Characterizing the pH Dependence of Surface Charge for Silica Nanoparticles Made by Amino Acid Synthesis

Abstract

Silica nanoparticles are silica spheres in the micron size range. Because of their shape and ordered arrangement, these nanoparticles serve important purposes in high-tech industries and modern applications such as cancer therapy, drug and DNA delivery systems, ultrasensitive analysis, and nanoparticle films. Applications depend on order in packing of nanoparticles, which in turn depends on particle charge. Silica nanoparticles were synthesized using published methods and the pH of the solution bathing the nanoparticle was altered. The nanoparticle solutions were then characterized by size with SAXS lighting scattering and by surface charge with an electrophoretic method. Though zeta-potential tests provided variable data with each batch of particles, the overall pattern was consistent. It was found that zeta potential decreases as pH becomes more acidic.