2014 Volume 82 Issue 9 Pages 712-719
Previously documented results on molecule manipulation using metal nanogates are comprehensively reviewed to conclude novel characteristics, which could be widely used for the developments of the systems at electrified interfaces. Novel systems to segregate molecules from self-spreading lipid bilayers in electrolyte solutions have been developed by using metal nanogate structures on solid surfaces. The spatial distribution of target molecules in the lipid bilayer changes depending on the molecule characteristics, such as charge, size, and flexibility. Energy dissipation during the spreading of the molecules on the surface contributes to the compression of the lipid bilayer at the nanogate, leading to the formation of a gradient of the electrochemical potential of the bilayer system including the target molecule in the vicinity of the nanogate (<100 nm from the gate). The gradient results in a segregation force being applied to target molecules in the order of 10−15 N per molecule. The segregation property can be tuned by changing the electrolytes, lipid molecules, temperature, and the width and surface hydrophobicity of the metal nanogate. Introduction of asymmetry to the nanogate leads to further effective diffusion control in a direction perpendicular to the spreading. It has been demonstrated that target molecules with a different number of glycolipid per protein in the lipid bilayer are effectively separated based on the Brownian ratchet mechanism.
