Effect of organic crosslinkers on the formation of a homogeneous monolayer of TiO2 nanoparticles on a silica glass

Abstract Immobilization techniques for various compounds have been widely used in a variety of industrial fields for surface modification purposes. Immobilization of metallic nanoparticles using organic coupling agents, however, needs to be explored in more details although extensive investigations have been performed. In this study, it was aimed at preparing a homogeneous monolayer of anatase titanium dioxide nanoparticle (TNP) immobilized on a silica glass using three organic coupling agents, including glutaraldehyde (GTA), poly(L-lysine) (PLL), and bis-(3-aminopropyl)-terminated poly(ethylene glycol) (PEG). TNP-immobilized layer prepared using the simple adhesion was prepared for a comparison purpose. Simple adhesion or use of GTA as a coupling agent resulted in the formation of TNP aggregates. On the other hand, we found that homogeneous monolayer of immobilized TNPs was achieved when PLL or PEG was used as a coupling agent. Among the organic coupling agent-mediated TNP-immobilized layer, PEG-mediated immobilization generated more homogeneous and fully covered monolayer of TNPs than others. According to atomic force microscopic analysis, the surface roughness of TNP-immobilized layer formed by PEG was 0.16 nm which was the smallest value among the samples of interest. X-ray photoelectron spectroscopic analysis provided clear evidence that immobilized layers are composed of titanium. The current study demonstrates that PEG is the most efficient coupling agent for TNP immobilization on silica glass. Our results can be further utilized for immobilization of photocatalyst, surface modification for biomaterials and drug delivery system.