Effects of 3-Aminopropyl Triethoxysilane (APTES) on Stability, Optical Properties and Morphology of Gold Nanoparticles

The purpose of this study was to determine the extent to which 3-aminopropyl triethoxysilane (APTES) could impact the stability, optical properties and morphology in gold (Au) colloidal solutions. Several concentrations ranging from 48mM to 475mM were utilized throughout the duration of the study. Ultraviolet–visible absorption results confirm extensive red shifts in the absorbance spectrum from 500nm to 650nm respectively. SEM characterization confirms that red shifts are largely due to aggregation of nanoparticles as opposed to particle growth. With the addition of APTES, the photoluminescent properties of the gold increased as a function of the concentration as well as time. Our findings suggest that the degree of aggregation and ultimately the change in optical properties is a strong function of the concentration of APTES, pH and time; independent of being in solution or adhered to a substrate. This work is important for future use of synthesized or purchased nanoparticles that will be manipulated or modified using this chemical.