Seed mediated growth of gold nanoparticles on indium tin oxide electrodes: Electrochemical characterization and evaluation

The seed mediated growth of gold nanoparticles on indium tin oxide (ITO) surfaces is described, which provided a new method for the construction of gold nanoparticles-modified ITO electrodes even without using conventional linker molecules, such as (3-mercaptopropyl)trimethoxysilane (MPTMS). In this process, ultra-small gold seeds were formed and anchored on the ITO surfaces first. When the seeds-deposited ITO surfaces came into contact with the gold growth solution, the growth of gold nanoparticles occurred. The morphology of the as-prepared modified surface was found to be strongly dependent upon the substrate. On an MPTMS-silanized ITO, mostly gold nanospheres were formed (Au/MPTMS/ITO).In contrast, on a bare ITO, some high aspect ratio gold nanorods as well as large amounts of gold nanospheres were grown and directly attached (Au/ITO). The as-prepared two gold nanoparticles-modified ITO electrodes exhibited different electrochemical characteristics, attributed to the influence of MPTMS molecules. Compared with Au/MPTMS/ITO, the Au/ITO was more efficient in decreasing the heterogeneous charge transfer resistance and improving the reaction reversibility of [Fe(CN)(6)](3-)/[Fe(CN)(6)](4-) and exhibited more attractive bioelectrocatalytic properties. Due to the block effect of the thiol monolayer, Au/MPTMS/ITO depressed the selectivity for the determination of epinephrine (EP) in the presence of ascorbic acid (AA) while Au/ITO could improve the detection sensitivity and retain the selectivity.