Thermophoresis beyond Local Thermodynamic Equilibrium.

We measure the thermophoresis of polysterene beads over a wide range of temperature gradients and find a pronounced nonlinear phoretic characteristic. The transition to the nonlinear behavior is marked by a drastic slowing down of thermophoretic motion and is characterized by a Péclet number of order unity as corroborated for different particle sizes and salt concentrations. The data follow a single master curve covering the entire nonlinear regime for all system parameters upon proper rescaling of the temperature gradients with the Péclet number.

Ionic Accumulation as a Diagnostic Tool in Perovskite Solar Cells: Characterizing Band Alignment with Rapid Voltage Pulses.

Despite record-breaking devices, interfaces in perovskite solar cells are still poorly understood, inhibiting further progress. Their mixed ionic-electronic nature results in compositional variations at the interfaces, depending on the history of externally applied biases. This makes it difficult to measure the band energy alignment of charge extraction layers accurately.

Lattice Reconstruction in MoSe-WSe Heterobilayers Synthesized by Chemical Vapor Deposition.

Vertical van der Waals heterostructures of semiconducting transition metal dichalcogenides realize moiré systems with rich correlated electron phases and moiré exciton phenomena. For material combinations with small lattice mismatch and twist angles as in MoSe-WSe, however, lattice reconstruction eliminates the canonical moiré pattern and instead gives rise to arrays of periodically reconstructed nanoscale domains and mesoscopically extended areas of one atomic registry. Here, we elucidate the role of atomic reconstruction in MoSe-WSe heterostructures synthesized by chemical vapor deposition.

Building Blocks and COFs Formed in Concert-Three-Component Synthesis of Pyrene-Fused Azaacene Covalent Organic Framework in the Bulk and as Films.

A three-component synthesis methodology is described for the formation of covalent organic frameworks (COFs) containing extended aromatics. Notably, this approach enables synthesis of the building blocks and COF along parallel reaction landscapes, on a similar timeframe. The use of fragmental building block components, namely pyrene dione diboronic acid as aggregation-inducing COF precursor and the diamines o-phenylenediamine (Ph), 2,3-diaminonaphthalene (Naph), or (1R,2R)-(+)-1,2-diphenylethylenediamine (2Ph) as extending functionalization units in conjunction with 2,3,6,7,10,11-hexahydroxytriphenylene, resulted in the formation of the corresponding pyrene-fused azaacene, i.

Electrically Conductive Carbazole and Thienoisoindigo-Based COFs Showing Fast and Stable Electrochromism.

Thienothiophene thienoisoindigo (ttTII)-based covalent organic frameworks (COFs) have been shown to offer low band gaps and intriguing optical and electrochromic properties. So far, only one tetragonal thienothiophene thienoisoindigo-based COF has been reported showing stable and fast electrochromism and good coloration efficiencies. We have developed two novel COFs using this versatile and nearly linear ttTII building block in a tetragonal and a hexagonal framework geometry to demonstrate their attractive features for optoelectronic applications of thienoisoindigo-based COFs.

Lead-Free, Luminescent Perovskite Nanocrystals Obtained through Ambient Condition Synthesis.

Heterovalently substituting toxic lead is an increasingly popular design strategy to obtain environmentally sustainable variants of the exciting material class of halide perovskites. Perovskite nanocrystals (NCs) obtained through solution-based methods exhibit exceedingly high optical quality. Unfortunately, most of these synthesis routes still require reaction under inert gas and at very high temperatures.

Mosquito bite prevention through self-assembled cellulose nanocrystals.

Mosquitoes are the deadliest of all combined insects and animals affecting millions and killing hundreds or thousands of people each year. Existing protection methods however are limited and include volatile compounds that actively repel mosquitoes such as N,N-Diethyl-meta-toluamide (DEET) or different essential oils such as geraniol and citronella. Most are odorous compounds and require organic solvents for dispersion.

Enzyme-Enriched Condensates Show Self-Propulsion, Positioning, and Coexistence.

Enzyme-enriched condensates can organize the spatial distribution of their substrates by catalyzing nonequilibrium reactions. Conversely, an inhomogeneous substrate distribution induces enzyme fluxes through substrate-enzyme interactions. We find that condensates move toward the center of a confining domain when this feedback is weak.

