Laboratory of Biophysics of Ionic Liquids

Neutron Scattering, Atomic Force Microscopy and Computer Simulations

Research overview
Our main research line focuses on the interaction of ionic liquids (ILs) - a vast and relatively new class of organic electrolytes - with the basic building blocks of living matter, including lipid bilayers and biomembranes, proteins and amyloids, and cells, with the aim to understand the chemical-physical properties relevant to the development of applications in pharmacology, nano-bio medicine and nano-bio technology. Neutron scattering, atomic force microscopy and computer simulations are the three major techniques used for these investigations, which are combined with a number of complementary approaches, including cell-biology assays.
Our second line of research is aimed at the development of a new neutron scattering method/spectroscopy for dynamics. This novel approach is based on the detection of the solely neutrons that are scattered into the elastic line and offers several advantages in comparison to standards methods for dynamics, which make it particularly suitable for the study of biomolecules. Theoretical approaches and Monte Carlo computations are the two methods employed here, which are completed by test experiments at large-scale neutron scattering facilities.
Our third research line focuses on water structure and dynamics at (bio)-interfaces and in confinement, with a special focus on water molecules confined at biological surfaces. Other interests include the investigation of the dynamics-function relationship in proteins. Neutron scattering and classical molecular dynamics simulations are the two major approaches adopted in these studies.
Methods:
Neutron scattering, atomic force microscopy and computer simulations are the three major approaches we use with the aim to link molecular, if not, atomistic-scale mechanisms to behaviours and processes taking place at the meso-scale (Fig. 1). Among neutron scattering approaches, we use elastic and quasi-elastic neutron scattering (Fig. 2), neutron spin-echo (Fig. 3), neutron reflectivity (Fig. 4), and small-angle neutron scattering (Fig. 5). Advanced atomic force microscopy modes are used in our investigations, which are combined with fluorescence and confocal optical microscopies for correlative analysis (Fig. 6). A series of complementary approaches are also used, which include static and dynamic light scattering, calorimetry, electron microscopies, Raman and infrared spectroscopies and a palette of different biological methods as, for example, cell survival assays, western blotting of key proteins, flow cytometry, cell migration and scattering assays.
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Fig. 1 - A representative example. Neutron reflectometry allowed to determine the partitioning of ionic liquid (IL) cations between lipid and aqueous phases of a model biomembrane, which quantitatively agreed with the classical molecular dynamics (MD) simulations carried out on the same system. The analysis of the MD trajectories suggested that IL-cations alter the viscoelasticity of the membrane, which has been investigated then experimentally by atomic force microscopy.
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Fig. 2 - Elastic and quasi-elastic neutron scattering is one of the many neutron scattering techniques that we routinely use in our research. The instrument pictured in the figure is the IN16B spectrometer installed at the Institute Laue-Langevin, Grenoble, France (link), which we recently used to measure dynamics in hydrated proteins and to test our new neutron spectroscopy method for dynamics. Along with IN16B, we routinely use other QENS spectrometers in many large-scale facilities worldwide, including: HFBS at the National Institute of Standards and Technology, Maryland, USA (link), BASIS at the Oak-Ridge National Laboratory, Tennessee, USA (link), IRIS at the Rutherford Appleton Laboratory in the Oxfordshire, UK (link); FOCUS at the Paul Scherrer Institute, Villigen, Switzerland (link); SPHERES at the Heinz-Maier-Leibnitz Zentrum, Munich, Germany (link).
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Fig. 3 - Neutron spin-echo spectroscopy is one of the many neutron scattering techniques that we routinely use in our research. The instrument pictured in the figure is the Neutron Spin-Echo spectrometer installed at the Centre for Neutron Research at the National Institute of Standards and Technology, Maryland, USA (link), which we have recently used to measure how ionic liquids alter bending elasticity and thickness fluctuations of lipid vesicles that are now well known to the general public for their use as carriers in the mRNA-based Covid-19 vaccine bio-technology.
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Fig. 4 - Neutron reflectometry is one of the many neutron scattering techniques that we routinely use in our research. The instrument pictured in the figure is MAGIK, one of the neutron reflectometers installed at the Centre for Neutron Research at the National Institute of Standards and Technology, Maryland, USA (link), which we recently used to measure ionic liquid absorption in supported lipid bilayer. Along with MAGIK, we use the neutron reflectometer FIGARO installed at the Institute Laue-Langevin, Grenoble, France (link).
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Fig. 5 - Small-angle neutron scattering (SANS) is another neutron technique that we routinely use in our research. The instrument pictured in the figure is one of the SANS machines installed at National Institute of Standards and Technology, Maryland, USA (link), which we recently used to determine the partitioning of ionic liquid (IL) cations between lipid vesicles and their aqueous solvent. The knowledge of IL-partitioning is necessary for the development of IL-based applications in pharmacology, bio-medicine and bio-nanotechnology.
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Fig. 6 - Atomic force microscopy (AFM) is another technique we routinely use in our research. Recently, we used AFM to determine the effect of ionic liquids on cell membrane mechno-elasticity. Alterations in cell membrane mechano-elasticity were observed in several pathological conditions and are relevant in bacteria and virus dissemination. As a results, being able to act on cell viscoelasticity with ionic liquids can lead to high-impact applications in pharmacology, bio-medicine and, more in general, bio-nanotechnology.