Search

Clathrin-mediated endocytosis is a paradigm of a cellular processes that is orchestrated by phosphoinositides, where the plasma membrane phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) plays an instrumental role in the formation of clathrin-coated structures. Among the early endocytic proteins that reach at the plasma membrane, the F-BAR domain only protein 1 and 2 complex (FCHo1/2) is thought to orchestrate the early stages but, the exact mechanism triggering its nucleation on membranes is not well understood. By combining bottom-up synthetic approaches on in vitro and cellular membranes, we show the molecular dynamics of FCHo2 self-assembly on membranes. Our results indicate that PI(4,5)P2 guide the recruitment of FCHo2 at specific regions of the membrane, where it self-assembles into ring-like shape protein patches flanked by membrane invaginations. Importantly, we show that binding of FCHo2 on cellular membranes promotes the enrichment of PI(4,5)P2 at the boundary of specific cargo receptors, such as the epidermal growth factor receptor (EGFR). Thus, our results provide a mechanistic framework that could explain the orchestration of early PI(4,5)P2-interacting proteins recruitment at endocytic sites.

The monolithic integration of sub-micron quartz structures on silicon substrates is a key issue for the future development of piezoelectric devices as prospective sensors with applications based on the operation in the high-frequency range. However, to date, it has not been possible to make existing quartz manufacturing methods compatible with integration on silicon and structuration by top-down lithographic techniques. Here, we report an unprecedented large-scale fabrication of ordered arrays of piezoelectric epitaxial quartz nanostructures on silicon substrates by the combination of soft-chemistry and three lithographic techniques: (i) laser interference lithography, (ii) soft nanoimprint lithography on Sr-doped SiO2 sol–gel thin films, and (iii) self-assembled SrCO3 nanoparticle reactive nanomasks. Epitaxial α-quartz nanopillars with different diameters (from 1 μm down to 50 nm) and heights (up to 2 μm) were obtained. This work demonstrates the complementarity of soft-chemistry and top-down lithographic techniques for the patterning of epitaxial quartz thin films on silicon while preserving its epitaxial crystallinity and piezoelectric properties. These results open up the opportunity to develop a cost-effective on-chip integration of nanostructured piezoelectric α-quartz MEMS with enhanced sensing properties of relevance in different fields of application., This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program, project SENSiSOFT (no. 803004); the French Agence Nationale pour la Recherche (ANR), project Q-NOSS ANR ANR-16-CE09-0006-01; the Spanish Ministry of Science Innovation and Universities in cofunding with European social funds through the Severo Ochoa Program for Centers of Excellence in R&D (SEV-2015-0496) and the Ramón y Cajal program (RyC-2012-11709 to J.G.); and the Generalitat de Catalunya (2017SGR00765). Q.Z. was financially supported by the China Scholarship Council (CSC) with no. 201506060170. Q.Z.’s work was done as a part of the PhD program in Materials Science at Universitat Autònoma de Barcelona. The authors thank the “Laboratorio de Microscopías Avanzadas-Instituto de Nanociencia de Aragón” for offering their expertise in the preparation of TEM cross sections. A. Crespi from XRD diffraction service is acknowledged for pole figure measurements. FEG-SEM instrumentation was facilitated by the Institut des Matériaux de Paris Centre (IMPC FR2482) and was funded by Sorbonne Université, CNRS and by the C’Nano projects of the Région Ile-de-France. We thank David Montero for performing the FEG-SEM images.

International audience; Membrane shape is a key feature of many cellular processes, including cell differentiation, division, migration, and trafficking. The development of nanostructured surfaces allowing for the in situ manipulation of membranes in living cells is crucial to understand these processes, but this requires complicated and limited-access technologies. Here, we investigate the self-organization of cellular membranes by using a customizable and benchtop method allowing one to engineer 1D SiO2 nanopillar arrays of defined sizes and shapes on high-performance glass compatible with advanced microscopies. As a result of this original combination, we provide a mapping of the morphology-induced modulation of the cell membrane mechanics, dynamics and steady-state organization of key protein complexes implicated in cellular trafficking and signal transduction.

