Effect of SAM Chain Length on Mediated Amperometric Detection of Glucose

Self-assembled monolayers with reactive terminal functionality are frequently used for constructing chemical sensors.  The sensors can subsequently be modified by covalent attachment or electrostatic deposition of other materials to introduce specificity at the surface for the sensing application.  Electrostatic deposition is a simple method used to build structures at an interface, and is a method that can be easily adapted for biological molecules (e.g. proteins, enzymes, etc.) without compromising the integrity of the protein/enzyme.  When depositing biological molecules, however, the chain length can affect the kinetics of the glucose oxidase/glucose reaction.  This research used cyclic voltammetry to measure the Michaelis-Menton kinetics of the glucose oxidase reaction with glucose in the presence of a mediator.  The Michaelis-Menton kinetics were measured using three different thiols of varying lengths.  The length of the chain was shown to have an effect where the shortest chain had significantly different kinetics compared to the longer chains.