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We present single molecule studies demonstrating the capabilities of the FRET-PAINT method to detect secondary structures that would be challenging to detect with alternative methods, particularly single molecule FRET (smFRET). Instead of relying on the change in end-to-end separation as in smFRET, we use the change in accessibility to a small probe as the criterion for secondary structure formation and relative stability. As a model system, we study G-triplex formation by human telomeric repeat sequences in different structural contexts. [ABSTRACT FROM AUTHOR]

Cancer stem cells drive disease progression and relapse in many types of cancer. Despite this, a thorough characterization of these cells remains elusive and with it the ability to eradicate cancer at its source. In acute myeloid leukemia (AML), leukemic stem cells (LSCs) underlie mortality but are difficult to isolate due to their low abundance and high similarity to healthy hematopoietic stem cells (HSCs). Here, we demonstrate that LSCs, HSCs, and pre-leukemic stem cells can be identified and molecularly profiled by combining single-cell transcriptomics with lineage tracing using both nuclear and mitochondrial somatic variants. While mutational status discriminates between healthy and cancerous cells, gene expression distinguishes stem cells and progenitor cell populations. Our approach enables the identification of LSC-specific gene expression programs and the characterization of differentiation blocks induced by leukemic mutations. Taken together, we demonstrate the power of single-cell multi-omic approaches in characterizing cancer stem cells. Leukaemic stem cells drive acute myeloid leukaemia (AML) progression and relapse but they are incompletely characterized. Here, the authors combine single-cell transcriptomics and clonal tracking using nuclear and mitochondrial somatic variants to distinguish healthy, pre-leukaemic and leukaemic stem cells in AML. [ABSTRACT FROM AUTHOR]

A flow‐focusing microfluidic device is used to produce functionalized monodisperse polymer particles with surface chemistries designed to control bacterial biofilm formation. This is achieved by using molecularly designed bespoke surfactants synthesized via catalytic chain transfer polymerization. This novel approach of using polymeric surfactants, often called surfmers, containing a biofunctional moiety contrasts with the more commonly employed emulsion methods. Typically, the surface chemistry of microparticles are dominated by unwanted surfactants that dilute/mask the desired surface response. Time of flight secondary ion mass spectrometry (ToF‐SIMS) analysis of particles demonstrates that the comb‐graft surfactant is located on the particle surface. Biofilm experiments show how specifically engineered surface chemistries, generated by the surfactants, successfully modulate bacterial attachment to both polymer films, and microparticles. Thus, this paper outlines how the use of designed polymeric surfactants and droplet microfluidics can exert control over both the surface chemistry and size distribution of microparticle materials, demonstrating their critical importance for controlling surface‐cell response. [ABSTRACT FROM AUTHOR]

We investigate ambipolar charge transport in organic field-effect transistors (OFETs) with copper-phthalocyanine (CuPc) as active material. It is shown that charge carrier mobilities can be increased by at least one order of magnitude using the long-chain alkane tetratetracontane (TTC) as a passivation layer on top of silicon dioxide. TTC and CuPc films are characterized by atomic force microscopy and x-ray diffraction. TTC forms a highly crystalline layer that passivates electron traps on the SiO2 surface very efficiently and serves as a template for the growth of CuPc films with significantly improved crystallinity. High electron mobilities comparable to the values reported on single crystals are reached. We show that the contact resistance for hole transport as determined by the transmission line method can be reduced considerably by using organic charge-transfer complexes as top contacts in OFETs based on CuPc. [ABSTRACT FROM AUTHOR]

The acquisition of mesenchymal traits is considered a hallmark of breast cancer progression. However, the functional relevance of epithelial-to-mesenchymal transition (EMT) remains controversial and context dependent. Here, we isolate epithelial and mesenchymal populations from human breast cancer metastatic biopsies and assess their functional potential in vivo. Strikingly, progressively decreasing epithelial cell adhesion molecule (EPCAM) levels correlate with declining disease propagation. Mechanistically, we find that persistent EPCAM expression marks epithelial clones that resist EMT induction and propagate competitively. In contrast, loss of EPCAM defines clones arrested in a mesenchymal state, with concomitant suppression of tumorigenicity and metastatic potential. This dichotomy results from distinct clonal trajectories impacting global epigenetic programs that are determined by the interplay between human ZEB1 and its target GRHL2. Collectively, our results indicate that susceptibility to irreversible EMT restrains clonal propagation, whereas resistance to mesenchymal reprogramming sustains disease spread in multiple models of human metastatic breast cancer, including patient-derived cells in vivo. [Display omitted] • EPCAM(high) cells from metastatic biopsies can propagate breast cancer in xenografts • Resistance to EMT sustains tumorigenesis and metastatic spread of the human disease • Irreversible EMT results in restrained tumorigenic potential in clonal subsets • ZEB1 and its target GRHL2 control distinct epigenetic paths of EMT susceptibility Saini et al. show that human breast cancer cells resist EMT induction and maintain high EPCAM expression to propagate the metastatic disease. In contrast, loss of EPCAM defines clones arresting in a mesenchymal state with suppressed tumorigenic features. Clonal levels of ZEB1 and GRHL2 control global epigenetic programs determining EMT resistance. [ABSTRACT FROM AUTHOR]

