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Thesis
Improving Properties of Tin Sulfide Quantum Dots for Bioimaging Applications Through Zinc Sulfide Coating
Master of Science (M.S.), Drexel University
Jun 2018
DOI:
https://doi.org/10.17918/0emy-z753
Abstract
Interest in quantum dots has continued to grow due to their unique properties especially in biomedical applications. Compared to common fluorescent dyes used for bioimaging applications, quantum dots have better quantum yield, while displaying longer photostability. Additionally, some quantum dots emit near infrared wavelengths, which make them suitable for tissue imaging. However, most of the commercially available quantum dots contain heavy metals that can create toxic levels of heavy metals when the quantum dots begin to deteriorate. In this research, a solution coating approach using zinc sulfide (ZnS) to improve the properties of a non-toxic tin sulfide (SnS) core quantum dot that has a near infrared emission wavelength for bioimaging applications is presented. This type of core/shell structure has been shown to passivate the surface, while maintaining the optical properties of the core quantum dot. It was found that the coating approach improved the photoluminescence of the SnS core by 20x without changing the near infrared emission wavelength. Multiple characterization methods were performed to gain understanding of the coating process and the resulting properties. XPS and EDS showed that small amounts of ZnS was indeed present on the surface of SnS particles, while TEM showed that the ZnS coating caused some clustering of SnS particles leading to a redshift in the UV/Vis absorption spectra and the sharpening of XRD peaks. Furthermore, it was shown that the suspension stability of the SnS/ZnS quantum dots can be enhanced through the use of 3-Mercaptopropionic acid as an additional capping molecule.
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Details
- Title
- Improving Properties of Tin Sulfide Quantum Dots for Bioimaging Applications Through Zinc Sulfide Coating
- Creators
- Huai-Yu Peter Cheng - DU
- Contributors
- Wei-Heng Shih (Advisor) - Drexel University (1970-)Hao Cheng (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xi, 64 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- Materials (Science and) Engineering (Metallurgical Engineering) [Historical]; College of Engineering (1970-2026); Drexel University
- Other Identifier
- 8240; 991014632941104721