Assessment of change in physicochemical properties and cellular toxicity of Pre-and Post-CMP silica slurries

With the large-scale use of silica nanoparticles (SNPs) in Chemical Mechanical Planarization (CMP) processes, it is very important to study their potential effect on human occupational health and safety and its impact on the environment. In addition, it is believed that subtle changes in nanoparticle usage and state can lead to huge differences in their physicochemical properties and hence their activity and toxicity. In this study, we conducted a comprehensive assessment of changes in the physicochemical properties, along with cellular toxicity and uptake before and after the CMP process. Colloidal silica nanoparticles (SNPs) and its slurries (pre and post CMP) were characterized for size, surface area, particle size distribution, zeta potential, trace elements and functional groups. Next, the slurries containing the colloidal SNPs (pre and post CMP) were exposed to A549 human lung epithelial cells at various concentrations to investigate the effect on cellular toxicity and corresponding cellular uptake. It was observed that the SNP-based slurries were toxic when exposed to A549 cells without dilution. However, after serial dilution of 100x and 10,000x, the colloidal SNP-based slurries showed minimal to no cell toxicity. Lastly, cellular uptake studies showed that the colloidal SNPs were taken up by A549 cells at 100x dilution level.