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Skin-mountable microelectronics are garnering substantial interest for various promising applications including human-machine interfaces, biointegrated devices, and personalized medicine. However, it remains a critical challenge to develop e-skins to mimic the human somatosensory system in full working range. Here, we present a multifunctional e-skin system with a heterostructured configuration that couples vinyl-hybrid-silica nanoparticle (VSNP)–modified polyacrylamide (PAM) hydrogel with two-dimensional (2D) MXene through nano-bridging layers of polypyrrole nanowires (PpyNWs) at the interfaces, featuring high toughness and low hysteresis, in tandem with controlled crack generation and distribution. The multidimensional configurations endow the e-skin with an extraordinary working range (2800%), ultrafast responsiveness (90 ms) and resilience (240 ms), good linearity (800%), tunable sensing mechanisms, and excellent reproducibility. In parallel, this e-skin platform is capable of detecting, quantifying, and remotely monitoring stretching motions in multiple dimensions, tactile pressure, proximity sensing, and variations in temperature and light, establishing a promising platform for next-generation smart flexible electronics.

With their unique ability to differentiate into all cell types, embryonic stem (ES) cells hold great therapeutic promise. To improve the efficiency of embryoid body (EB)-mediated ES cell differentiation, we studied murine EBs on the basis of their size and found that EBs with an intermediate size (diameter 100 -300 m) are the most proliferative, hold the greatest differentiation potential, and have the lowest rate of cell death. In an attempt to promote the formation of this subpopulation, we surveyed several biocompatible substrates with different surface chemical parameters and identified a strong correlation between hydrophobicity and EB development. Using self-assembled monolayers of various lengths of alkanethiolates on gold substrates, we directly tested this correlation and found that surfaces that exhibit increasing hydrophobicity enrich for the intermediate-size EBs. When this approach was applied to the human ES cell system, similar phenomena were observed. Our data demonstrate that hydrophobic surfaces serve as a platform to deliver uniform EB populations and may significantly improve the efficiency of ES cell differentiation.hydrophobicity ͉ self-assembled monolayers ͉ serum-free differentiation T he potential of embryonic stem (ES) cells to differentiate into all specialized cell types has made them attractive models for studying the mechanisms of lineage commitment and has opened pathways for regenerative medicine (1). Various in vitro strategies have been developed for differentiation of ES cells into populations of specific cell types (2). Of these strategies, the formation of three-dimensional cell aggregates known as embryoid bodies (EBs) is a common and critical intermediate to the induction of lineage-specific differentiation (3, 4). In addition, lineage differentiation programs within the EB closely resemble lineage commitment in vivo in the developing embryo, further highlighting the importance of the ES cell-EB culture system (5-8).Although EBs can be generated through several methodologies, the suspension culture technique allows for easy access to the cultured EBs and can be scaled for expansion (9). In this method, EBs are formed when ES cells are removed from feeder contact and dispersed on low-attachment tissue culture plates, supplemented by culture medium absent of key factors necessary for the maintenance of undifferentiated ES cell growth. Lowattachment tissue culture plates typically use neutral, hydrophilic hydrogels to prevent protein adsorption and subsequent cell attachment, facilitating the initial aggregation of ES cells that is critical to EB formation (10). The cellular aggregates formed by this procedure will develop simple EBs that consist of an outer layer of endoderm cells within 2-4 days (3). At this point, two differentiation strategies can be applied. If suspension culture is continued, simple EBs will differentiate further to form cystic EBs that typically contain an inner layer of columnar ectodermlike cells and that accumulate fluid in the interior of the struct...

An efficient nonviral platform for high-throughput and subcellular precision targeted intracellular delivery of nucleic acids in cell culture based on magnetic nanospears is reported. These magnetic nanospears are made of Au/Ni/Si (∼5 μm in length with tip diameters <50 nm) and fabricated by nanosphere lithography and metal deposition. A magnet is used to direct the mechanical motion of a single nanospear, enabling precise control of position and three-dimensional rotation. These nanospears were further functionalized with enhanced green fluorescent protein (eGFP)-expression plasmids via a layer-by-layer approach before release from the underlying silicon substrate. Plasmid functionalized nanospears are guided magnetically to approach target adherent U87 glioblastoma cells, penetrating the cell membrane to enable intracellular delivery of the plasmid cargo. After 24 h, the target cell expresses green fluorescence indicating successful transfection. This nanospear-mediated transfection is readily scalable for the simultaneous manipulation of multiple cells using a rotating magnet. Cell viability >90% and transfection rates >80% were achieved, which exceed conventional nonviral intracellular methods. This approach is compatible with good manufacturing practices, circumventing barriers to the translation and clinical deployment of emerging cellular therapies.

