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Stable aqueous ZnS quantum dots obtained using (3-mercaptopropyl) trimethoxysilane as a capping molecule

Li, Hui and Shih, Wan Y. and Shih, Wei-Heng (2007) Stable aqueous ZnS quantum dots obtained using (3-mercaptopropyl) trimethoxysilane as a capping molecule. NANOTECHNOLOGY, 18 (49).

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We have examined the synthesis and stability of ZnS quantum dots (QDs) using an all-aqueous route at pH = 12 with (3-mercaptopropyl) trimethoxysilane (MPS) as the capping molecule. The MPS-capped ZnS QDs obtained were well dispersed with a particle size around 5 nm and a cubic zinc blende crystalline structure. The QDs exhibited optimal photoluminescence (PL) emission when the MPS:Zn:S ratio was between 1/4:2:1 and 1/2:2:1. Compared with the earlier obtained ZnS QDs caped with 3-mercaptopropionic acid (MPA), the MPS-capped ZnS QDs exhibited a similar, high quantum yield, 42% and 25% for MPS:Zn:S = 1/2:2:1 and 1/4:2:1, respectively, but much better photostability. With the MPS:Zn:S ratio of 1/4:2: 1, we showed that at room temperature and under the normal laboratory lighting conditions, the MPS-capped QDs were able to maintain their PL intensity for more than 50 days without degradation. We further showed that the MPS-capped QDs were stable not only in their synthesis solution but also in deionized (DI) water and in phosphate buffer saline (PBS) solution. The QDs with MPS:Zn:S = 1/2:2:1 were able to stay at 50 degrees C for more than 20 h without degrading the PL intensity. They were also stable under continuous UV exposure for 3 h. With the high quantum yield and significantly improved photostability, the MPS-capped ZnS QDs could be good imaging tools for many biological applications.

Item Type:Article
Subjects:Biomedical Science > Nanobiotechnology
Physical Science > Quantum phenomena
Material Science > Nanostructured materials
ID Code:6280
Deposited By:IoN
Deposited On:22 Dec 2009 11:30
Last Modified:22 Dec 2009 11:30

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