Assessing the Cytotoxicity of Engineered Nanoparticles: Applications and Implications

This work examines the cytotoxicity of nanoparticles applied in two engineered systems: (I) chemical mechanical planarization (CMP) and (II) membrane water treatment. Nanoparticle cytotoxicity is central to both sections: Part I characterizes the interactions of CMP nanoparticles with cell membranes following their use and Part II investigates the efficacy of antibacterial silver nanoparticles as they are applied in membrane treatment. During CMP, abrasive silica, ceria, and alumina nanoparticles contact the base of integrated circuit devices, producing an atomically smooth surface. Following CMP, these nanoparticles enter the environment through the wastewater treatment system. CMP nanoparticles were characterized to determine physicochemical changes incurred during processing that may alter their environmental fate and cytotoxicity. No significant changes in size, charge, or aggregation behaviors were observed. Interactions of CMP nanoparticles with model cell membranes were assessed using Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). Ceria and alumina nanoparticles did not interact strongly with model cell membranes, likely due to stabilizing slurry additives that remained effective even at high dilutions. Silica nanoparticles showed the strongest tendency to attach to supported lipid bilayers, with significant attachment detected at concentrations as low as 1 mg/L. Attachment was correlated with epithelial cell membrane damage observed by collaborators at North Carolina A&T State University. In Part II of this dissertation effort, I explored how the antibacterial nature of silver nanoparticles, when coupled with the hydrophilicity of polydopamine, can be harnessed to decrease the detrimental impact of biofouling on low pressure membranes. This work demonstrated that the hydrophilicity provided by the polydopamine coating decreased the initial rate of bacterial deposition by almost 50%. However, over the course of 3 days of filtration, only the combination of both polydopamine and silver nanoparticles was able to improve the rate of clean water production, increasing the flux to more than 175% of the unmodified membrane. The unique properties associated with nanomaterials can be implemented in a variety of innovative environmental engineering applications. In designing these applications, the full life cycle of the nanoparticles must be considered