The Characteristic Self-assembly of Gold Nanoparticles over Indium Tin Oxide (ITO) Substrate

Abstract

Ordered array of gold nanoparticles (Au NPs) over ITO glass was investigated in terms of ITO pretreatment, particle size, and diamines with different chain length. Owing to the indium-tin-oxide (ITO) layer coated on the glass, the substrate surface has a limited number of hydroxyl groups which can produce functionalized amine groups for Au binding, which resulted in the loosely-packed array of Au NPs on the ITO surface. Diamine ligand as a molecular linker was introduced to enhance the lateral binding of adjacent Au NPs immobilized on the amine-functionalized ITO glass, consequently leading to the densely-packed array of Au NPs over the ITO substrate. The molecular bridging effect was strengthened with the increase of chain length of diamines: C-12 > C-8. The packing density of small Au NPs (< 40 nm) was significantly increased with the increase of C-8 diamine, but large Au NPs (> 60 nm) did not produce densely-packed array on the ITO glass even for the dosage of C-12 diamine.

Chemosensing on Miniaturized Plasmonic Substrates

“…Several studies report using different types of composed metallic/non-metallic NPs for increasing the LSPR sensitivity of biosensors [ 17 , 18 , 19 , 20 ]. Thus, indium tin oxide (ITO) was used for its conductivity and high optical transmittance, and due to their excellent conductive properties [ 21 , 22 , 23 ], an array of gold nanoparticles on ITO was used for SERS measurements [ 24 ]. Moreover, the plasmonic performance of metallic NPs depends on the chemical compositions and physical dimensions of the metallic nanoparticles [ 25 , 26 ].…”