Author: Deng, Zhiying
Title: Aggregation kinetics of gold-DNA (Au-DNA) nanoparticles in aquatic environments
Advisors: Jiang, Yi (CEE)
Degree: M.Sc.
Year: 2019
Subject: Nanoparticles
Hong Kong Polytechnic University -- Dissertations
Department: Department of Civil and Environmental Engineering
Pages: v, 41 pages : color illustrations
Language: English
Abstract: Recently, gold-DNA nanoparticles (Au-DNA) exhibits application potentials in sensing, biomedical, and environmental fields, likely leading to release of such nanoparticles into environment with unclear impact on the ecosystem. To better predict the environmental fate of Au-DNA nanoparticles, a systematical investigation of their colloidal stability becomes a necessity. In this research, we synthesized gold nanoparticles functionalized by different length scales (15 - 40 nucleotides) of DNA (Au-DNA) to investigate their aggregation behaviors in typical aqueous environments. The determination of the critical coagulation concentrations (CCCs) of Au-DNA nanoparticles under various electrolytes background (NaCl, CaCl2 and MgCl2), respectively was accomplished by Time-resolved dynamic light scattering (TR-DLS). Results showed that functionalization of DNA onto gold nanoparticles significantly enhanced their colloidal stability compared to their precursive form (citrate-stabilized gold nanoparticles). Aggregation behavior of tested Au-DNA nanoparticles is affected by ionic strength, cation types, and DNA length. By analyzing the impacts of electrolytes and DNA length, it can be reasonably assumed that the aggregation of Au-DNA nanoparticles is not only affected by van der Waals attraction and electrostatic repulsion, but also steric hindrance. Furthermore, a representative natural organic matter (NOM), Suwannee River Humic Acid, was introduced to observe the impact of NOM on aggregation behavior of Au-DNA nanoparticles. Au-DNA nanoparticles displayed a further strengthened colloidal stability in the presence of SRHA, which might be due to the adsorption of humic substances onto Au-DNA nanoparticles, resulting in the increase of steric stabilization.
Rights: All rights reserved
Access: restricted access

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