Salvatore

Salvatore Assenza

Postdoctoral Researcher

Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid
Módulo 5 (Office 501), Facultad de Ciencias, C/ Francisco Tomás y Valiente 7, 28049 Madrid (Spain)

News

02 September 2019
New article on cholesteric liquid crystals under confinement just published on Scientific Reports!

24 July 2019
Our Review on the soft matter foundations of food macrocomponents is finally out in Nature Reviews Physics! You can access it for free clicking here

06 May 2019
New article on enzymatic reactions in lipid-based nanoconfinement published on Angewandte!

25 April 2019
Double update today: Our article on amorphous water in nanoconfinement was featured on Chemistry World

8 April 2019
Very exciting news! Our new article " Soft biomimetic nanoconfinement promotes amorphous water over ice " has just been published on Nature Nanotechnology!

5 March 2019
New article " The interplay of channel geometry and molecular features determines diffusion in lipidic cubic phases " is finally out on the Journal of Chemical Physics!

15 February 2019
Our article " Curvature and bottlenecks control molecular transport in inverse bicontinuous cubic phases " published in The Journal of Chemical Physics was selected as 2018 Editors' choice !

08 January 2019
With the new year comes the beginning of a new startling experience as a Postdoctoral Researcher in the " Scanning Probe Microscopy Theory & Nanomechanics Group " at Universidad Autónoma de Madrid


Research Interests

My research interests are quite heterogeneous, and span several fields. Click on an image or visit the "Research" tab to find out what I've been working on!

Lipidic Mesophases
Lipidic Mesophases
Biomolecular Systems
Biomolecular Systems
Polymer Physics
Polymer Physics
Complex Networks
Complex Networks

Contact & Links

Research Interests



Lipidic Mesophases

Lipidic mesophases are interesting objects obtained by mixing water and lipids in suitable proportions. Depending on the specific details of the lipids employed as well as on lipid concentration and temperature, mesophases with different microscopic structures are obtained, including arrangements as hexagonal, lamellar and cubic phases. Lipidic mesophases are at the center of intense research due to many different applications, most of which are based on the molecular transport within these systems. My research on the topic is focused on understanding the interplay between structure and transport, with the goal of providing a reliable theoretical framework for devising related applications with tailored properties.
For example, in a paper we have provided the necessary theoretical framework to analyze the results of the so-called diffusion setup. Comparison of the theoretical predictions against experimental data from systems with known features shows an excellent quantitative agreement without any adjustable parameter, thus appointing our theory as a reliable tool for data analysis.
In another work, by combining theory and experiments we showed that polymer diffusion within cubic mesophases can be regulated by as many as three different mechanisms, reminescent of Zimm, Rouse and reptation dynamics.
More recently, we have studied how the nanostructure of cubic phases affects diffusion by Brownian Dynamics simulations. Our results show that the effective diffusion coefficient is regulated by a subtle interplay between curvature and bottlenecks of the network of water channels. Moreover, comparison with experiments enables assessing the amount of immobilized water starting from the theoretical prediction. The results from this study can be used by experimental researchers to estimate the diffusion coefficient of a molecule diffusing within a cubic phase of interest. To ease such application, you can find here a tool that computes the effective diffusion coefficient starting from the structural parameters of the cubic phase.
Lipidic Cubic Phases also provide good environments for enzymatic reactions. For example, we have studied how how the activity of the enzyme aldolase is enhanced when within a cubic phase and, based on the known structure of the enzyme and of mesophases, we suggested a microscopic picture of how such an enhancement can be achieved.

Publication List

  1. Six-fold director field configuration in amyloid nematic and cholesteric phases
    M. Bagnani, P. Azzari, S. Assenza and R. Mezzenga
    Sci. Rep. 9, 12654 (2019)

  2. Soft condensed matter physics of foods and macronutrients
    S. Assenza and R. Mezzenga
    Nature Reviews Physics 1, 551 (2019)
    (Click here to access it for free)

  3. Spatiotemporal Control of Enzyme‐Induced Crystallization Under Lyotropic Liquid Crystal Nanoconfinement
    J. J. Vallooran, S. Assenza and R. Mezzenga
    Angew. Chem. Int. Ed. 58, 7289 (2019)

  4. Impact of Molecular Partitioning and Partial Equilibration on the Estimation of Diffusion Coefficients from Release Experiments
    R. Ghanbari, S. Assenza*, P. Zueblin and R. Mezzenga
    Langmuir 35, 5663 (2019) ( *Co-first author )

  5. Soft biomimetic nanoconfinement promotes amorphous water over ice
    L. Salvati Manni, S. Assenza*, M. Duss, J. J. Vallooran, F. Juranyi, S. Jurt, O. Zerbe, E. M. Landau and R. Mezzenga
    Nat. Nanotechnology 14, 609 (2019) ( *Co-first author )

  6. The interplay of channel geometry and molecular features determines diffusion in lipidic cubic phases
    R. Ghanbari, S. Assenza and R. Mezzenga
    J. Chem. Phys. 150, 094901 (2019)

  7. Confinement‐Induced Ordering and Self‐Folding of Cellulose Nanofibrils
    K. B. Smith, J.‐N. Tisserant, S. Assenza, M. Arcari, G. Nyström and R. Mezzenga
    Adv. Sci. 6, 1801540 (2019)

