Page 26 - ILLS Annual Report 2018

SOFT MATTER
Samantha Micciulla. Italian
ILL
‘Scientists have the unique privilege of looking at the most intimate side of nature to learn from its excellence. In my research, understanding the behaviour of supramolecular assemblies at interfaces, as governed by the interactions
between their fundamental constituents, is not only driven by genuine curiosity; it is also motivated by the belief that each small, individual contribution to scientific knowledge is a resounding achievement for a better life on our planet.’
3PhaseNR: a new approach for structural studies of soft interacting interfaces
Fluid interfaces grazing angles reflectometer FIGARO
Interactions between soft interfaces have a major influence on the function of biological entities and the properties of colloidal systems. The nature of
such forces can be revealed from
the interfaces’ structural response to variations in the surface separation,
for which surface-sensitive scattering techniques are best suited. We have developed a novel approach for probing distance-dependent structures of soft buried, interacting soft thin films by neutron reflectometry, starting from independent molecular layers at a solid/water and water/oil interface
at tuneable interaction distances.
A variety of conditions can rapidly
be realised by tuning the mutual interaction pressure and, in turn, the distance and molecular structure.
Figure 1
From left to right: schematic representation of the experimental set-up
of a solid/liquid/liquid interface, a molecular picture of the interacting interfaces and the volume fraction distribution of components across the interface.
AUTHORS
S. Micciulla and Y. Gerelli (ILL)
R.A. Campbell (Manchester University, UK)
E. Schneck (Max Planck Institute of Colloids and Interfaces, Potsdam, Germany)
ARTICLE FROM
Langmuir (2018)—doi: 10.1021/acs.langmuir.7b02971
REFERENCES
[1] P.C. Lau, T. Lindhout, T.J. Beveridge, J.R. Dutcher and J.S. Lam, J. Bacterial. 191 (2009) 6618
[2] T. Nylander, R.A. Campbell, P. Vandoolaeghe, M. Cardenas, P. Linse and A.R. Rennie, Biointerphases 3 (2008) 3 FB64
[3] W.M. De Vos, L.L.E. Mears, R.M. Richardson, T. Cosgrove, R.M. Dalgliesh and S.W. Prescott, Rev. Sci. Instr. 83 (2012) 113903
[4] I. Rodriguez-Loureiro, V.M. Latza, G. Fragneto and E. Schneck, Biophys. J. 114 (2018) 1624
Interactions involving biological membranes govern complex phenomena such as cell adhesion and the formation of bacterial biofilms [1]. Such soft interfaces exhibit a close relation between their interaction properties, in terms of range and strength, and the spatial organisation of the molecules residing at the interface. Molecular conformations and ion distributions show a considerable response when interfaces approach and mass exchange across them occurs [2]. Knowledge of such structural details is thus valuable, and sometimes a prerequisite, to understanding and controlling these interfacial interactions.
Approaches developed so far, using rigid or flexible substrates under compression [3] or surfaces separated by swelling in humid air [4], present certain limitations, such as intolerance to impurities, a restricted range of surface separation and the impossibility of independent layer characterisation prior to their interaction.
Within the framework of a Röntgen-Ångström Cluster grant (3phaseNR), we have developed a new experimental set- up that allows us to bring two arbitrary soft interfaces from non-interacting conditions, i.e. macroscopic separation, to controlled interactions at nanometric separation distances (figure 1).
As schematically illustrated in figure 1, one of the interfaces is created by modifying a solid substrate (solid/liquid interface), the other by functionalisation of a fluid interface between two immiscible liquids (liquid/liquid interface). Planar geometry and the macroscopic size of the contact
ANNUAL REPORT 2018