Current bursts in lipid bilayers initiated by colloidal quantum dots

Inorganic semiconductor nanocrystals, also called quantum dots, have recently attracted considerable interest as fluorescent labels. We report that CdSe QDs initiate current bursts in lipid bilayer membranes upon application of a bias voltage. The current bursts observed resemble those produced by the peptaibol class of antibiotics such as alamethicin and trichorzins. The current fluctuations are dependent on the bias voltage and on the concentration of the quantum dots applied to the membrane. Our data suggest that quantum dots with dipole moments similar to alamethicin are influenced by an external electric field, which creates a torque resulting in the insertion into the lipid membrane. We predict that at least three quantum dots are required to form a pore due to aggregation that leads to a macroscopic conductance. (c) 2005 American Institute of Physics.