Annalisa Calò - Academia.edu (original) (raw)

Papers by Annalisa Calò

Scientific Reports

Changes in the elastic properties of living tissues during normal development and in pathological... more Changes in the elastic properties of living tissues during normal development and in pathological processes are often due to modifications of the collagen component of the extracellular matrix at various length scales. Force volume AFM can precisely capture the mechanical properties of biological samples with force sensitivity and spatial resolution. The integration of AFM data with data of the molecular composition contributes to understanding the interplay between tissue biochemistry, organization and function. The detection of micrometer-size, heterogeneous domains at different elastic moduli in tissue sections by AFM has remained elusive so far, due to the lack of correlations with histological, optical and biochemical assessments. In this work, force volume AFM is used to identify collagen-enriched domains, naturally present in human and mouse tissues, by their elastic modulus. Collagen identification is obtained in a robust way and affordable timescales, through an optimal des...

Tumor Progression: Mechano-Signaling and Control

ABSTRACTImmune cells identify cancer cells by recognizing characteristic biochemical features ind... more ABSTRACTImmune cells identify cancer cells by recognizing characteristic biochemical features indicative of oncogenic transformation. Cancer cells have characteristic mechanical features, as well, but whether these biophysical properties also contribute to destruction by the immune system is not known. In the present study, we found that enhanced expression of myocardin related transcription factors (MRTFs), which promote migration and metastatic invasion, paradoxically compromised lung colonization by melanoma and breast carcinoma cells in an immune-mediated manner. Cancer cells with increased MRTF signaling were also more sensitive to immune checkpoint blockade therapy in mice and humans. The basis for this vulnerability was not biochemical, but biophysical. MRTF expression strengthened the actin cytoskeleton, increasing the rigidity of cancer cells and thereby making them more vulnerable to cytotoxic T lymphocytes and natural killer cells. These results reveal a mechanical dimens...

ACS Applied Materials & Interfaces

Communications Physics

Magnonics is gaining momentum as an emerging technology for information processing. The wave char... more Magnonics is gaining momentum as an emerging technology for information processing. The wave character and Joule heating-free propagation of spin-waves hold promises for highly efficient computing platforms, based on integrated magnonic circuits. The realization of such nanoscale circuitry is crucial, although extremely challenging due to the difficulty of tailoring the nanoscopic magnetic properties with conventional approaches. Here we experimentally realize a nanoscale reconfigurable spin-wave circuitry by using patterned spin-textures. By space and time-resolved scanning transmission X-ray microscopy imaging, we directly visualize the channeling and steering of propagating spin-waves in arbitrarily shaped nanomagnonic waveguides, with no need for external magnetic fields or currents. Furthermore, we demonstrate a prototypic circuit based on two converging nanowaveguides, allowing for the tunable spatial superposition and interference of confined spin-waves modes. This work paves the way to the use of engineered spin-textures as building blocks of spin-wave based computing devices.

Nature Electronics

Two-dimensional semiconductors, such as molybdenum disulfide (MoS2), exhibit a variety of propert... more Two-dimensional semiconductors, such as molybdenum disulfide (MoS2), exhibit a variety of properties that could be useful in the development of novel electronic devices. However, nanopatterning metal electrodes on such atomic layers, which is typically achieved using electron beam lithography, is currently problematic, leading to non-ohmic contacts and high Schottky barriers. Here, we show that thermal scanning probe lithography can be used to pattern metal electrodes with high reproducibility, sub-10 nm resolution, and high throughput (10 5 μm 2 /h per single probe). The approach, which offers simultaneous in situ imaging and patterning, does not require a vacuum, high energy, or charged beams, in contrast to electron beam lithography. Using this technique, we pattern metal electrodes in direct contact with monolayer MoS2 for top-gate and back-gate field-effect transistors. These devices exhibit vanishing Schottky barrier heights (around 0 meV), on/off ratios of 10 10 , no hysteresis, and subthreshold swings as low as 64 mV/dec without using negative capacitors or hetero-stacks.

