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Structure toxicity relationship analysis was conducted using principal component analysis (PCA) for a panel of nanoparticles that included dry powders of oxides of titanium, zinc, cerium and silicon, dry powders of silvers, suspensions of polystyrene latex beads and dry particles of carbon black, nanotubes and fullerene, as well as diesel exhaust particles. Acute in vitro toxicity was assessed by different measures of cell viability, apoptosis and necrosis, haemolytic effects and the impact on cell morphology, while structural properties were characterised by particle size and size distribution, surface area, morphology, metal content, reactivity, free radical generation and zeta potential. Different acute toxicity measures were processed using PCA that classified the particles and identified four materials with an acute toxicity profile: zinc oxide, polystyrene latex amine, nanotubes and nickel oxide. PCA and contribution plot analysis then focused on identifying the structural properties that could determine the acute cytotoxicity of these four materials. It was found that metal content was an explanatory variable for acute toxicity associated with zinc oxide and nickel oxide, while high aspect ratio appeared the most important feature in nanotubes. Particle charge was considered as a determinant for high toxicity of polystyrene latex amine.

Abstract: Despite being widely used in agriculture, food production and environmental monitoring and regarded as on-line chromatograph in petrochemical and biochemical industries, near infrared spectroscopy (NIR) has found difficulties in its application to processes of particle formation through crystallisation or precipitation where solids suspended in solutions cause problems in instrumentation as well as distortion of the spectra. The research work reported here was motivated by the hypothesis that the effect of particles on the NIR spectra in effect brings an opportunity instead: the spectra might contain useful information of both the solid and liquid phases. Through carefully designed experiments using both glutamic acid solutions and slurries of varied solid concentrations and particle size and temperature ranges and with the help of chemometric data analysis, it was found that the NIR spectra clearly contain sensitive information about the size, solid concentration, liquid concentration as well as polymorphs of crystals, providing the possibility of using the instrument for simultaneous measurement of the multiple properties of both phases. [Copyright &y& Elsevier]