Membrane shape is a key feature of many cellular processes, including cell differentiation, division, migration, and trafficking. The development of nanostructured surfaces allowing for the in situ manipulation of membranes in living cells is crucial to understand these processes, but this requires complicated and limited-access technologies. Here, we investigate the self-organization of cellular membranes by using a customizable and bench top method allowing to engineer 1D SiO2 nanopillar arrays of defined sizes and shapes on high-performance glass compatible with advanced microscopies. As a result of this original combination, we provide a mapping of the morphology-induced modulation of the cell membrane mechanics, dynamics and steady-state organization of key protein complexes implicated in cellular trafficking and signal transduction.

The development of advanced piezoelectric α‐quartz microelectromechanical system (MEMS) for sensing and precise frequency control applications requires the nanostructuration and on‐chip integration of this material on silicon material. However, the current quartz manufacturing methods are based on bonding bulk micromachined crystals on silicon, which limits the size, the performance, the integration cost, and the scalability of quartz microdevices. Here, chemical solution deposition, soft‐nanoimprint lithography, and top‐down microfabrication processes are combined to develop the first nanostructured epitaxial (100)α‐quartz/(100)Si piezoelectric cantilevers. The coherent Si/quartz interface and film thinness combined with a controlled nanostructuration on silicon–insulator–silicon technology substrates provide high force and mass sensitivity while preserving the mechanical quality factor of the microelectromechanical systems. This work proves that biocompatible nanostructured epitaxial piezoelectric α‐quartz‐based MEMS on silicon can be engineered at low cost by combining soft‐chemistry and top‐down lithographic techniques., This project had received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (project SENSiSOFT No.803004). L.P. acknowledges the ATIP–Avenir program for financial support. The authors thank C. André for providing the transfected HT1080 cell line and C. Cazevielle (MRI‐COMET, Montpellier) for assistance with biological SEM images. The authors thank D. Montero for performing the FEG–SEM images and chemical analysis. The FEG–SEM instrumentation was facilitated by the Institut des Matériaux de Paris Centre (Grant No. IMPC FR2482) and was funded by Sorbonne Université, CNRS and by the C'Nano projects of the Région Ile‐de‐France. The authors thank Frederic Pichot, David Bourrier, and Guilhem Larrieu for the expertise and advice during the cantilever lithographic processes. The authors also thank Wioletta Trzpil, Frank Augereau, and Eric Rosenkrantz for the advice during vibrometry measurements. A.G and M.G acknowledge funding from the Spanish Ministerio de Ciencia e Innovacion through the severo Ochoa program (CEX2019‐000917‐S).

In this work, we show a detailed engineering route of the first piezoelectric nanostructured epitaxial quartz-based microcantilever. We will explain all the steps in the process starting from the material to the device fabrication. The epitaxial growth of α-quartz film on SOI (100) substrate starts with the preparation of a strontium doped silica sol-gel and continues with the deposition of this gel into the SOI substrate in a thin film form using the dip-coating technique under atmospheric conditions at room temperature. Before crystallization of the gel film, nanostructuration is performed onto the film surface by nanoimprint lithography (NIL). Epitaxial film growth is reached at 1000 °C, inducing a perfect crystallization of the patterned gel film. Fabrication of quartz crystal cantilever devices is a four-step process based on microfabrication techniques. The process starts with shaping the quartz surface, and then metal deposition for electrodes follows it. After removing the silicone, the cantilever is released from SOI substrate eliminating SiO2 between silicon and quartz. The device performance is analyzed by non-contact laser vibrometer (LDV) and atomic force microscopy (AFM). Among the different cantilever's dimensions included in the fabricated chip, the nanostructured cantilever analyzed in this work exhibited a dimension of 40 µm large and 100 µm long and was fabricated with a 600 nm thick patterned quartz layer (nanopillar diameter and separation distance of 400 nm and 1 µm, respectively) epitaxially grown on a 2 µm thick Si device layer. The measured resonance frequency was 267 kHz and the estimated quality factor, Q, of the whole mechanical structure was Q ~ 398 under low vacuum conditions. We observed the voltage-dependent linear displacement of cantilever with both techniques (i.e., AFM contact measurement and LDV). Therefore, proving that these devices can be activated through the indirect piezoelectric effect.