Neurotransmitter Biomolecule Transfers Across Liquid/Liquid Interface Through A Thick Organic Membrane-Modified Electrode

Electrochemical studies at liquid/liquid interfaces (L/L, or soft interfaces) have disclosed a biomimetic model to mimic charge transfers at cytomembrane surface. Herein, we reported two neurotransmitter biomolecules of dopamine and adrenalone across the L/L interface by a thick organic membrane-modified electrode. This system comprised polarized electrode/oil and oil/water interfaces in series in which the electron transfer (ET) of redox 7,7,8,8-tetracyanoquinodimethane (TCNQ) at electrode/oil interface drove ion transfer (IT) of biomolecules at oil/water interface. This ET-IT coupled reaction overcame the limitation of polarized potential window at conventional single polarized L/L interface. The crucial design of a thick organic membrane could ensure the generated TCNQ anions maintained at electrode/oil interface during the voltammetry, which could not result in interruptions to biomolecule transfers. Through this system, their Gibbs transfer free energies were accurately determined (44.4 and 39.4 kJ mol(-1) for dopamine and adrealone, respectively). Moreover, facilitated biomolecule transfers were evaluated by crown ionophores where both facilitated numbers and constants were determined simultaneously. Owing to the simple electrochemical setup, this system would hold great potentials in future hydrophilic biomacromolecule transfers, such as DNA, peptides and proteins.