Featured
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Letter |
Hippo/YAP-mediated rigidity-dependent motor neuron differentiation of human pluripotent stem cells
Although human pluripotent stem cells (hPSCs) can be used to regenerate neural tissues, inefficient protocols and poorly defined culture conditions have hindered their use. It is now shown that soft, micropatterned culture substrates can induce hPSCs to differentiate into motor neurons with significantly improved yields and purity in comparison to rigid substrates, and that such mechanotransductive process involves the Hippo/YAP pathway and phosphorylation of the intracellular protein Smad.
- Yubing Sun
- , Koh Meng Aw Yong
- & Jianping Fu
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Article |
Universal process-inert encoding architecture for polymer microparticles
The use of encoded microparticles in industrial settings is hampered by issues of scalability, decoding robustness and encoding density. Now, easily decodable microparticles with spatially patterned rare-earth upconversion nanocrystals, exponentially scalable encoding capacities and ultralow decoding false-alarm rates that are insensitive to harsh processing environments and can be used in practical applications such as durable anti-counterfeiting labels and multiplexed bioassays are reported.
- Jiseok Lee
- , Paul W. Bisso
- & Patrick S. Doyle
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Article |
Injectable and bioresponsive hydrogels for on-demand matrix metalloproteinase inhibition
Excessive activity of matrix metalloproteinases (MMPs) occurs in many diseases; however, the systemic administration of MMP inhibitors can cause undesirable, off-target effects and hence, clinical translation has been hampered. Now, injectable polysaccharide-based hydrogels are shown to enable the localized delivery of an inhibitor of MMP following the hydrogels’ degradation in response to MMP activity. This targeted approach shows efficacy in a myocardial infarction model in large animals.
- Brendan P. Purcell
- , David Lobb
- & Jason A. Burdick
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Progress Article |
Microimaging of transient guest profiles to monitor mass transfer in nanoporous materials
Microimaging techniques, such as interference and infrared microscopy, can be used as a tool to directly monitor guest profiles within nanoporous materials. Observation of the variation in these profiles leads to unprecedented insight into transport phenomena, including intracrystalline diffusion and surface permeation.
- Jörg Kärger
- , Tomas Binder
- & Jens Weitkamp
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Article |
Mechanical memory and dosing influence stem cell fate
Mechanical cues from the local cellular microenvironment can direct cell fate. Now, experiments with human mesenchymal stem cells cultured on phototunable soft poly(ethylene glycol) hydrogels show that the cells remember past physical environments—with the transcriptional co-activators YAP and TAZ acting as a mechanical rheostat—and therefore that appropriate doses of mechanical cues can be used to manipulate the cells’ fate.
- Chun Yang
- , Mark W. Tibbitt
- & Kristi S. Anseth
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Article |
Galvanotactic control of collective cell migration in epithelial monolayers
The collective migration of epithelial cells arises from the interplay between intercellular forces and cellular signalling networks. It is now shown that the migration of an epithelium can be controlled by applying electric fields that bias the signalling networks, and that such galvanotactic control can prompt cell populations to make coordinated U-turns, undergo divergent or convergent migration, or move against an obstacle.
- Daniel J. Cohen
- , W. James Nelson
- & Michel M. Maharbiz
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Progress Article |
Charge-extraction strategies for colloidal quantum dot photovoltaics
Solar cells based on colloidal quantum dots require specific charge-extraction strategies that take full advantage of the size-tunable absorption properties of the nanoparticles. This Progress Article reviews the recent engineering efforts aimed at maximizing the power-conversion efficiency of these devices by developing novel architectures as well as by optimizing the morphological and electronic properties of both the electrodes and quantum dot layers.
- Xinzheng Lan
- , Silvia Masala
- & Edward H. Sargent
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Progress Article |
Spin-torque building blocks
Memory devices based on the spin-transfer-torque effect offer a range of attractive properties, such as speed of operation and low energy cost. This Progress Article outlines a strategy for assembling different nanodevices based on the spin-torque effect to achieve qualitatively different computing architectures.
