Dị tụ vật liệu nano, hematit trong môi trường nước - Luận án Khanh An Huynh

LIST OF FIGURES

LIST OF TABLES

1. INTRODUCTION

1.1. Two Popular Engineered Nanomaterials: Carbon Nanotubes and Silver Nanoparticles

1.2. Fate and Transport of Carbon Nanotubes and Silver Nanoparticles Aquatic Environments

1.3. Toxicity of Carbon Nanotubes and Silver Nanoparticles

1.4. Objectives and Scopes of Dissertation

2. HETEROAGGREGATION OF MULTIWALLED CARBON NANOTUBES AND HEMATITE NANOPARTICLES: RATES AND MECHANISMS

2.1. Materials and Methods

2.1.1. Preparation of Carbon-Based Nanomaterials and Hematite Nanoparticles

2.1.2. Characterization of Carbon-Based Nanomaterials and HemNPs

2.1.3. Time-Resolved Dynamic Light Scattering

2.1.4. Determination of Homoaggregation Kinetics

2.1.5. Determination of Heteroaggregation Rates

2.1.6. Cryogenic Transmission Electron Microscopy

2.2. Results and Discussion

2.2.1. Physicochemical Properties of Carbon-Based Nanomaterials and HemNPs

2.2.2. Electrokinetic Properties of Carbon-Based Nanomaterials and HemNPs

2.2.3. Homoaggregation Kinetics of Carbon-Based Nanomaterials and HemNPs

2.2.4. CNTs and HemNPs Undergo Exclusive Heteroaggregation at Low NaCl Concentration

2.2.5. Influence of CNT/HemNP Ratio on Rates of Heteroaggregation

2.2.6. Cryogenic TEM Imaging of CNT–HemNP Heteroaggregates

2.2.7. Proposed Heteroaggregation Mechanisms of CNTs and HemNPs

2.2.8. Influence of Humic Acid on Heteroaggregation Rates of CNTs and HemNPs

2.2.9. Heteroaggration Behavior of GO Nanosheets and C60 Nanoparticles with HemNPs

3. DISAGGREGATION OF HETEROAGGREGATES COMPOSED OF MULTIWALLED CARBON NANOTUBES AND HEMATITE NANOPARTICLES

3.1. Materials and Methods

3.1.1. Preparation and characterization of CNTs and HemNPs

3.1.2. Time-Resolved Dynamic Light Scattering

3.1.3. Determination of Power Delivered by Ultrasonication Bath

3.1.4. Determination of Degree of Disaggregation

3.2. Results and Discussion

3.2.1. Power of Ultrasonication Bath

3.2.2. Disaggregation of CNT Homoaggregates at pH 5

3.2.3. Disaggregation of CNT–HemNP Heteroaggregates at pH 5

3.2.4. Disaggregation of CNT–HemNP Heteroaggregates at Elevated pH

3.2.5. Disaggregation of CNT–HemNP Heteroaggregates in the Presence of Humic Acid

4. AGGREGATION KINETICS OF CITRATE AND POLYVINYLPYRROLIDONE COATED SILVER NANOPARTICLES IN MONOVALENT AND DIVALENT ELECTROLYTE SOLUTIONS

4.1. Materials and Methods

4.1.1. Silver Nanoparticle Synthesis and Characterization

4.1.2. Determination of Silver Nanoparticle and Dissolved Silver Concentrations

4.1.3. Electrophoretic Mobility Measurements

4.1.4. Time-Resolved Dynamic Light Scattering

4.1.5. Determination of Aggregation Kinetics

4.1.6. Detection of AgNP Dissolution

4.2. Results and Discussion

4.2.1. Physicochemical Properties of Citrate- and PVP-Coated AgNPs

4.2.2. Electrokinetic Properties of Citrate- and PVP-Coated AgNPs

4.2.3. Dissolution of Citrate- and PVP-Coated AgNPs at High Electrolyte Concentrations

4.2.4. Aggregation Kinetics of Citrate-Coated AgNPs in Monovalent Electrolyte Solution

4.2.5. Comparing Citrate-Coated AgNP Aggregation Kinetics with DLVO Theory

4.2.6. Aggregation Kinetics of Citrate-Coated AgNPs in Divalent Electrolyte Solutions

4.2.7. Comparing Aggregation Kinetics of PVP-Coated AgNPs with Citrate-Coated AgNPs

4.2.8. Influence of Humic Acid on Aggregation Kinetics of Citrate- and PVP-Coated AgNPs

5. HETEROAGGREGATION REDUCES ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES: EVIDENCE FOR NANOPARTICLE–CELL PROXIMITY EFFECTS

5.1. Materials and Methods

5.1.1. Preparation of Nanoparticles

5.1.2. Electrophoretic Mobility Measurements

5.1.3. Heteroaggregation of AgNPs and HemNPs

5.1.4. Preparation of Bacteria

5.1.5. Evaluation of the Effects of Heteroaggregation on Antimicrobial Activity of AgNPs

5.1.6. Determination of Dissolved Silver Concentrations at the Beginning and End of Incubation in the Absence of Bacteria

5.1.7. Cryo-TEM Imaging of Heteroaggregates

5.2. Results and Discussion

5.2.1. AgNPs Completely Inhibit Bacterial Growth at Sub-Lethal Concentration of Dissolved Silver in Bulk Solution

5.2.2. Heteroaggregation with HemNPs Reduces Antibacterial Activity of AgNPs

5.2.3. Heteroaggregation Inhibits Direct Contact or Close Proximity between AgNPs and Bacterial Cells

CONCLUSIONS AND KEY CONTRIBUTIONS