Creation and regulation of ion channels across reconstituted phospholipid bilayers generated by streptavidin-linked magnetite nanoparticles.

In this work, we explore the nature of ion-channel-like conductance fluctuations across a reconstituted phospholipid bilayer due to insertion of ∼100 nm sized, streptavidin-linked magnetite nanoparticles under static magnetic fields (SMFs). For a fixed bias voltage, the frequency of current bursts increases with the application of SMFs. Apart from a closed conductance state G(0) (≤14 pS), we identify four major conductance states, with the lowest conductance level (G(1)) being ∼126 pS. The number of channel events at G(1) is found to be nearly doubled (as compared to G(0)) at a magnetic field of 70 G. The higher-order open states (e.g., 3G(1), 5G(1)) are generally observable at larger values of biasing voltage and magnetic field. When the SMF of 145 G is applied, the multiconductance states are resolved distinctly and are assigned to the simultaneous opening and closing of several independent states. The origin of the current bursts is due to the instantaneous mechanical actuation of streptavidin-linked MNP chains across the phospholipid bilayer. The voltage-controlled, magnetogated ion channels are promising for diagnoses and therapeutic applications of excitable membranes and other biological systems.