Effect of SAM Chain Length on Mediated Amperometric Detection of Glucose

Abstract

Alkanethiol self-assembled monolayers of three different chain lengths were used to immobilize glucose oxidase onto gold disk electrodes and the effect of the length on the kinetics of the electron-transfer reaction were investigated. 6 – mercaptohexanoic acid and 9 – mercaptononanoic acid was synthesized to provide a chain length shorter then the commercially available 11 – mercaptoundecanoic acid. The surface coverage of these SAMs, the detection sensitivity, and enzyme kinetics were investigated using cyclic voltammetry. Results showed that SAM of the 6-mercaptohexanoic acid had a higher degree of surface coverage as well as more efficient enzyme kinetics than expected.

Probing Qualitative Change in Intermolecular Forces from Hydrogen Bonding to Electrostatic Interaction on the Surface of Self-Assembled Monolayer

“…The chain length affects not only the surface coverage of the SAM but also the electron transfer rate to the surface. Scientists have investigated enzyme catalyst properties 9 and tribological properties 10 on the SAM surface by adjusting the chain length. The reason self-assembled monolayer is popular for building molecular scale membrane is it can generate layers with well-defined packing and density of specific molecules and then specific functions of SAM can be designed.…”