Can Transition Metal Cations be Electrostatically Screened away from Biomembrane Interfaces?
Presented by Prof. Paul Cremer
Hosted by Prof. Wei Min
Abstract:
It has been known for over one hundred years that negatively charged surfaces in aqueous electrolyte solutions concentrate Group I and Group II metal ions into an electrical double layer directly adjacent to the solid/liquid interface. The increased local counterion density leads to the binding of divalent metal cations with anionic membrane lipids at significantly lower total ion concentrations than analogous interactions taking place in the bulk solution. Moreover, the enhanced binding can typically be screened away by introducing NaCl to the solution. Curiously, the same enhanced binding and screening effects appear to be far weaker when transition metal counterions, like Cu2+ or Ni2+ , are used instead. In this presentation it will be shown that transition metal counterions are far less susceptible to electrostatic screening and interfacial potential changes compared to Group I and Group II metal ions. This is because they are typically chelated in the bulk aqueous solution in coordination complexes with a wide variety of net charges. These results have important implications for the trafficking of transition metal ions in vivo as well as for their use in the fabrication of materials.
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