$Research paper thumbnail of {"__content__"=>"Friction and work function oscillatory behavior for an even and odd number of layers in polycrystalline MoS.", "sub"=>{"__content__"=>"2"}}$

Nanoscale, Jan 3, 2018

A large effort is underway to investigate the properties of two-dimensional (2D) materials for th... more A large effort is underway to investigate the properties of two-dimensional (2D) materials for their potential to become building blocks in a variety of integrated nanodevices. In particular, the ability to understand the relationship between friction, adhesion, electric charges and defects in 2D materials is of key importance for their assembly and use in nano-electro-mechanical and energy harvesting systems. Here, we report on a new oscillatory behavior of nanoscopic friction in continuous polycrystalline MoS2 films for an odd and even number of atomic layers, where odd layers show higher friction and lower work function. Friction force microscopy combined with Kelvin probe force microscopy and X-ray photoelectron spectroscopy demonstrates that an enhanced adsorption of charges and OH molecules is at the origin of the observed increase in friction for 1 and 3 polycrystalline MoS2 layers. In polycrystalline films with an odd number of layers, each crystalline nano-grain carries a d...

Scientific reports, Jan 13, 2017

This study aims to improve our understanding of the interaction between olfactory receptors and o... more This study aims to improve our understanding of the interaction between olfactory receptors and odorants to develop highly selective biosensing devices. Natural nanovesicles (NVs) from Saccharomyces cerevisiae, ~100 nm in diameter, carrying either the human OR17-40 or the chimpanzee OR7D4 olfactory receptor (OR) tagged with the c-myc epitope at their N-terminus, are presented as model systems to quantify the interaction between odorant and olfactory receptors. The level of expression of olfactory receptors was determined at individual NVs using a novel competitive ELISA immunoassay comparing the values obtained against those from techniques involving the solubilization of cell membrane proteins and the identification of c-myc-carrying receptors. Surface Plasmon Resonance (SPR) measurements on L1 Biacore chips indicate that cognate odorants bind to their Ors, thereby quantifying the approximate number of odorants that interact with a given olfactory receptor. The selectivity of OR17-...

The Journal of Physical Chemistry C, 2016

Polarization dependence of water adsorption and desorption on LiNbO 3 surfaces was demonstrated u... more Polarization dependence of water adsorption and desorption on LiNbO 3 surfaces was demonstrated using X-ray photoelectron spectroscopy (XPS) carried out in situ under nearambient conditions. Positive and negative (0001) faces (z-cut) of the same crystal were compared for the same temperature and pressure conditions. Our results indicate a preferential adsorption on the positive face of the crystal with increasing water pressure and also higher desorption temperature of the adsorbed molecular water at the positive face. Adsorption measurements on the (1100) face (y-cut) showed also strong affinity to water, as observed for the zcut positive surface. We found a direct relation between the capacity of the surface to discharge and/or to screen surface charges and the affinity for water of each face. XPS spectra indicate the presence of OH groups at the surface for all the conditions and surfaces measured.

Microscopy Research and Technique, 2016

Japanese Journal of Applied Physics, 2016

The Journal of Physical Chemistry C, 2015

ABSTRACT The structure of water films in contact with surfaces has direct implications in many im... more ABSTRACT The structure of water films in contact with surfaces has direct implications in many important interfacial processes, from biology to climatology, as well as in ice nucleation. Here we report on the detection of individual ice-like water layers adsorbed on surfaces in ambient conditions. Reconstructed force profiles obtained in amplitude modulation atomic force microscopy (AM-AFM) on top of (111) BaF2 surfaces, with a lattice constant close to the distance of facing water molecules in hexagonal ice (Ih), showed characteristic oscillations in the attractive regime with a periodicity of 3.7 Å. This distance matches the thickness of a bilayer of Ih ice and is absent in force profiles on (111) CaF2 surfaces, that show a different lattice parameter. A thickness of 2.6 Å is measured for the first water layer in contact with the surface, corresponding to a high-density liquid film structure predicted from calculations in the literature. Our results indicate that, although epitaxial Ih growth of the first water layer on BaF2 crystals is not observed, the matching of the lattice parameter between Ih and BaF2 does induce a strong ordering of the water films and the formation of ice-like structures, even at room temperature.

