Optimizing Functionality of Ion Channel Biosensing using Stochastic Resonance

Abstract

Stochastic resonance refers to the increased sensitivity of a system when a finite level of noise is applied to the system. This counter-intuitive concept is evidenced by a maximum in the signal-to-noise ratio with respect to applied noise level. We have applied this technique to a system of alamethicin ion channels incorporated in a planar lipid bilayer. When used as a molecular biosensor, an enhancement of the signal-to-noise ratio of such a system improves the sensor's limit of detection. Thus, by adding noise to the biosensor, we can maximize its sensitivity. We also show how this technique can be used to design an inherently optimal molecular biosensor. By varying the lipid membrane area, the alamethicin concentration, and applied voltage in each system, we control the level of noise internal to the system. Then, by noting the level of external noise that induces stochastic resonance, we inferred the level of internal noise that each variable introduces to the system. In doing so, we found that microphonic noise, which is introduced by the lipid membrane, most significantly influences the signature of stochastic resonance. Thus, we have shown that by tuning the membrane area to induce an optimal level of microphonic noise, one can design a molecular biosensor that inherently induces stochastic resonance.