Surface-Enhanced Raman Spectroscopic Analysis of Anatase Titanium Dioxide Nanoparticles: Investigation of the Key Factors

摘要

Characterization of titanium dioxide nanoparticles (TiO2-NPs) is significant to ensure its quality and safety in applications and facilitate risk assessment. Surface-enhanced Raman spectroscopy (SERS) is a novel technique for characterization of the size of TiO2 particles. Herein, we investigated the key factors in the SERS analysis of anatase TiO2-NPs using a variety of well-characterized particle reference materials (8-173 nm) and gallocyanin (GLN) as a ligand for SERS. The result shows that regardless of the particle and ligand concentrations used, the R-value obtained from the ratio of TiO2 (144 cm~(-1)) to GLN (1639 cm~(-1)) peak intensities was able to distinguish between the nano-sized particles from the micro-particles, although no significant difference was observed between 8 to 65 nm particles. This means particle size is the primary factor that affected the R. The concentration of the NPs and the ligand, respectively, could also affect the R as secondary factors and common dispersion methods such as adjusting the pH and the sonication did not affect the R. However, this method did not work in presence of a stronger binding dispersing agent such as sodium pyrophosphate (SPP). This study fulfilled the knowledge gap regarding the key factors that impacts the SERS analysis of TiO2-NPs which will facilitate the further application of this technique in the analysis of TiO2-NPs in food products and environmental matrices.