Hexagonal Hybrid Bismuthene by Molecular Interface Engineering

High-quality devices based on layered heterostructures are typically built from materials obtained by complex solid-state physical approaches or laborious mechanical exfoliation and transfer. Meanwhile, wet-chemically synthesized materials commonly suffer from surface residuals and intrinsic defects. Here, we synthesize using an unprecedented colloidal photocatalyzed, one-pot redox reaction a few-layers bismuth hybrid of “electronic grade” structural quality. Intriguingly, the material presents a sulfur-alkyl-functionalized reconstructed surface that prevents it from oxidation and leads to a tuned electronic structure that results from the altered arrangement of the surface. The metallic behavior of the hybrid is supported by ab initio predictions and room temperature transport measurements of individual nanoflakes. Our findings indicate how surface reconstructions in two-dimensional (2D) systems can promote unexpected properties that can pave the way to new functionalities and devices. Moreover, this scalable synthetic process opens new avenues for applications in plasmonics or electronic (and spintronic) device fabrication. Beyond electronics, this 2D hybrid material may be of interest in organic catalysis, biomedicine, or energy storage and conversion

Interaction between acrylic substrates and RAD16-I peptide in its self-assembling

[EN] Self-assembling peptides (SAP) are widely used as scaffolds themselves, and recently as fillers of microporous scaffolds, where the former provides a cell-friendly nanoenvironment and the latter improves its mechanical properties. The characterization of the interaction between these short peptides and the scaffold material is crucial to assess the potential of such a combined system. In this work, the interaction between poly(ethyl acrylate) (PEA) and 90/10 ethyl acrylate-acrylic acid copolymer P(EAcoAAc) with the SAP RAD16-I has been followed using a bidimensional simplified model. By means of the techniques of choice (congo red staining, atomic force microscopy (AFM), and contact angle measurements) the interaction and self-assembly of the peptide has proven to be very sensitive to the wettability and electro-negativity of the polymeric substrate.The authors acknowledge funding through the European Commission FP7 project RECATABI (NMP3-SL-2009-229239), and from the Spanish Ministerio de Ciencia e Innovacion through projects MAT2011-28791-C03-02 and -03. This work was also supported by the Spanish Ministerio de Educacion through M. Arnal-Pastor FPU 2009-1870 grant. The authors acknowledge the assistance and advice of Electron Microscopy Service of the UPV.Arnal Pastor, MP.; González-Mora, D.; García-Torres, F.; Monleón Pradas, M.; Vallés Lluch, A. (2016). Interaction between acrylic substrates and RAD16-I peptide in its self-assembling. 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Fibronectin distribution on demixed nanoscale topographies

PURPOSE: It is known that surface nanotopography influences cell adhesion and differentiation. Our aim is to analyze the effect of nanoscale topography on fibronectin adsorption and, afterwards, on cell adhesion in order to rationalize the cell-material interaction by focusing on the state of the intermediate layer of adsorbed fibronectin at the material interphase. METHODS: Nanotopographic surfaces were produced by demixing of thin film polymer blends - PLLA and PS - during a high speed spin-casting process. Fibronectin (FN) was adsorbed on the different nanotopographies and the protein distribution was directly observed by atomic force microscopy (AFM). The fraction of the surface covered by the protein was quantified by image analysis, as well as the distribution of FN between peaks and valleys. Focal adhesion protein -vinculin- was immunostained and quantified by image analysis on the different nanoscale surfaces. RESULTS: Different nanoscale domains were obtained by changing the composition of the system within a height range of 3 nm to 30 nm. FN tends to adsorb on the peaks of nanoisland topographies, especially in compositions that did not enhance cell adhesion. Moreover, protein distribution between valleys and peaks alters the size of focal adhesion plaques, which grew larger on surfaces with an even distribution of fibronectin. CONCLUSIONS: Our results suggest that the surface nanotopography is a key material property capable of influencing protein adsorption. Additionally, the distribution of the protein on the different samples was correlated to the initial ability of cells to adhere in terms of the size of the focal plaques

Regioirregular and catalytic Mizoroki–Heck reactions

The palladium-catalysed cross-coupling reaction between alkenes and aryl halides (the Mizoroki–Heck reaction) is a powerful methodology to construct new carbon–carbon bonds. However, the success of this reaction is in part hampered by an extremely marked regioselectivity on the double bond, which dictates that electron-poor alkenes react exclusively on the β-carbon. Here, we show that ligand-free, few-atom palladium clusters in solution catalyse the α-selective intramolecular Mizoroki–Heck coupling of iodoaryl cinnamates, and mechanistic studies support the formation of a sterically encumbered cinnamate–palladium cluster intermediate. Following this rationale, the α-selective intermolecular coupling of aryl iodides with styrenes is also achieved with palladium clusters encapsulated within fine-tuned and sterically restricted zeolite cavities to produce 1,1-bisarylethylenes, which are further engaged with aryl halides by a metal-free photoredox-catalysed coupling. These ligand-free methodologies significantly expand the chemical space of the Mizoroki–Heck coupling. [Figure not available: see fulltext.]This work was supported by MINECO (Spain, projects CTQ 2017-86735-P, PID2019-105391GB-C22 and MAT2017-82288-C2-1-P, Severo Ochoa programme SEV-2016-0683 and the Juan de la Cierva programme). F.G.-P. and R.G. thank ITQ for the concession of a contract. J.O.-M. acknowledges the Juan de la Cierva programme for the concession of a contract, and R.P.-R. and J.C.-S. thank the Plan GenT programme (CIDEGENT/2018/044) funded by Generalitat Valenciana. HR STEM measurements were performed at DME-UCA in Cadiz University, with financial support from FEDER/MINECO (PID2019-110018GA-I00 and PID2019-107578GA-I00). We acknowledge ALBA Synchrotron for allocating beamtime and CLÆSS beamline staff for their technical support during our experiment.Peer reviewe