Confirmation of membrane electroporation from flicker noise

Living systems interact with their environment through biological membranes. Charge movement across these membranes plays a key role in several natural processes and has been the subject of intense research. Charge can transport through the hydrophobic barrier of the membrane by means of ion channels, ionophores or electric-field-induced pores. Membrane electroporation results in a nonlinear I-V characteristic of the system. However, nonlinear behavior is exhibited by the majority of the inhomogeneous systems and hence is not a definite proof of pore formation. Noise measurement is a well accepted method of studying the charge transport in inhomogeneous systems and we report here our study of the noise spectral density in a planar lipid membrane, which is a model for more complex biological membranes to study the molecular processes involved in transmembrane charge conduction. Analysis of our results, in the light of similar experiments conducted in various inhomogeneous systems, confirms that nonlinearity here is the signature of membrane electroporation.