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Synthesis and bio-imaging application of highly luminescent mercaptosuccinic acid-coated CdTe nanocrystals.

Ying E, Li D, Guo S, Dong S, Wang J - PLoS ONE (2008)

Bottom Line: By selecting mercaptosuccinic acid (MSA) as capping agent and providing the borate-citrate acid buffering solution, CdTe nanocrystals with high quantum yield (QY >70% at pH range 5.0-8.0) can be conveniently prepared by this method.The influence of parameters such as the pH value of the precursor solution and the molar ratio of Cd(2+) to Na(2)TeO(3) on the QY of CdTe nanocrystals was systematically investigated in our experiments.Under optimal conditions, the QY of CdTe nanocrystals is even high up to 83%.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China.

ABSTRACT
Here we present a facile one-pot method to prepare high-quality CdTe nanocrystals in aqueous phase. In contrast to the use of oxygen-sensitive NaHTe or H(2)Te as Te source in the current synthetic methods, we employ more stable sodium tellurite as the Te source for preparing highly luminescent CdTe nanocrystals in aqueous solution. By selecting mercaptosuccinic acid (MSA) as capping agent and providing the borate-citrate acid buffering solution, CdTe nanocrystals with high quantum yield (QY >70% at pH range 5.0-8.0) can be conveniently prepared by this method. The influence of parameters such as the pH value of the precursor solution and the molar ratio of Cd(2+) to Na(2)TeO(3) on the QY of CdTe nanocrystals was systematically investigated in our experiments. Under optimal conditions, the QY of CdTe nanocrystals is even high up to 83%. The biological application of luminescent MSA-CdTe to HEK 293 cell imaging was also illustrated.

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(A) The image of MSA-coated CdTe QDs with different sizes under ambient conditions (top) and the corresponding absorption spectra (bottom); (B) The image of the above-mentioned MSA-coated CdTe QDs under an ultraviolet lamp (top) and the corresponding photoluminescence spectra (bottom). The photoluminescence were at a) 493 nm, b) 519 nm, c) 551 nm, d) 589 nm, e) 617 nm, f) 647 nm. These CdTe QDs were synthesized at pH = 7.2.
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pone-0002222-g001: (A) The image of MSA-coated CdTe QDs with different sizes under ambient conditions (top) and the corresponding absorption spectra (bottom); (B) The image of the above-mentioned MSA-coated CdTe QDs under an ultraviolet lamp (top) and the corresponding photoluminescence spectra (bottom). The photoluminescence were at a) 493 nm, b) 519 nm, c) 551 nm, d) 589 nm, e) 617 nm, f) 647 nm. These CdTe QDs were synthesized at pH = 7.2.

Mentions: At the initial stage when NaBH4 powder was added, the clear precursor solution would turn green in tens of seconds, depending on the pH value, the concentration of the precursor solution, and the reaction temperature. Lowering the pH value of the precursor solution or increasing the concentrations of the precursor solution or raising the reaction temperature will accelerate the formation of CdTe NCs. A large amount of bubbles were also found to release from the solution. No luminescence was observed from this crude solution owing to the very small size of the initially formed CdTe NCs. As it was heated to boiling for several minutes, the color of the solution became greener and the weak luminescence was detected. With the prolonging of reflux time, the absorption spectra of CdTe NCs as well as the PL emission spectra shifted to longer wavelengths with increasing size of the CdTe NCs as a consequence of the quantum confinement. The size of the CdTe NCs could be controlled by the duration of reflux and easily monitored by absorption and PL spectra. Figure 1 shows typical evolutions of both absorption (Figure 1A, bottom) and photoluminescence (Figure 1B, bottom) spectra of MSA-stabilized CdTe NCs prepared in aqueous solution. The images of MSA-stabilized CdTe NCs with different sizes under room light conditions (Figure 1A, top) and irradiated under an ultraviolet lamp (Figure 1B, top) are also presented. These samples were prepared in a buffer solution at pH 7.2. The spectra were measured on as-prepared CdTe colloidal solution that was taken from the refluxing reaction mixture at different interval of time. During the refluxing of about 9 h, the emission peaks of CdTe NCs shifted from 493 nm to 647 nm, and the full width at half maximum of the PL peaks increased from 35 nm to 70 nm, which indicated the narrow size distribution of the as-prepared CdTe NCs.


