Self-Assembled Two-Dimensional Array of Gold Nanoparticles with Different Size for the Sensing Application

Abstract

Self-assembled two-dimensional array of gold nanoparticles (GNPs) on the glass substrate was systematically investigated in terms of glass cleaning, K2CO3 addition, GNP size, and pH of gold colloids. An ambient-air plasma treatment produced a highly-activated glass surface with the lowest air/water contact angles and K2CO3 addition is very effective to preserve the optical properties of gold nanoparticles for a long time. Small GNPs (≤40 nm) was uniformly arrayed on the amine-functionalized glass through the optimization process of electrostatic attractions between positively-charged glass and negatively-charged gold nanoparticles. For large GNPs (≥50 nm) that resulted in discrete (or loosely-packed) array on the glass substrate, pH adjustment of gold colloids (from pH 11 to 9) produced more densely-packed array of GNPs with less void areas, probably due to the reduction of electrostatic repulsion forces between large gold nanoparticles.