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Issue 5, 2008
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Collective headgroup conformational transition in twisted micellar superstructures

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Abstract

Predictions on amphiphilic self-assemblies traditionally rely on considerations on molecular shape and charge of the surfactant. In the case of functional surfactants a more sophisticated toolbox becomes necessary to design amphiphiles encoding chemical functionalities that provide additional responsive properties to their self-assemblies. Here we report on a comprehensive and combined structural–spectroscopic characterization of 1,2-dilauroyl-phosphatidyl-adenosine (DLPA) micelles in phosphate buffer. The temperature dependence, more precisely the thermal history of the sample, is explicitly taken into account. The experimental data, supplemented with MD simulations, indicate the presence of two possible states at room temperature, characterized by distinctly different structural properties that depend on the thermal history of the sample. The twisted superstructures, produced by aging DLPA micelles through intermicellar assembly of locally cylindrical aggregates at room temperature, collapse upon warming at 35 °C, yielding aligned filaments and/or wormlike structures. The initial superstructures cannot be recovered by thermal inversion. The reason for this behaviour is that the thermal activation causes a redistribution of synanti conformations of adenosine headgroups, as indicated by spectroscopic results (NMR, CD, FTIR), which is then collectively frozen thanks to molecular constraints present in the aggregate.

Graphical abstract: Collective headgroup conformational transition in twisted micellar superstructures

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Publication details

The article was received on 07 Jan 2008, accepted on 27 Feb 2008 and first published on 25 Mar 2008


Article type: Paper
DOI: 10.1039/B800210J
Citation: Soft Matter, 2008,4, 1102-1113
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    Collective headgroup conformational transition in twisted micellar superstructures

    F. Baldelli Bombelli, D. Berti, S. Milani, M. Lagi, P. Barbaro, G. Karlsson, A. Brandt and P. Baglioni, Soft Matter, 2008, 4, 1102
    DOI: 10.1039/B800210J

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