Synthesis and bio-imaging application of highly luminescent mercaptosuccinic acid-coated CdTe nanocrystals.

Ying E, Li D, Guo S, Dong S, Wang J - PLoS ONE (2008)

(A) The image of MSA-coated CdTe QDs with different sizes under ambient conditions (top) and the corresponding absorption spectra (bottom); (B) The image of the above-mentioned MSA-coated CdTe QDs under an ultraviolet lamp (top) and the corresponding photoluminescence spectra (bottom). The photoluminescence were at a) 493 nm, b) 519 nm, c) 551 nm, d) 589 nm, e) 617 nm, f) 647 nm. These CdTe QDs were synthesized at pH = 7.2.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2377334&req=5

pone-0002222-g001: (A) The image of MSA-coated CdTe QDs with different sizes under ambient conditions (top) and the corresponding absorption spectra (bottom); (B) The image of the above-mentioned MSA-coated CdTe QDs under an ultraviolet lamp (top) and the corresponding photoluminescence spectra (bottom). The photoluminescence were at a) 493 nm, b) 519 nm, c) 551 nm, d) 589 nm, e) 617 nm, f) 647 nm. These CdTe QDs were synthesized at pH = 7.2.
Mentions: At the initial stage when NaBH4 powder was added, the clear precursor solution would turn green in tens of seconds, depending on the pH value, the concentration of the precursor solution, and the reaction temperature. Lowering the pH value of the precursor solution or increasing the concentrations of the precursor solution or raising the reaction temperature will accelerate the formation of CdTe NCs. A large amount of bubbles were also found to release from the solution. No luminescence was observed from this crude solution owing to the very small size of the initially formed CdTe NCs. As it was heated to boiling for several minutes, the color of the solution became greener and the weak luminescence was detected. With the prolonging of reflux time, the absorption spectra of CdTe NCs as well as the PL emission spectra shifted to longer wavelengths with increasing size of the CdTe NCs as a consequence of the quantum confinement. The size of the CdTe NCs could be controlled by the duration of reflux and easily monitored by absorption and PL spectra. Figure 1 shows typical evolutions of both absorption (Figure 1A, bottom) and photoluminescence (Figure 1B, bottom) spectra of MSA-stabilized CdTe NCs prepared in aqueous solution. The images of MSA-stabilized CdTe NCs with different sizes under room light conditions (Figure 1A, top) and irradiated under an ultraviolet lamp (Figure 1B, top) are also presented. These samples were prepared in a buffer solution at pH 7.2. The spectra were measured on as-prepared CdTe colloidal solution that was taken from the refluxing reaction mixture at different interval of time. During the refluxing of about 9 h, the emission peaks of CdTe NCs shifted from 493 nm to 647 nm, and the full width at half maximum of the PL peaks increased from 35 nm to 70 nm, which indicated the narrow size distribution of the as-prepared CdTe NCs.

Bottom Line: By selecting mercaptosuccinic acid (MSA) as capping agent and providing the borate-citrate acid buffering solution, CdTe nanocrystals with high quantum yield (QY >70% at pH range 5.0-8.0) can be conveniently prepared by this method.The influence of parameters such as the pH value of the precursor solution and the molar ratio of Cd(2+) to Na(2)TeO(3) on the QY of CdTe nanocrystals was systematically investigated in our experiments.Under optimal conditions, the QY of CdTe nanocrystals is even high up to 83%.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China.

ABSTRACT
Here we present a facile one-pot method to prepare high-quality CdTe nanocrystals in aqueous phase. In contrast to the use of oxygen-sensitive NaHTe or H(2)Te as Te source in the current synthetic methods, we employ more stable sodium tellurite as the Te source for preparing highly luminescent CdTe nanocrystals in aqueous solution. By selecting mercaptosuccinic acid (MSA) as capping agent and providing the borate-citrate acid buffering solution, CdTe nanocrystals with high quantum yield (QY >70% at pH range 5.0-8.0) can be conveniently prepared by this method. The influence of parameters such as the pH value of the precursor solution and the molar ratio of Cd(2+) to Na(2)TeO(3) on the QY of CdTe nanocrystals was systematically investigated in our experiments. Under optimal conditions, the QY of CdTe nanocrystals is even high up to 83%. The biological application of luminescent MSA-CdTe to HEK 293 cell imaging was also illustrated.

Show MeSH