The selection of a hydrophobic 7-phenylbutyl-7-deazaadenine-modified DNA aptamer with high binding affinity for the Heat Shock Protein 70.

Nucleic acids aptamers often fail to efficiently target some proteins because of the hydrophilic character of the natural nucleotides. Here we present hydrophobic 7-phenylbutyl-7-deaadenine-modified DNA aptamers against the Heat Shock Protein 70 that were selected via PEX and magnetic bead-based SELEX. After 9 rounds of selection, the pool was sequenced and a number of candidates were identified.

Ultrafast hot electron-hole plasma photoluminescence in two-dimensional semiconductors.

The transition metal dichalcogenide family of semiconducting two-dimensional materials has recently shown a prominent potential to be an ideal platform to study the exciton Mott transition into electron-hole plasma and liquid phases due to their strong Coulomb interactions. Here, we show that pulsed laser excitation at high pump fluences can induce this exciton Mott transition to an electron-hole plasma in mono and few-layer transition metal dichalcogenides at room temperature. The formation of an electron-hole plasma leads to a broadband light emission spanning from the near infrared to the visible region.

Origin of the spectral red-shift and polarization patterns of self-assembled InGaN nanostructures on GaN nanowires.

The luminescence of InGaN nanowires (NWs) is frequently reported with large red-shifts as compared to the theoretical value expected from the average In content. Both compositional fluctuations and radial built-in fields were considered accountable for this effect, depending on the size, structure, composition, and surrounding medium of the NWs. In the present work, the emission properties of InGaN/GaN NWs grown by plasma-assisted molecular beam epitaxy are investigated in a comprehensive study combining ultraviolet-Raman and photoluminescence spectroscopy (PL) on vertical arrays, polarization-dependent PL on bundles of a few NWs, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, and calculations of the band profiles.

Nitric Oxide (NO) as a Reagent for Topochemical Framework Transformation and Controlled NO Release in Covalent Organic Frameworks.

Covalent organic frameworks (COFs) have emerged as versatile platforms for the separation and storage of hazardous gases. Simultaneously, the synthetic toolbox to tackle the "COF trilemma" has been diversified to include topochemical linkage transformations and post-synthetic stabilization strategies. Herein, we converge these themes and reveal the unique potential of nitric oxide (NO) as a new reagent for the scalable gas-phase transformation of COFs.

Excitons in mesoscopically reconstructed moiré heterostructures.

Moiré effects in vertical stacks of two-dimensional crystals give rise to new quantum materials with rich transport and optical phenomena that originate from modulations of atomic registries within moiré supercells. Due to finite elasticity, however, the superlattices can transform from moiré-type to periodically reconstructed patterns. Here we expand the notion of such nanoscale lattice reconstruction to the mesoscopic scale of laterally extended samples and demonstrate rich consequences in optical studies of excitons in MoSe-WSe heterostructures with parallel and antiparallel alignments.

Ribozyme-mediated RNA synthesis and replication in a model Hadean microenvironment.

Enzyme-catalyzed replication of nucleic acid sequences is a prerequisite for the survival and evolution of biological entities. Before the advent of protein synthesis, genetic information was most likely stored in and replicated by RNA. However, experimental systems for sustained RNA-dependent RNA-replication are difficult to realise, in part due to the high thermodynamic stability of duplex products and the low chemical stability of catalytic RNAs.

Full Site-Specific Addressability in DNA Origami-Templated Silica Nanostructures.

DNA nanotechnology allows for the fabrication of nanometer-sized objects with high precision and selective addressability as a result of the programmable hybridization of complementary DNA strands. Such structures can template the formation of other materials, including metals and complex silica nanostructures, where the silica shell simultaneously acts to protect the DNA from external detrimental factors. However, the formation of silica nanostructures with site-specific addressability has thus far not been explored.

Combining pMINFLUX, graphene energy transfer and DNA-PAINT for nanometer precise 3D super-resolution microscopy.

3D super-resolution microscopy with nanometric resolution is a key to fully complement ultrastructural techniques with fluorescence imaging. Here, we achieve 3D super-resolution by combining the 2D localization of pMINFLUX with the axial information of graphene energy transfer (GET) and the single-molecule switching by DNA-PAINT. We demonstrate <2 nm localization precision in all 3 dimension with axial precision reaching below 0.

