- Title
- Rapid Synthesis of Thiol-Co-Capped CdTe/CdSe/ZnSe Multi-Core-Shell QDs and Their Encapsulation in Liposomes and Chitosan Nanoparticles; Comparative Bio-compatibility Studies Using Hela and Vero Cells
- Creator
- Daramola, Olamide Abiodun
- ThesisAdvisor
- Krause, Rui
- ThesisAdvisor
- Tseki, Potlaki
- Subject
- Chitosan
- Subject
- Chitosan nanoparticles
- Subject
- Quantum dots
- Subject
- Liposomes
- Subject
- Toxicity
- Subject
- Cadmium telluride
- Subject
- Cadmium selenide
- Subject
- Zinc selenide
- Date
- 2023-03-31
- Type
- Academic theses
- Type
- Doctoral theses
- Type
- text
- Identifier
- http://hdl.handle.net/10962/422617
- Identifier
- vital:71962
- Identifier
- DOI 10.21504/10962/422617
- Description
- The common method that has been used to reduce the toxicity posed to living cells by CdTe Quantum Dots (QDs) is through the synthesis of CdTe multi-core-shells nanoparticles. In this process, the surface of CdTe QDs is usually coated by less toxic ZnS or ZnSe shells. This heterostructure compound does not only reduce the toxicity of CdTe QDs but can also be used in applications such as deep tissue imaging. The heterostructures can be in numerous forms such as CdTe/CdSe/ZnSe or CdTe/CdSe/ZnS or CdTe/CdS/ZnS multi-core-shell QDs. However, the drawbacks attributed to the fabrication of these compounds is long synthesis times (6- 24 h) in achieving the highest wavelength emission maxima. Others are the use of toxic reagents and poor reproducibility of synthesized materials. An additional problem is that the ZnSe or ZnS coating is insufficient to completely protect the highly toxic Cd metal from escaping into immediate solution. This limits their use in biochemistry and with living systems. Liposomes and biopolymers such as chitosan are known to be environmentally friendly compounds that have been used in various studies as delivery systems for QDs and model drugs for drug delivery applications. They are generally non-toxic and highly bio-compatible. In this study, the rapid synthesis of thiol-co-capped CdTe/CdSe/ZnSe multi-core-shell QDs with a maximum reaction time of 35 mins, gave reliable QDs with emission maxima at 625 nm. The multi-core-shell QDs were encapsulated in two different bio-compatible environments, namely liposome and chitosan nanoparticles (CNP) at 14 different formulations (F) for liposome and 12 different formulations for CNP. Cytotoxicity and florescence imaging studies using HeLa and Vero cells, were used to investigate the improved bio-compatibility. Various characterization techniques were used to elucidate the optical properties, morphology and physico-chemical properties of the QDs and nanocomposites. Two of the best formulations, QD-liposome vesicles (LVs)-F12 and QD-CNP-F9 (with chitosan), demonstrated high loading efficiencies of 42 ± 6 % and 59 ± 5 %, respectively. While the plain CdTe QDs showed high toxicity, some of the encapsulated materials, QD-LVs-F1 and F12, depicted no-toxicity against the cells (IC50 > 0.5 mg/ml). The QDs also retained most of their fluorescence and properties and could easily be tracked in cells and visualized around the nucleus, indicating the successful internalization of the QDs in the cytosol. These results shows that encapsulation of CdTe multi-core-shell QDs in liposomes produce better bio-compatibility compared to multi-core-shell QDs and better than CNP coating. These particles therefore show good promise in cell-labelling, drug delivery studies. Their core-shell nanoparticles have also shown good behavior in enhancing the memory of a device which is based on some recent collaborated works.
- Description
- Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Format
- computer, online resource, application/pdf, 1 online resource (188 pages), pdf
- Publisher
- Rhodes University, Faculty of Science, Chemistry
- Language
- English
- Rights
- Daramola, Olamide Abiodun
- Rights
- Use of this resource is governed by the terms and conditions of the Creative Commons "Attribution-NonCommercial-ShareAlike" License (http://creativecommons.org/licenses/by-nc-sa/2.0/)
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | DARAMOLA-PHD-TR23-90.pdf | 3 MB | Adobe Acrobat PDF | View Details Download |