Resource type
Thesis type
(Thesis) M.Sc.
Date created
2019-07-04
Authors/Contributors
Author: Zhang, Yifei
Abstract
An on-site fluorometric method for the qualitative detection of major arsenic species, arsenite, As(III), and arsenate, As(V), in water is presented in this thesis. Both As(III) and As(V) are toxic ions that are found in drinking water or water effluents worldwide. Building upon DNA-capped metal oxide nanoparticles, it has been shown that both As(III) and As(V) can be quantitated with a paper-based fluorometric assay. In particular, fluorescently labelled DNA aptamers were first adsorbed onto CeO2 nanoparticles where the fluorescence was initially quenched. After the addition of either As(III) or As(V), the DNA strands were released from the surface due to strong and specific DNA (aptamer)-As(III/V)(ligand) interactions which resulted in fluorescence recovery. It was demonstrated that such a detection scheme can be realized on an arrayed paper substrate; glass fiber filter paper was first modified to be superhydrophobic and then patterned photochemically to create arrayed reaction sites. The signal readout is based on smartphone-imaging, i.e., analyze the RGB intensities of the assay photo taken under UV irradiation with a smartphone. These paper assays provided great performance for testing water samples containing As(III) and As(V), with detection limits of 29 nM and 38 nM, response ranges from 20 nM to 100 µM and from 10 nM to 100 µM, respectively. The satisfactory detection sensitivity (below the WHO standard, 80 nM), high selectivity, and wide response range augment the potential application of these paper-based fluorometric assays for on-site arsenic detection in water.
Identifier
etd20348
Copyright statement
Copyright is held by the author.
Scholarly level
Supervisor or Senior Supervisor
Thesis advisor: Yu, Hua-Zhong
Member of collection
Model