Lauryldimethylamine oxide (LDAO), also known as dodecyldimethylamine oxide (DDAO), is an amine oxide–based zwitterionic surfactant, with a C12 (dodecyl) alkyl tail. It is one of the most frequently-used surfactants of this type.[4] Like other amine oxide–based surfactants it is antimicrobial, being effective against common bacteria such as S. aureus and E. coli,[1] however, it is also non-denaturing and can thus be used for protein purification.
At high concentrations, LDAO forms liquid crystalline phases.[5] Despite having only one polar atom that is able to interact with water – the oxygen atom (the quaternary nitrogen atom is hidden from intermolecular interactions), DDAO is a strongly amphiphilic surfactant: it forms normal micelles and normal liquid crystalline phases. High amphiphilicity of this surfactant can be explained by the fact that it forms not only very strong hydrogen bonds with water: the energy of DDAO – water hydrogen bond is about 50 kJ/mol,[6] but it also has high experimental partition coefficient in non-polar medium, as characterized by experimental logP 5.284[7]
^Hoffmann, H. (1990). "Correlation between surface and interfacial tensions with micellar structures and properties of surfactant solutions". Interfaces in Condensed Systems. Progress in Colloid & Polymer Science. Vol. 83. pp. 16–28. doi:10.1007/BFb0116238. ISBN978-3-7985-0840-8.
^Kocherbitov, V.; Veryazov, V.; Söderman, O. (2007). "Hydration of Trimethylamine-N-oxide and of Dimethyldodecylamine-N-oxide: An Ab Initio study". J. Molec. Struct. Theochem. 808 (1–3): 111–118. doi:10.1016/j.theochem.2006.12.043.