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1.3 PHYSICAL SCIENCES
Nanotoxicology has emerged as a discipline of a result of the revolution of nanotechnology. While nanotoxicology is in its infancy, there is a lack of toxicological data for nanoparticles, naturally occurring or commercially produced. The need for information regarding mechanisms associated with nanoparticle uptake by biological cells, as well as internalisation and accumulation of nanoparticles once penetrating cell membranes, is imperative. This project will focus on the internalisation studies of surface modified polystyrene nanoparticles. An in vitro lung model consisting of A549 (ATCC No: CRL185), a carcinogenic lung epithelial cell line, was employed to investigate the biocompatibility of nano scaled polystyrene particles in pulmonary systems. Biological effects of 40nm and 100nm carboxylated surface modified nanopolystyrene, 50nm and 100nm neutral nanopolystyrene and 60nm aminated nanopolystyrene were monitored. Prior to cellular studies, a full particle size characterisation was carried out using Dynamic Light Scattering, Atomic Force Microscopy, Zeta Potential and Electronic Spectroscopy. The cytotoxic effects of nano scale 40nm and 100nm carboxylated, 50nm and 100nm neutral nanopolystyrene and 60nm aminated nanopolystyrene were then evaluated using four cytotoxic endpoints, namely the Neutral Red, Alamar Blue, Comassie Blue and MTT assays, with both neutral and carboxylated modified particles exhibiting no cytotoxic effect at any of the concentrations or timepoints examined. Aminated nanoparticles were observed to elicit some toxic effects in cells, over certain test concentrations and exposure times. Cellular internalisation of the fluorescently labelled particles was monitored with the aid of fluorescent confocal microscopy. Nanoparticle internalisation and accumulation within specifically labelled cell organelles was then monitored and verified with the aid of commercially available transfection labelling kits. Raman microscopy was then employed to spectroscopically image biological cells previously exposed to fluorescently labelled 50nm and 100nm polystyrene nanoparticles. The use of K-means clustering and principal component analysis (PCA), demonstrated that the technique was capable of localising the nanoparticles and identifying the subcellular environment based on the molecular spectroscopic signatures.
Dorney, J. (2013). Polystyrene: a potential standard for developing iIn vitro cellular tracking methods for nanotoxicology. Doctoral Thesis. Technological University Dublin. doi:10.21427/D75C76