Summary Quiescent long-term hematopoietic stem cells (LT-HSCs) are efficiently activated by type I interferon (IFN-I). However, this effect remains poorly investigated in the context of IFN-I-inducing virus infections. Here we report that both vesicular stomatitis virus (VSV) and murine cytomegalovirus (MCMV) infection induce LT-HSC activation that substantially differs from the effects triggered upon injection of synthetic IFN-I-inducing agents. In both infections, inflammatory responses had to exceed local thresholds within the bone marrow to confer LT-HSC cell cycle entry, and IFN-I receptor triggering was not critical for this activation. After resolution of acute MCMV infection, LT-HSCs returned to phenotypic quiescence. However, non-acute MCMV infection induced a sustained inflammatory milieu within the bone marrow that was associated with long-lasting impairment of LT-HSC function. In conclusion, our results show that systemic virus infections fundamentally affect LT-HSCs and that also non-acute inflammatory stimuli in bone marrow donors can affect the reconstitution potential of bone marrow transplants. [ABSTRACT FROM AUTHOR]

This study reports on the characterization of reporter dye-loaded block copolymer vesicles (polymersomes) of PS115- b-PAA15 (polystyrene-block-poly(acrylic acid)) and PEG114- b-PLA167 (poly(ethylene glycol)-block-poly(lactic acid)) and their drying behavior by fluorescence lifetime imaging microscopy (FLIM). The characteristic changes of the fluorescence decay components of the dye calcein incorporated in the three different local nanoenvironments, namely, the solvated dye, dye associated with the vesicle wall, and dried agglomerated dye, are observed by FLIM during the drying of vesicles. The amplitude ratio R1/2 of the components attributed to the solvated dye in the vesicle interior with a lifetime τ1 ≈ 3.9 ns to the one attributed to calcein associated with the wall with a lifetime τ2 ≈ 1.5 ns is found to decrease exponentially with drying time. The time constants, which are found to depend linearly on the radius of the vesicle, yield by extrapolation to zero vesicle diameter an estimate of the polymersome wall thickness. For PS115- b-PAA15 and PEG114- b-PLA167 vesicle wall thicknesses r0 of 16 ± 5 nm and 28 ± 4 nm, respectively, are observed, which are in favorable agreement with transmission electron and atomic force microscopy data. [ABSTRACT FROM AUTHOR]

Polystyrene- block-poly(acrylic acid) (PS- b-PAA) diblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Self-assembly of these block copolymers into polymeric vesicles, so-called polymersomes, was performed by addition of water to a solution of the block copolymers in tetrahydrofuran (THF). Various antimicrobial compounds and dyes were incorporated in the polymersomes and in addition to the corresponding size distributions, as determined by dynamic light scattering (DLS), the maximum attainable loading concentrations were determined. Using the release of incorporated calcein, which is a pH responsive dye, the principle of a light up probe approach for advanced in situ diagnostics was demonstrated. The release from PS- b-PAA vesicles via a vesicle-to-micelle transition was triggered by heating a vesicle suspension after addition of the plasticizer THF to 50 °C. Furthermore, a biocompatible and degradable block copolymer system, which contains degradable ester bonds in the main chain, was synthesized and investigated. In particular, poly(ethylene glycol)- block-polycaprolactone (PEG- b-PCL) copolymers were synthesized via ring-opening polymerization (ROP). These copolymers were shown to form polymersomes as well and represent a promising family of degradable amphiphilic block copolymers for active wound dressings and related applications. [ABSTRACT FROM AUTHOR]

The use of single crystals has been fundamental to the development of semiconductor microelectronics and solid-state science. Whether based on inorganic or organic materials, the devices that show the highest performance rely on single-crystal interfaces, with their nearly perfect translational symmetry and exceptionally high chemical purity. Attention has recently been focused on developing simple ways of producing electronic devices by means of printing technologies. 'Printed electronics' is being explored for the manufacture of large-area and flexible electronic devices by the patterned application of functional inks containing soluble or dispersed semiconducting materials. However, because of the strong self-organizing tendency of the deposited materials, the production of semiconducting thin films of high crystallinity (indispensable for realizing high carrier mobility) may be incompatible with conventional printing processes. Here we develop a method that combines the technique of antisolvent crystallization with inkjet printing to produce organic semiconducting thin films of high crystallinity. Specifically, we show that mixing fine droplets of an antisolvent and a solution of an active semiconducting component within a confined area on an amorphous substrate can trigger the controlled formation of exceptionally uniform single-crystal or polycrystalline thin films that grow at the liquid-air interfaces. Using this approach, we have printed single crystals of the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) (ref. 15), yielding thin-film transistors with average carrier mobilities as high as 16.4?cm2?V?1?s?1. This printing technique constitutes a major step towards the use of high-performance single-crystal semiconductor devices for large-area and flexible electronics applications. [ABSTRACT FROM AUTHOR]

We fabricated high-performance single crystal organic field-effect transistors (SC-OFETs) based on dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]-thiophene (DNTT). Among various device geometries and contact types, best performance is obtained for a lamination-type SC-OFET composed of a Cytop-treated SiO2 gate dielectric and top-contact gold/tetrathiafulvalene-tetracyanoquinodimethane electrodes, which results in hysteresis-free device characteristics with optimum mobility of 8.3 cm2/V s and an on/off ratio of >108. The achieved performance is promising for use of the air-stable DNTT in future studies of intrinsic properties of molecular crystals. [ABSTRACT FROM AUTHOR]

C60 field-effect transistors (FETs) have been fabricated with parylene gate dielectric on Si/SiO2, on polyethylene terephthalate, and commercially available transparent sheet substrates. The best performance of the C60 FET device is achieved with parylene as gate dielectric: field-effect mobility of 0.41 cm2 V-1 s-1 and on-off ratio of ∼107. The excellent FET characteristics are recorded without any annealing, and the devices were kept in He atmosphere after an exposure to air. This result suggests the parylene gate dielectric to be highly H2O repellent. The mechanical flexibility and air-exposure effect were studied for the C60 FET with parylene gate dielectric. [ABSTRACT FROM AUTHOR]