- N. Locatelli
- , V. Cros
- & J. Grollier
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Article |
Epithelial bridges maintain tissue integrity during collective cell migration
In wound healing, skin cells collectively migrate to maintain tissue cohesion despite the existence of inhomogeneities in the extracellular environment within the wound bed. Yet how the cell collective responds to heterogeneities in the extracellular matrix is not well understood. Now, it is shown that migrating human keratinocyte cell sheets form suspended multicellular bridges over non-adhesive regions on micropatterned substrates comprising alternating strips of fibronectin and non-adherent polymer.
- Sri Ram Krishna Vedula
- , Hiroaki Hirata
- & Benoit Ladoux
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Review Article |
Engineering synthetic vaccines using cues from natural immunity
The clinical application of vaccines has expanded from infectious diseases to cancer, enhancing our vision of how the immune system can be used to prevent and treat disease. This Review highlights recent developments, clinical successes and future challenges in the design of prophylactic, therapeutic and tolerance-inducing synthetic vaccines with inspiration from the natural immune system.
- Darrell J. Irvine
- , Melody A. Swartz
- & Gregory L. Szeto
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Review Article |
Macroscale delivery systems for molecular and cellular payloads
The use of macroscopic depots to deliver drugs — including small molecules, protein and cells — at the desired treatment site by using a carrier whose physical and chemical properties control the presentation of the drug increases drug effectiveness and reduces side effects. This Review discusses the advantages of macroscopic drug-delivery systems, the associated mechanisms of spatiotemporal control of drug presentation, and the design and use of multifunctional macroscopic drug-delivery devices.
- Cathal J. Kearney
- & David J. Mooney
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Article |
Biophysical regulation of epigenetic state and cell reprogramming
Somatic cells can be reprogrammed into induced pluripotent stem cells biochemically through the expression of a few transcription factors. It is now shown that aligned microgrooves or nanofibres on cell-adhesive substrates can promote the reprogramming of somatic cells more efficiently through epigenetic regulation of genes related to pluripotency and the mesenchymal-to-epithelial transition. The findings suggest that the epigenetic state can be regulated by variations in cell morphology.
- Timothy L. Downing
- , Jennifer Soto
- & Song Li
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Commentary |
Greece in crisis
In spite of substantial progress over the past 35 years, underfunding and lack of evaluation are preventing Greek research and technology from reaching its true potential. A coordinated effort between government, academia and industry could lead to viable solutions to the current crisis.
- Costas M. Soukoulis
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Article |
Propulsion and navigation within the advancing monolayer sheet
Although the collective cellular motion involved in, for example, wound healing and tumour invasion is suspected to be driven by mechanical stresses within the advancing cell monolayer, how motion and stress relate has remained elusive. Now, stress-microscopy observations of an epithelial cell sheet advancing towards a region where cells cannot adhere reveal that the cells located nearby such a region exert forces that pull them towards the unfilled space, regardless of whether the cells approach or recede from it.
- Jae Hun Kim
- , Xavier Serra-Picamal
- & Jeffrey J. Fredberg
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Letter |
Digitally tunable physicochemical coding of material composition and topography in continuous microfibres
The fabrication of composite microfibres with tunable topography and chemical composition is now possible with a microfluidic method that mimics the fibre-spinning process of spiders. The method allows for the synthesis of a variety of structurally and spatially coded fibres for multiple applications, such as directional water harvesting and the co-culture of encapsulated cells.
- Edward Kang
- , Gi Seok Jeong
- & Sang-Hoon Lee
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Letter |
Epitaxial growth of three-dimensionally architectured optoelectronic devices
Three-dimensional photonic devices are of interest as light emitters, detectors or waveguides. However, so far their fabrication has remained a challenge. The template-directed epitaxy of three-dimensional semiconductor structures now offers a new strategy for the realization of photonic devices, demonstrated by the realization of a three-dimensional photonic crystal light-emitting diode.
- Erik C. Nelson
- , Neville L. Dias
- & Paul V. Braun
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News & Views |
Diamonds are forever — or are they?
The friction and wear of materials is part of our everyday experience, and yet these processes are not well understood. The example of diamond highlights wear processes that result from bumping atoms, showing that the devil is indeed in the details.
- Jay Fineberg