Hofmeister Phenomena

Hofmeister specific ion effects are well established, occurring in a wide range of chemical and biological systems. However, the precise nature of the interactions between the ions and the species of interest is not clearly understood. Specific ion effects can be particularly important in bioelectrochemistry, where ions in the form of the electrolyte are an essential requirement for the electrochemical process. The effect of electrolyte on the electrochemical response is usually presumed to have little or no effect on the redox potential nor on the faradaic currnet. However, the nature of the ions present in solution can affect the properties of an enzyme, including properties such as protein folding and enzymatic activity.

>>Mini-review on Electrolyte effects on enzyme electrochemistry.

The electrolytes used in enzymatic biosensors or biofuel cells have always been considered to be inert. However, recent studies have demonstrated that this assumption is not correct and that the nature of the electrolyte needs to be considered. Ion specific interactions can occur with the faradaic response observed in both direct and mediated electron transfer being modulated by the nature of the salt used in solution. Specific ion effects arise from the Hofmeister series, which is well established in studies of protein systems but not in electrochemical studies of redox enzymes. Recent experimental and theoretical work on explaining the Hofmeister effect is described.