Optical and Electrochemical Probes for Monitoring Cytochrome c in Subcellular Compartments During Apoptosis.

Cytochrome c (Cyt. c) is a key initiator of the caspases that activate cell apoptosis. The spatiotemporal evaluation of the contents of Cyt.

Photolithographic microfabrication of hydrogel clefts for cell invasion studies.

Invasion of migrating cells into surrounding tissue plays a key role in cancer metastasis and immune response. In order to assess invasiveness, most invasion assays measure the degree to which cells migrate between microchambers that provide a chemoattractant gradient across a polymeric membrane with defined pores. However, in real tissue cells experience soft, mechanically deformable microenvironments.

A new twist on PIFE: photoisomerisation-related fluorescence enhancement.

PIFE was first used as an acronym for protein-induced fluorescence enhancement, which refers to the increase in fluorescence observed upon the interaction of a fluorophore, such as a cyanine, with a protein. This fluorescence enhancement is due to changes in the rate of cis/trans photoisomerisation. It is clear now that this mechanism is generally applicable to interactions with any biomolecule and, in this review, we propose that PIFE is thereby renamed according to its fundamental working principle as photoisomerisation-related fluorescence enhancement, keeping the PIFE acronym intact.

Antigen footprint governs activation of the B cell receptor.

Antigen binding by B cell receptors (BCR) on cognate B cells elicits a response that eventually leads to production of antibodies. However, it is unclear what the distribution of BCRs is on the naïve B cell and how antigen binding triggers the first step in BCR signaling. Using DNA-PAINT super-resolution microscopy, we find that most BCRs are present as monomers, dimers, or loosely associated clusters on resting B cells, with a nearest-neighbor inter-Fab distance of 20-30 nm.

A label-free light-scattering method to resolve assembly and disassembly of DNA nanostructures.

DNA self-assembly, and in particular DNA origami, has evolved into a reliable workhorse for organizing organic and inorganic materials with nanometer precision and with exactly controlled stoichiometry. To ensure the intended performance of a given DNA structure, it is beneficial to determine its folding temperature, which in turn yields the best possible assembly of all DNA strands. Here, we show that temperature-controlled sample holders and standard fluorescence spectrometers or dynamic light-scattering setups in a static light-scattering configuration allow for monitoring the assembly progress in real time.

Optical Activity and Spin Polarization: The Surface Effect.

Chirality ('handedness') is a property that underlies a broad variety of phenomena in nature. Chiral molecules appear in two forms, and each is a mirror image of the other, the two enantiomers. The chirality of molecules is associated with their optical activity, and circular dichroism is commonly applied to identify the handedness of chiral molecules.

DNA Origami Fiducial for Accurate 3D Atomic Force Microscopy Imaging.

Atomic force microscopy (AFM) is a powerful technique for imaging molecules, macromolecular complexes, and nanoparticles with nanometer resolution. However, AFM images are distorted by the shape of the tip used. These distortions can be corrected if the tip shape can be determined by scanning a sample with features sharper than the tip and higher than the object of interest.

Rich Landscape of Colloidal Semiconductor-Metal Hybrid Nanostructures: Synthesis, Synergetic Characteristics, and Emerging Applications.

Nanochemistry provides powerful synthetic tools allowing one to combine different materials on a single nanostructure, thus unfolding numerous possibilities to tailor their properties toward diverse functionalities. Herein, we review the progress in the field of semiconductor-metal hybrid nanoparticles (HNPs) focusing on metal-chalcogenides-metal combined systems. The fundamental principles of their synthesis are discussed, leading to a myriad of possible hybrid architectures including Janus zero-dimensional quantum dot-based systems and anisotropic quasi 1D nanorods and quasi-2D platelets.

DNA Origami Curvature Sensors for Nanoparticle and Vesicle Size Determination with Single-Molecule FRET Readout.

Particle size is an important characteristic of materials with a direct effect on their physicochemical features. Besides nanoparticles, particle size and surface curvature are particularly important in the world of lipids and cellular membranes as the cell membrane undergoes conformational changes in many biological processes which leads to diverging local curvature values. On account of that, it is important to develop cost-effective, rapid and sufficiently precise systems that can measure the surface curvature on the nanoscale that can be translated to size for spherical particles.