Beilstein Journal of Nanotechnology, 2015

There has been much interest in the past two decades to produce experimental force profiles chara... more There has been much interest in the past two decades to produce experimental force profiles characteristic of the interaction between nanoscale objects or a nanoscale object and a plane. Arguably, the advent of the atomic force microscope AFM was instrumental in driving such efforts because, in principle, force profiles could be recovered directly. Nevertheless, it has taken years before techniques have developed enough as to recover the attractive part of the force with relatively low noise and without missing information on critical ranges, particularly under ambient conditions where capillary interactions are believed to dominate. Thus a systematic study of the different profiles that may arise in such situations is still lacking. Here we employ the surfaces of CaF2, on which nanoscale water films form, to report on the range and force profiles that might originate by dynamic capillary interactions occurring between an AFM tip and nanoscale water patches. Three types of force pro...

The Journal of Physical Chemistry C, 2011

Review of Scientific Instruments, 2010

We describe a setup suitable for simultaneously measuring optical and electrical properties of a ... more We describe a setup suitable for simultaneously measuring optical and electrical properties of a liquid crystal mesophase upon temperature variation, and the difference in the order parameters between the bulk and the interface with the substrate. It integrates high-resolution polarized light optical microscopy, temperature regulation, and electrical measurements in a controlled atmosphere with a software kernel that controls the instruments and synchronizes the data streams. A user-friendly interface allows us to program multistep experiments controlling all the instruments and data acquisition by a specifically designed scheduler. We tested our system on a thin film of alkoxy-substituted phthalocyanines deposited on a test pattern with interdigitated electrodes. We studied the optical and electrical behavior in the proximity of the bulk phase transition to isotropic liquid, identifying a few ordered monolayers anchored to the substrate above the transition temperature.

Scientific Reports, 2016

High-resolution microscopy techniques have been extensively used to investigate the structure of ... more High-resolution microscopy techniques have been extensively used to investigate the structure of soft, biological matter at the nanoscale, from very thin membranes to small objects, like viruses. Electron microscopy techniques allow for obtaining extraordinary resolution by averaging signals from multiple identical structures. In contrast, atomic force microscopy (AFM) collects data from single entities. Here, it is possible to finely modulate the interaction with the samples, in order to be sensitive to their top surface, avoiding mechanical deformations. However, most biological surfaces are highly curved, such as fibers or tubes, and ultimate details of their surface are in the vicinity of steep height variations. This limits lateral resolution, even when sharp probes are used. We overcome this problem by using multifrequency force microscopy on a textbook example, the Tobacco Mosaic Virus (TMV). We achieved unprecedented resolution in local maps of amplitude and phase shift of the second excited mode, recorded together with sample topography. Our data, which combine multifrequency imaging and Fourier analysis, confirm the structure deduced from averaging techniques (XRD, cryoEM) for surface features of single virus particles, down to the helical pitch of the coat protein subunits, 2.3 nm. Remarkably, multifrequency AFM images do not require any image postprocessing.

We describe a method based on electron beam lithography to fabricate patterns of fractal islands ... more We describe a method based on electron beam lithography to fabricate patterns of fractal islands on a surface. The island morphology resembles that of a random deposition of particles in a diffusion-limited aggregation regime in 2-D, which is often encountered in the growth of atoms and molecules upon ultrahigh vacuum sublimation. With our fabrication protocol, the morphological parameters of the fractal islands (correlation length, fractal dimension, coverage, and roughness) can be controlled. The fabricated structures can be used as templates for investigating the interplay of self-affinity on thin film nucleation and growth, the adsorption of functional molecules, and the anchoring of living cells. Also they can be exploited as masters for nanoimprinting lithography and replica molding.