Hydrogen bonding and weak noncovalent linkages control the structures of macromolecules and play an important role in many membrane processes. Macroscopic modifications in the transport properties can often be attributed to simple intermolecular interactions. H-bonds and electrostatic interactions can be responsible for dramatic macroscopic domino effects [1]. Modelling based on ab-initio approaches allow addressing these nanoscale interactions without using adjustable parameters. Thus, in this presentation two "cases study", where ab-initio modelling provided information concerning the role of nanoscale interactions in pronounced macroscopic changes, are illustrated. The correlation between noncovalent interactions and the enhanced affinity of imprinted polymer membranes toward a geno-toxin template is highlighted. Quantum calculations are compared with experiments in order to draw the link. The H-bonds and electrostatic interactions among polymeric fragments are comparable to the strength of the same interactions occurring between polymer and geno-toxin molecule, as shown in Fig.1. Thanks to this competition, the availability of free carboxylic groups in the nanocavities of the polymer increases and in turn the affinity of the imprinted membrane [2]. Figure 1 Fragment-fragment and template-fragments interactions Afterwards, a computational study, focused on the interactions between fragments of sulfonated polystyrene-divinylbenzene, neutralized with Mg2+, Ca2+ and Na+ cations, as shown in Fig. 2, is illustrated. Figure 2 Hydrated polymer fragments and confined water molecules Nanoscale interactions are compared with the fluxes of some sugars across the cation exchange membrane, which markedly change as function of the nature of the counter ion [3]. The role of water molecules, anchored to the fragments (i.e. confined in the polymer matrix) is crucial since they work as a glue between the various fragments. For obtaining a good correlation with the macroscopic fluxes, the interactions exerted and experimented by the confined water must necessarily be taken into account. While the nanoscale interactions among polymeric fragments are not directly measurable, the mobility of the confined water molecules can be correlated with the investigated interactions and it is measurable. Although the main purpose of this study was the influence of the tested counter-ions on the sugar fluxes, nevertheless, the achieved conclusions, concerning the interactions of the confined water, are of general validity. [1] G. De Luca, A. Gugliuzza, E. Drioli, J. Phy. Chem. B 2009, 113, 5473-5477 [2] G. De Luca, L. Donato, S. G. Del Blanco, F. Tasselli, E. Drioli, J. Phy. Chem. B, 2011, 115, 9345-9351 dx.doi.org/10.1021/jp2006638 [3] A. Fuoco, Ph.D. Thesis Universitè Paul Sabatier, Toulouse, France, 2015
Nanoscale interactions controlling macroscopic membranes features
2015
Abstract
Hydrogen bonding and weak noncovalent linkages control the structures of macromolecules and play an important role in many membrane processes. Macroscopic modifications in the transport properties can often be attributed to simple intermolecular interactions. H-bonds and electrostatic interactions can be responsible for dramatic macroscopic domino effects [1]. Modelling based on ab-initio approaches allow addressing these nanoscale interactions without using adjustable parameters. Thus, in this presentation two "cases study", where ab-initio modelling provided information concerning the role of nanoscale interactions in pronounced macroscopic changes, are illustrated. The correlation between noncovalent interactions and the enhanced affinity of imprinted polymer membranes toward a geno-toxin template is highlighted. Quantum calculations are compared with experiments in order to draw the link. The H-bonds and electrostatic interactions among polymeric fragments are comparable to the strength of the same interactions occurring between polymer and geno-toxin molecule, as shown in Fig.1. Thanks to this competition, the availability of free carboxylic groups in the nanocavities of the polymer increases and in turn the affinity of the imprinted membrane [2]. Figure 1 Fragment-fragment and template-fragments interactions Afterwards, a computational study, focused on the interactions between fragments of sulfonated polystyrene-divinylbenzene, neutralized with Mg2+, Ca2+ and Na+ cations, as shown in Fig. 2, is illustrated. Figure 2 Hydrated polymer fragments and confined water molecules Nanoscale interactions are compared with the fluxes of some sugars across the cation exchange membrane, which markedly change as function of the nature of the counter ion [3]. The role of water molecules, anchored to the fragments (i.e. confined in the polymer matrix) is crucial since they work as a glue between the various fragments. For obtaining a good correlation with the macroscopic fluxes, the interactions exerted and experimented by the confined water must necessarily be taken into account. While the nanoscale interactions among polymeric fragments are not directly measurable, the mobility of the confined water molecules can be correlated with the investigated interactions and it is measurable. Although the main purpose of this study was the influence of the tested counter-ions on the sugar fluxes, nevertheless, the achieved conclusions, concerning the interactions of the confined water, are of general validity. [1] G. De Luca, A. Gugliuzza, E. Drioli, J. Phy. Chem. B 2009, 113, 5473-5477 [2] G. De Luca, L. Donato, S. G. Del Blanco, F. Tasselli, E. Drioli, J. Phy. Chem. B, 2011, 115, 9345-9351 dx.doi.org/10.1021/jp2006638 [3] A. Fuoco, Ph.D. Thesis Universitè Paul Sabatier, Toulouse, France, 2015I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
