Exfoliation of lamellar materials into their corresponding layers represented a breakthrough, due to the outstanding properties arising from the nanometric thickness confinement. Among the cleavage techniques, liquid-phase exfoliation is now on the rise because it is scalable and leads to easy-to-manipulate colloids. However, all appropriate exfoliating solvents exhibit strong polarity, which restrains a lot the scope of feasible functionalization or processing of the resulting flakes. Here we propose to extend this scope, demonstrating that nanosheets exfoliated in a polar medium can be properly dispersed in a non-polar solvent. To that purpose, we prepared suspensions of molybdenum disulfide flakes in isopropanol/water and developed a phase transfer of the nanosheets to chloroform via precipitation and redispersion/centrifugation sequences, without any assisting surfactant. The colloidal stability of the nanosheets in chloroform was found to be governed by their lateral dimensions and, although lower than in polar media, proved to be high enough to open the way to subsequent functionalization or processing of the flakes in non-polar medium.
The ability of amyloid- peptide (A) to disrupt membrane integrity and cellular homeostasis is believed to be central to Alzheimer's disease pathology. A is reported to have various impacts on the lipid bilayer, but a clearer picture of A influence on membranes is required. Here, we use atomic force and transmission electron microscopies to image the impact of different isolated A assembly types on lipid bilayers. We show that only oligomeric A can profoundly disrupt the bilayer, visualized as widespread lipid extraction and subsequent deposition, which can be likened to an effect expected from the action of a detergent. We further show that A oligomers cause widespread curvature and discontinuities within lipid vesicle membranes. In contrast,thisdetergent-likeeffectwasnotobservedforAmonomers and fibers, although A fibers did laterally associate and embed into the upper leaflet of the bilayer. The marked impact of A oligomers on membrane integrity identified here reveals a mechanism by which these oligomers may be cytotoxic.
We investigate in detail the optical, electrochemical, structural and electrical properties of polythiophenes with increasing content of polar side chains.
A series of semiconducting small molecules with bithiophene or bis‐3,4‐ethylenedioxythiophene cores are designed and synthesized. The molecules display stable reversible oxidation in solution and can be reversibly oxidized in the solid state with aqueous electrolyte when functionalized with polar triethylene glycol side chains. Evidence of promising ion injection properties observed with cyclic voltammetry is complemented by strong electrochromism probed by spectroelectrochemistry. Blending these molecules with high molecular weight polyethylene oxide (PEO) is found to improve both ion injection and thin film stability. The molecules and their corresponding PEO blends are investigated as active layers in organic electrochemical transistors (OECTs). For the most promising molecule:polymer blend (P4E4:PEO), p‐type accumulation mode OECTs with µA drain currents, μS peak transconductances, and a µC* figure‐of‐merit value of 0.81 F V−1 cm−1 s−1 are obtained.
We report the site-specific coupling of single proteins to individual carbon nanotubes (CNTs) in solution and with single-molecule control. Using an orthogonal Click reaction, Green Fluorescent Protein (GFP) was engineered to contain a genetically encoded azide group and then bound to CNT ends in different configurations: in close proximity or at longer distances from the GFP's functional center. Atomic force microscopy and fluorescence analysis in solution and on surfaces at the single-protein level confirmed the importance of bioengineering optimal protein attachment sites to achieve direct protein-nanotube communication and bridging.
Layered two‐dimensional (2D) inorganic transition‐metal dichalchogenides (TMDs) have attracted great interest as a result of their potential application in optoelectronics, catalysis, and medicine. However, methods to functionalize and process such 2D TMDs remain scarce. We have established a facile route towards functionalized layered MoS2. We found that the reaction of liquid‐exfoliated 2D MoS2, with M(OAc)2 salts (M=Ni, Cu, Zn; OAc=acetate) yielded functionalized MoS2–M(OAc)2 materials. Importantly, this method furnished the 2H‐polytype of MoS2 which is a semiconductor. X‐ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT–IR), and thermogravimetric analysis (TGA) provide strong evidence for the coordination of MoS2 surface sulfur atoms to the M(OAc)2 salt. Interestingly, functionalization of 2H‐MoS2 allows for its dispersion/processing in more conventional laboratory solvents.
We present a facile strategy of general applicability for the assembly of individual nanoscale moieties in array configurations with single-molecule control. Combining the programming ability of DNA as a scaffolding material with a one-step lithographic process, we demonstrate the patterning of single quantum dots (QDs) at predefined locations on silicon and transparent glass surfaces: as proof of concept, clusters of either one, two, or three QDs were assembled in highly uniform arrays with a 60 nm interdot spacing within each cluster. Notably, the platform developed is reusable after a simple cleaning process and can be designed to exhibit different geometrical arrangements.
Herein a strategy is presented for the assembly of both static and stimuli‐responsive single‐molecule heterostructures, where the distance and electronic coupling between an individual functional nanomoiety and a carbon nanostructure are tuned via the use of DNA linkers. As proof of concept, the formation of 1:1 nanohybrids is controlled, where single quantum dots (QDs) are tethered to the ends of individual carbon nanotubes (CNTs) in solution with DNA interconnects of different lengths. Photoluminescence investigations—both in solution and at the single‐hybrid level—demonstrate the electronic coupling between the two nanostructures; notably this is observed to progressively scale, with charge transfer becoming the dominant process as the linkers length is reduced. Additionally, stimuli‐responsive CNT‐QD nanohybrids are assembled, where the distance and hence the electronic coupling between an individual CNT and a single QD are dynamically modulated via the addition and removal of potassium (K+) cations; the system is further found to be sensitive to K+ concentrations from 1 pM to 25 × 10−3
m. The level of control demonstrated here in modulating the electronic coupling of reconfigurable single‐molecule heterostructures, comprising an individual functional nanomoiety and a carbon nanoelectrode, is of importance for the development of tunable molecular optoelectronic systems and devices.
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