The Use of Hexaamineruthenium(III) Redox Marker for the characterization of SAM-Au Amperometric Sensors

Chemically modified electrodes (CME's) by self-assembled monolayers (SAM's) of alkanethiols are extensively studied because of their potential applications in many fields from surface chemistry, to biochemistry, to electroanalytical chemistry. The layer defectivity is one of the most critical feature that affects the reproducibility of the final sensors, hence a careful electrode design and preparation is required. In the present work the preparation and characterization of long chain thiol Au-SAM's of controlled defectivity is described. In particular, the apparent standard rate constants of the Ru(NH3)63+/2+ redox couple are determined as a function of the degree of coverage for three different linear chain alkylthiols (n-decane-, n-dodecane- and n-octadecane-thiol). The results are discussed in term of the electron transfer model at partially blocked surfaces.