Supported phospholipid bilayers and transport of heavy metals across them

摘要

To start their negative (or positive) role in plants or in human body, the elements and the compounds, which are present in polluted environment, must be transported into these organisms, more precisely, into their cells. In other words, each pollution particle, which takes part further in metabolic processes, must be transported across the cell membranes. Similar processes are realized in the opposite way - out of the cells as well as in and out of any sub-cellular structure. Detail elucidation of transport mechanisms is prerequisite for understanding of distribution of pollutants in real cells of more complex organisms (leaves, roots or the whole plants, animals or men) and for their possible control in the future. Because the real bio-membranes and the transporting processes realized across them are very complicated, the model membranes have been used for elucidation of the basic transporting steps. This article deals with simulation, characterization, description, and elucidation of the above mentioned transport processes on the example of some heavy (hazardous) metals, i.e., of cadmium and of lead. Because cations of these metals do not exist only as separate ions, it is necessary to take into account their existence in complexes. Therefore the attention was paid to their complexes with low molecular weight organic acids (LMWOAs) and their transporting processes. This contribution summarizes the results achieved using supported phospholipid model membranes. The ion channels, which are responsible for transport of some particles across the cell membranes, were replaced in the reported experiments by ionophores (valinomycin and calcimycin). The tested membranes and processes were characterized using electrochemical methods (electrochemical impedance spectroscopy, cyclic voltammetry, anodic stripping voltammetry (ASV), conductometry, etc.) and optical spectroscopy. This manuscript presents new knowledge in this field, first part of which was presented one year ago at this conference.