Plenary Lecture

Analysis of Metal/Metalloid Oxide Nanoparticles in Water

Professor Edward Lai
Co-author Samar Alsudir
Department of Chemistry
Carleton University

Abstract: Increasing production and applications of metal/metalloid oxide nanoparticles (NPs) has greatly raised the demand for new analytical techniques capable for trace quantification in water to assess their environmental impacts and health risks. A new analytical method was developed for the sensitive detection of alumina (Al2O3), ceria (CeO2), silica (SiO2), titania (TiO2) and zinc oxide (ZnO) as model NPs. This approach was based on the formation of molecular layers and polymeric coatings on the NPs directly in water to selectively add chromophores to their surface for enhanced ultraviolet (UV) light absorption in capillary electrophoresis (CE) analysis. One unique advantage is the ability to identify nanoparticles by observing either a stronger peak or a shifted migration time. Controlled polymerization of 2-hydroxypropyl methacrylate (HPMA) on SiO2 NPs added a coating of poly-2-hydroxypropyl methacrylate (PHPMA). A second coating with polydopamine produced PDA-PHPMA-SiO2 NPs as confirmed by dynamic light scattering (DLS) and transmission electron microscopy. Chitosan coating after HPMA binding was selective for SiO2 NPs in the presence of TiO2 NPs in 10 mM Na2HPO4. Selective enhancement was achieved for TiO2 in the presence of SiO2, Al2O3 and ZnO NPs in 100 mM Tris using Triton X-100 and single-stranded DNA. Polyethylene glycol coating of ssDNA-TiO2 NPs further enhanced the UV detection sensitivity in CE analysis, by providing electrosteric stabilization. Monolayer adsorption of dithiothreitol and cysteine were selective towards ZnO NPs in 10 mM Na2HPO4 even in the presence of Al2O3, CeO2, SiO2 and TiO2 NPs. The new approach provides a simple, rapid and efficient CE-based analytical methodology towards the selective detection of SiO2, TiO2 and ZnO NPs with enhanced sensitivity. The methodology can be further improved by coupling CE to laser-induced fluorescence, inductively coupled plasma, and mass spectrometry.

Brief Biography of the Speaker: Ed Lai obtained his Ph.D. degree in Analytical Chemistry from the University of Florida (U.S.A.) in 1982, under the supervision of Professor Jim Winefordner. He is currently Associate Dean of Science (Undergraduate Affairs) and Full Professor (Chemistry & Biochemistry) at Carleton University who has accumulated 34 years of research experience and knowledge in bio-organic and environmental analytical chemistry. He is a fellow of the Chemical Institute of Canada, has published 135 scientific papers, and presented over 130 talks/posters at conferences. His research interests are instrumental analysis of biochemical and environmental samples, using photochemical, electrochemical, chromatographic and electrophoretic techniques to develop new analytical methods for enhanced sensitivity and selectivity. He has a wealth of experience in synthesizing highly functional molecularly imprinted polymers for specific recognition of pharmaceuticals, mycotoxins and endocrine disrupting compounds in water. Current research is focused on the detection of nanoparticles in air and water samples, development of nanocarriers for drug delivery, and investigation of DNA binding with inorganic oxide nanoparticles. He also teaches electronic instrumentation at the graduate level.

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