [100], while the Co NWs have a higher aspect-ratio with preferential crystal growth along the [110] direction. It is noted that compact passivation surface layers of oxides protect these NWs from further oxidation, even after nearly two years of exposure to ambient conditions; furthermore, these NWs display homogeneous ferromagnetism along their axial direction revealing the domination of shape anisotropy on magnetic behavior. Importantly, the average value of magnetic induction strengths of Fe NWs (2.07 {±} 0.10 T) and Co NWs (1.83 {±} 0.15 T) is measured to be very close to the respective theoretical value, and it shows that the surface oxide layers do not affect the magnetic moments in NWs. Our results provide a useful synthesis approach for the fabrication of single-crystalline, defect-free metal NWs and give insight into the micromagnetic properties in ferromagnetic NWs based on the transmission electron microscopy measurements.

Combined Inhibition of Epigenetic Readers and Transcription Initiation Targets the EWS-ETS Transcriptional Program in Ewing Sarcoma.

BACKGROUND: Previously, we used inhibitors blocking BET bromodomain binding proteins (BRDs) in Ewing sarcoma (EwS) and observed that long term treatment resulted in the development of resistance. Here, we analyze the possible interaction of BRD4 with cyclin-dependent kinase (CDK) 9. METHODS: Co-immunoprecipitation experiments (CoIP) to characterize BRD4 interaction and functional consequences of inhibiting transcriptional elongation were assessed using drugs targeting of BRD4 or CDK9, either alone or in combination. RESULTS: CoIP revealed an interaction of BRD4 with EWS-FLI1 and CDK9 in EwS. Treatment of EwS cells with CDKI-73, a specific CDK9 inhibitor (CDK9i), induced a rapid downregulation of EWS-FLI1 expression and block of contact-dependent growth. CDKI-73 induced apoptosis in EwS, as depicted by cleavage of Caspase 7 (CASP7), PARP and increased CASP3 activity, similar to JQ1. Microarray analysis following CDKI-73 treatment uncovered a transcriptional program that was only partially comparable to BRD inhibition. Strikingly, combined treatment of EwS with BRD- and CDK9-inhibitors re-sensitized cells, and was overall more effective than individual drugs not only in vitro but also in a preclinical mouse model in vivo. CONCLUSION: Treatment with BRD inhibitors in combination with CDK9i offers a new treatment option that significantly blocks the pathognomonic EWS-ETS transcriptional program and malignant phenotype of EwS.

High capacity rock salt type Li2MnO3-δ thin film battery electrodes.

Recent investigations of layered, rock salt and spinel-type manganese oxides in composite powder electrodes revealed the mutual stabilization of the Li-Mn-O compounds during electrochemical cycling. A novel approach of depositing such complex compounds as an active cathode material in thin-film battery electrodes is demonstrated in this work. It shows the maximum capacity of 226 mA h g-1 which is superior in comparison to that of commercial LiMn2O4 powder as well as thin films. Reactive ion beam sputtering is used to deposit films of a Li2MnO3-δ composition. The method allows for tailoring of the active layer's crystal structure by controlling the oxygen partial pressure during deposition. Electron diffractometry reveals the presence of layered monoclinic and defect rock salt structures, the former transforms during cycling and results in thin films with extraordinary electrochemical properties. X-ray photoelectron spectroscopy shows that a large amount of disorder on the cation sub-lattices has been incorporated in the structure, which is beneficial for lithium migration and cycle stability.

Retraction Note: Increased survival and cell cycle progression pathways are required for EWS/FLI1-induced malignant transformation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Superior Magnetic Performance in FePt L10 Nanomaterials.

The discovery of the high maximum energy product of 59 MGOe for NdFeB magnets is a breakthrough in the development of permanent magnets with a tremendous impact in many fields of technology. This value is still the world record, for 40 years. This work reports on a reliable and robust route to realize nearly perfectly ordered L10 -phase FePt nanoparticles, leading to an unprecedented energy product of 80 MGOe at room temperature. Furthermore, with a 3 nm Au coverage, the magnetic polarization of these nanomagnets can be enhanced by 25% exceeding 1.8 T. This exceptional magnetization and anisotropy is confirmed by using multiple imaging and spectroscopic methods, which reveal highly consistent results. Due to the unprecedented huge energy product, this material can be envisaged as a new advanced basic magnetic component in modern micro and nanosized devices.

Transition of Deformation Mechanisms in Single-Crystalline Metallic Nanowires.

Twinning and dislocation slip are two competitive deformation mechanisms in face-centered cubic (FCC) metals. For FCC metallic nanowires (NWs), the competition between these mechanisms was found to depend on loading direction and material properties. Here, using in situ transmission electron microscopy tensile tests and molecular dynamics simulations, we report an additional factor, cross-sectional shape, that can affect the competition between the deformation mechanisms in single-crystalline FCC metallic NWs. For a truncated rhombic cross-section, the extent of truncation determines the competition. Specifically, a transition from twinning to localized dislocation slip occurs with increasing extent of truncation. Theoretical and simulation results indicate that the energy barriers for twinning and dislocation slip depend on the cross-sectional shape of the NW. The energy barrier for twinning is proportional to the change of surface energy associated with the twinning. Thus, the transition of deformation modes can be attributed to the change of surface energy as a function of the cross-sectional shape.