  8. Efficient Asymmetric Synthesis of Carbohydrates by Aldolase Nano-Confined in Lipidic Cubic Mesophases
    T. Zhou, J. J. Vallooran, S. Assenza, A. Szekrenyi, P. Clapés and R. Mezzenga
    ACS Catal. 8, 5810 (2018)

  9. Curvature and bottlenecks control molecular transport in inverse bicontinuous cubic phases
    S. Assenza and R. Mezzenga
    J. Chem. Phys. 148,054902 (2018)
  10. Shape of a Stretched Polymer
    A. S. Sassi, S. Assenza* and P. De Los Rios
    Phys. Rev. Lett. 119, 037801 (2017) ( *Corresponding Author )
  11. Diffusion of Polymers through Periodic Networks of Lipid-Based Nanochannels
    R. Ghanbari, S. Assenza*, A. Saha and R. Mezzenga
    Langmuir 33,3491 (2017) ( *Co-first author )
  12. Quantifying the transport properties of lipid mesophases by theoretical modelling of diffusion experiments
    L. M. Antognini, S. Assenza, C. Speziale and R. Mezzenga
    J. Chem. Phys. 145,084903 (2016)
  13. Quantifying the role of chaperones in protein translocation by computational modeling
    S. Assenza*, P. De Los Rios and A. Barducci
    Front. Mol. Biosci. 2,8 (2015) ( *Corresponding Author )
  14. Universal Behavior in the Mesoscale Properties of Amyloid Fibrils
    S. Assenza, J. Adamcik, R. Mezzenga and P. De Los Rios
    Phys. Rev. Lett. 113, 268103 (2014)
  15. Emerging Meso- and Macroscales from Synchronization of Adaptive Networks
    R. Gutiérrez, A. Amann, S. Assenza, J. Gómez-Gardeñes, V. Latora, and S. Boccaletti
    Phys. Rev. Lett. 107, 234103 (2011)
  16. Emergence of structural patterns out of synchronization in networks with competitive interactions
    S. Assenza, R. Gutiérrez, J. Gómez-Gardeñes, V. Latora, and S. Boccaletti
    Sci. Rep. 1,99 (2011)
  17. Enhancement of cooperation in highly clustered scale-free networks
    S. Assenza, J. Gómez-Gardeñes and V. Latora
    Phys. Rev. E 78,017101 (2008)

Software Tools

Here you can find some tools I developed to facilitate analysis of experimental results on cubic phases. Click on the title of the tool to use it. The tools can be freely used, and relevant references are listed for each of them. Please cite the appropriate articles if you use the tools in your research!


This tool estimates the effective diffusion coefficient of a hydrophilic molecule within a cubic phase with known structural features, by following the analysis reported in Assenza et al. The basic assumption is that the diffusing particle is prevented to access the lipid bilayer by short-range hard repulsion. Moreover, a layer of water in proximity of the lipid heads is assumed to be tightly bound to the latter, thus significantly slowing down diffusion in this region. The needed input parameters are: the size of the lattice parameter, as measured by SAXS; the weight percentage of water used to produce the cubic phase; the density of the lipid; a reference value of the diffusion coefficient of the molecule in pure water (D0) at a given temperature (T0, it can be different than the temperature used in the experiment with the cubic phase); the working temperature of the experiment (Texp); the thickness of the layer of "bound water" in proximity of the lipid heads (good values usually lie between 0.6 nm and 1.2 nm, corresponding to a layer thickness equal to roughly two and four water molecules respectively). The outputs of the tool are the total fraction of bound water xb (i.e. # of bound water molecules divided by total # of water molecules) and the effective diffusion coefficient D. The default input values correspond to glucose diffusion in a Pn3m cubic phase based on monolinolein at 37 oC (Antognini et al.)

Relevant Literature:
- Assenza and Mezzenga, J. Chem. Phys. 148:054902 (2018)
- Antognini, Assenza, Speziale and Mezzenga, J. Chem. Phys. 145:084903 (2016)


Inputs
Lattice Parameter (nm):
Water (% weight):
Lipid Density (g/cm3):
D0 (10-5cm2/s):
T0 (oC):
Texp (oC):
w (nm):



Results
xb
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D (10-5cm2/s)
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Collaborators

Rubén Pérez
Rubén Pérez
Universidad Autónoma de Madrid (Spain)
Raffaele Mezzenga
Raffaele Mezzenga
ETH Zürich (Switzerland)
Paolo De Los Rios
Paolo De Los Rios
EPFL (Switzerland)
Alessandro Barducci
Alessandro Barducci
Centre de Biochimie Structurale de Montpellier (France)
Vito Latora
Vito Latora
Queen Mary, University of London (United Kingdom)
Jesús Gómez Gardeñes
Jesús Gómez Gardeñes
Universidad de Zaragoza (Spain)
Alberto Sassi
Alberto Sassi
EPFL (Switzerland)
Chiara Speziale
Chiara Speziale
ETH Zürich (Switzerland)
Livia Salvati Manni
Livia Salvati Manni
ETH Zürich (Switzerland)
Reza Ghanbari
Reza Ghanbari
ETH Zürich (Switzerland)



Alumni

Alberto Sassi
Alberto Sassi
EPFL (Switzerland)
Luca Antognini
Luca Antognini
ETH Zürich & EPFL (Switzerland)
Paride Azzari
Paride Azzari
ETH Zürich (Switzerland)