Transport of Organic Ions Through Bilayer Lipid Membranes
Additional Funding Sources
This research project was supported by the Idaho State Board of Education - Higher Education Research Council, and by the National Science Foundation under Award No. 1554166.
Abstract
The hydrophobic core of the cell membranes constitutes an impenetrable barrier for inorganic ions due to the large energy penalty required for polar compounds to cross it. However, organic ions present dual, amphiphilic characteristics, hence lipid membranes may allow their transport. In this endeavor, we investigated the transport of organic ions TPP and TPB through artificial, planar bilayer membranes composed of natural lipids and cholesterol. Our explorations indicated measuring the membrane conductance in the presence of organic ions. The conductance of the membrane was estimated from the slope of the I-V plots recorded in response to linearly-variable voltage stimuli. As anticipated, the membrane conductance was modulated by the organic ion concentration in the bulk electrolyte. In addition, saturation-like effects occurred either at higher concentration of organic ions, or at large values of the transmembrane voltage stimulus. Such non-linearity may be explained by assuming that the organic ion transport is a physical process strongly limited by ionic diffusion at the water-membrane interface. This work opens novel avenues for the development of transmembrane carriers capable of transporting drugs and other physiologically-relevant compounds into the cytosol of cells and in a non-destructive manner.
Transport of Organic Ions Through Bilayer Lipid Membranes
The hydrophobic core of the cell membranes constitutes an impenetrable barrier for inorganic ions due to the large energy penalty required for polar compounds to cross it. However, organic ions present dual, amphiphilic characteristics, hence lipid membranes may allow their transport. In this endeavor, we investigated the transport of organic ions TPP and TPB through artificial, planar bilayer membranes composed of natural lipids and cholesterol. Our explorations indicated measuring the membrane conductance in the presence of organic ions. The conductance of the membrane was estimated from the slope of the I-V plots recorded in response to linearly-variable voltage stimuli. As anticipated, the membrane conductance was modulated by the organic ion concentration in the bulk electrolyte. In addition, saturation-like effects occurred either at higher concentration of organic ions, or at large values of the transmembrane voltage stimulus. Such non-linearity may be explained by assuming that the organic ion transport is a physical process strongly limited by ionic diffusion at the water-membrane interface. This work opens novel avenues for the development of transmembrane carriers capable of transporting drugs and other physiologically-relevant compounds into the cytosol of cells and in a non-destructive manner.