Hydrogen embrittlement in metallic nanowires.

Although hydrogen embrittlement has been observed and extensively studied in a wide variety of metals and alloys, there still exist controversies over the underlying mechanisms and a fundamental understanding of hydrogen embrittlement in nanostructures is almost non-existent. Here we use metallic nanowires (NWs) as a platform to study hydrogen embrittlement in nanostructures where deformation and failure are dominated by dislocation nucleation. Based on quantitative in-situ transmission electron microscopy nanomechanical testing and molecular dynamics simulations, we report enhanced yield strength and a transition in failure mechanism from distributed plasticity to localized necking in penta-twinned Ag NWs due to the presence of surface-adsorbed hydrogen. In-situ stress relaxation experiments and simulations reveal that the observed embrittlement in metallic nanowires is governed by the hydrogen-induced suppression of dislocation nucleation at the free surface of NWs.

In Situ Generated Gold Nanoparticles on Active Carbon as Reusable Highly Efficient Catalysts for a C sp 3 -C sp 3 Stille Coupling.

Gold nanoparticle catalysts are important in many industrial production processes. Nevertheless, for traditional C sp 2 -C sp 2 cross-coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form C sp 3 -C sp 3 bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, which allowed for convenient catalyst recovery and reuse. The present study is a rare case where a gold metal catalyst is superior to Pd catalysts in a cross-coupling reaction of an organic halide and an organometallic reagent.

Peptide-Induced Biomineralization of Tin Oxide (SnO2) Nanoparticles for Antibacterial Applications.

Recently, there has been growing attention and effort to search for new microbicidal drugs which present different mode of action from those already existing, as an alternative to the global threat of fungal and bacterial multi drug resistance (MDR). Here we propose biological synthesis of SnO2 nanoparticles using mammalian cells as an economic and ecofriendly platform. This presents a novel biogenic method for SnO2 synthesis using metal binding peptides extracted from MCF-7 human cancer cells, which induces the biomineralization of SnO2 nanoparticles. A series of electron donor functional groups and metal binding sites in these peptides reacts with Sn2+ ions and directs the growth of SnO2 nanoparticles without addition of toxic redox and capping agents in the reaction system. Since peptides present reactive sites in aqueous solution at room temperature, a facile reaction environment can be easily achieved. Furthermore, by tuning the reactants' concentration and pH, the size, shape and 3D-structures of SnO2 nanoparticles can be controlled. Peptides also ensure biocompatibility, and SnO2 nanoparticles provide antibacterial properties, which broadens their applications in biomedical fields.

3D Nanofabrication of High-Resolution Multilayer Fresnel Zone Plates.

Focusing X-rays to single nanometer dimensions is impeded by the lack of high-quality, high-resolution optics. Challenges in fabricating high aspect ratio 3D nanostructures limit the quality and the resolution. Multilayer zone plates target this challenge by offering virtually unlimited and freely selectable aspect ratios. Here, a full-ceramic zone plate is fabricated via atomic layer deposition of multilayers over optical quality glass fibers and subsequent focused ion beam slicing. The quality of the multilayers is confirmed up to an aspect ratio of 500 with zones as thin as 25 nm. Focusing performance of the fabricated zone plate is tested toward the high-energy limit of a soft X-ray scanning transmission microscope, achieving a 15 nm half-pitch cut-off resolution. Sources of adverse influences are identified, and effective routes for improving the zone plate performance are elaborated, paving a clear path toward using multilayer zone plates in high-energy X-ray microscopy. Finally, a new fabrication concept is introduced for making zone plates with precisely tilted zones, targeting even higher resolutions.

Matrix mineralization controls gene expression in osteoblastic cells.

Osteoblasts are adherent cells, and under physiological conditions they attach to both mineralized and non-mineralized osseous surfaces. However, how exactly osteoblasts respond to these different osseous surfaces is largely unknown. Our hypothesis was that the state of matrix mineralization provides a functional signal to osteoblasts. To assess the osteoblast response to mineralized compared to demineralized osseous surfaces, we developed and validated a novel tissue surface model. We demonstrated that with the exception of the absence of mineral, the mineralized and demineralized surfaces were similar in molecular composition as determined, for example, by collagen content and maturity. Subsequently, we used the human osteoblastic cell line MG63 in combination with genome-wide gene set enrichment analysis (GSEA) to record and compare the gene expression signatures on mineralized and demineralized surfaces. Assessment of the 5 most significant gene sets showed on mineralized surfaces an enrichment exclusively of genes sets linked to protein synthesis, while on the demineralized surfaces 3 of the 5 enriched gene sets were associated with the matrix. Focusing on these three gene sets, we observed not only the expected structural components of the bone matrix, but also gene products, such as HMCN1 or NID2, that are likely to act as temporal migration guides. Together, these findings suggest that in osteoblasts mineralized and demineralized osseous surfaces favor intracellular protein production and matrix formation, respectively. Further, they demonstrate that the mineralization state of bone independently controls gene expression in osteoblastic cells.