Stem cell technologies, especially patient‐specific, induced stem cell pluripotency and directed differentiation, hold great promise for changing the landscape of medical therapies. Proper exploitation of these methods may lead to personalized organ transplants, but to regenerate organs, it is necessary to develop methods for assembling differentiated cells into functional, organ‐level tissues. The generation of three‐dimensional human tissue models also holds potential for medical advances in disease modeling, as full organ functionality may not be necessary to recapitulate disease pathophysiology. This is specifically true of lung diseases where animal models often do not recapitulate human disease. Here, we present a method for the generation of self‐assembled human lung tissue and its potential for disease modeling and drug discovery for lung diseases characterized by progressive and irreversible scarring such as idiopathic pulmonary fibrosis (IPF). Tissue formation occurs because of the overlapping processes of cellular adhesion to multiple alveolar sac templates, bioreactor rotation, and cellular contraction. Addition of transforming growth factor‐β1 to single cell‐type mesenchymal organoids resulted in morphologic scarring typical of that seen in IPF but not in two‐dimensional IPF fibroblast cultures. Furthermore, this lung organoid may be modified to contain multiple lung cell types assembled into the correct anatomical location, thereby allowing cell‐cell contact and recapitulating the lung microenvironment. Our bottom‐up approach for synthesizing patient‐specific lung tissue in a scalable system allows for the development of relevant human lung disease models with the potential for high throughput drug screening to identify targeted therapies. Stem Cells Translational Medicine 2017;6:622–633

Deficiencies in either lamin B1 or lamin B2 cause both defective migration of cortical neurons in the developing brain and reduced neuronal survival. The neuronal migration abnormality is explained by a weakened nuclear lamina that interferes with nucleokinesis, a nuclear translocation process required for neuronal migration. In contrast, the explanation for impaired neuronal survival is poorly understood. We hypothesized that the forces imparted on the nucleus during neuronal migration result in nuclear membrane (NM) ruptures, causing interspersion of nuclear and cytoplasmic contents—and ultimately cell death. To test this hypothesis, we bredLmnb1-deficient mice that express a nuclear-localized fluorescentCrereporter. Migrating neurons within the cortical plate of E18.5Lmnb1-deficient embryos exhibited NM ruptures, evident by the escape of the nuclear-localized reporter into the cytoplasm and NM discontinuities by electron microscopy. The NM ruptures were accompanied by DNA damage and cell death. The NM ruptures were not observed in nonmigrating cells within the ventricular zone. NM ruptures, DNA damage, and cell death were also observed in culturedLmnb1−/−andLmnb2−/−neurons as they migrated away from neurospheres. To test whether mechanical forces on the cell nucleus are relevant to NM ruptures in migrating neurons, we examined culturedLmnb1−/−neurons when exposed to external constrictive forces (migration into a field of tightly spaced silicon pillars). As the cells entered the field of pillars, there were frequent NM ruptures, accompanied by DNA damage and cell death.

Advances in gene editing are leading to new medical interventions where patients’ own cells are used for stem cell therapies and immunotherapies. One of the key limitations to translating these treatments to the clinic is the need for scalable technologies for engineering cells efficiently and safely. Toward this goal, microfluidic strategies to induce membrane pores and permeability have emerged as promising techniques to deliver biomolecular cargo into cells. As these technologies continue to mature, there is a need to achieve efficient, safe, nontoxic, fast, and economical processing of clinically relevant cell types. We demonstrate an acoustofluidic sonoporation method to deliver plasmids to immortalized and primary human cell types, based on pore formation and permeabilization of cell membranes with acoustic waves. This acoustofluidic-mediated approach achieves fast and efficient intracellular delivery of an enhanced green fluorescent protein-expressing plasmid to cells at a scalable throughput of 200,000 cells/min in a single channel. Analyses of intracellular delivery and nuclear membrane rupture revealed mechanisms underlying acoustofluidic delivery and successful gene expression. Our studies show that acoustofluidic technologies are promising platforms for gene delivery and a useful tool for investigating membrane repair.

While three-dimensional (3D) configurable hierarchical nanostructures have wide ranging applications in electronics, biology, and optics, finding scalable approaches remains a challenge. We report a robust and general strategy called multiple-patterning nanosphere lithography (MP-NSL) for the fabrication of periodic 3D hierarchical nanostructures in a highly scalable and tunable manner. This nanofabrication technique exploits the selected and repeated etching of polymer nanospheres that serve as resists and that can be shaped in parallel for each processing step. The application of MP-NSL enables the fabrication of periodic, vertically aligned Si nanotubes at the wafer scale with nanometer-scale control in three dimensions including outer/inner diameters, heights/hole-depths, and pitches. The MP-NSL method was utilized to construct 3D periodic hierarchical hybrid nanostructures such as multilevel solid/hollow nanotowers where the height and diameter of each level of each structure can be configured precisely as well as 3D concentric plasmonic nanodisk/nanorings with tunable optical properties on a variety of substrates.