Hydrophobic metal complexes interaction with biological

INTERACTION OF HYDROPHOBIC METAL COMPLEXES AND ORGANOMETALLIC COMPOUNDS WITH BIOLOGICAL INTERPHASES... 

On the other hand, the presence of hydrophobic complexes is a prerequisite for partitioning and diffusion of metals into the lipid bilayer. In the following paragraphs, various types of metal complexes will be discussed, which are relevant to the interactions of metals in aquatic systems. The role of these various types of metal complexes with respect to interactions at the biological interphases will be systematically examined. 

In the following section, the role of the various types of complexes mentioned above will be discussed with regard to various mechanisms of interactions at biological interphases. It is clear that metal ions and hydrophilic complexes cannot distribute into the membrane lipid bilayer or cross it. The role of hydrophilic ligands has thus to be discussed in relation to binding of metals by biological ligands. In contrast, hydrophobic complexes may partition into the lipid bilayer of membranes (see below, Section 6). 

There is an abundant research on the interactions of HIOCs and metals with biological interphases, in which organic chemicals and metals are treated independently. However, few studies have considered the role of combinations of HIOCs with metals. There is a particular lack of mechanistic approaches. With regard to the metals, the FIAM has been very successful, but it remains to be shown under which conditions additional interactions, such as partitioning of hydrophobic complexes and uptake of specific complexes, are important for metal uptake and toxic effects. In particular, the role of hydrophobic complexes with both natural and pollutant compounds in natural waters has not yet been fully elucidated, since neither their abundance nor their behaviour at biological interphases are known in detail. 

Because of the complex nature of most biological samples, a single fractionation technique may not be adequate for the separation of the wide range of molecules present. Better resolution of some molecules is obtainal when properties other than differences in size are exploited. These include differences in ionic characteristics, affinity for other molecules and hydrophobicity. In separations that involve any one or more of these properties, the sample constituents interact with the column material and are then eluted with a suitable eluant. As a consequence of this interaction, and the use of eluants, whose properties may not closely resemble those of the medium found in vivo, the metal may dissociate from the ligand. In addition, as the complexity of the sample increases it is difficult to predict the behaviour of the various constituents. Undesirable effects leading to irreversible interaction between some molecules in the sample and the column packing material, degradation and decomposition of some constituents may result. Furthermore, it may be difficult to rid the column of certain trace metal contamination. 

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