To bring the capabilities of analytical affinity chromatography to bear on interactions concerning biomembranes, researchers have frequently utilized gel-entrapped phospholipid vesicles or covalent lipid-mimetic silica particles as stationary phases. The ability to alter membrane compositions and the increased realism of the former system should enable a broader range of interaction types to be evaluated relative to the latter materials; however the analytical performance is affected by the gel support's lack of compatibility with higher performance chromatography formats. This presentation describes material and methodology development with solid supported phospholipid bilayers to study metal ion interactions by liquid chromatography. Ion adsorption and binding influences a wide range of bilayer properties and membrane protein functions, and the low affinity nature of the interaction often makes evaluation by other methods difficult. Consequently, it is an appealing class of interactions to use in evaluation of the materials and chromatographic methodology described in this presentation.Robust, spherical supports generated from agglomerated sub-micron St�ber silica colloids are utilized to support diverse formulations of phospholipids as stationary phases in fused silica capillaries. ICP-MS detection enables the evaluation of group I and II ion interactions with phospholipids and with the ionophores nigericin and gramicidin on the nanomolar scale. The structural properties of the supports, namely: large uniform pores (>50 nm), the lack of small pores and surface features that may affect bilayer properties (a result of the smooth surface of the dense colloids), and the relatively inert nature of the thermally deactivated silica, make them effective supports of the non-covalent films within a relatively high performance format. Robust measurements of the relative adsorption and binding selectivity arising from the simultaneous evaluation of ion groups and the blocking efficacy of divalent ions on gramicidin will be presented.

New materials for the chromatographic analysis of ion interactions at phospholipid bilayers

248th National Meeting (2014)

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