Thermodynamic and adsorption properties of
protein monolayer electrochemistry (PME) are examined for Pseudomonas aeruginosa
azurin (AZ) immobilized at an
electrode modified with a networked film of monolayer-protected clusters (MPCs) to assess if nanoparticle films of this nature offer a more homogeneous adsorption interface compared to traditional self-assembled monolayer (SAM) modified
electrodes. Specifically, electrochemistry is used to assess properties of surface coverage, formal potential, peak broadening, and electron transfer (ET) kinetics as a function of film thickness. The modification of a surface with
dithiol-linked films of MPCs (Au(225)C6(75)) provides a more uniform binding interface for AZ that results in voltammetry with less peak broadening (<110mV) compared to
SAMs (>120-130mV). Improved homogeneity of the MPC interface for
protein adsorption is confirmed by atomic force microscopy imaging that shows uniform coverage of the
gold substrate topography and by electrochemical analysis of film properties during systematic desorption of AZ, which indicates a more homogeneous population of adsorbed
protein at MPC films. These results suggest MPC film assemblies may be used in PME to provide greater molecular level control of the
protein adsorption interface, a development with applications for strategies to study
biological ET processes as well as the advancement of biosensor technologies.