Synthesis of Deep-Red-Emitting CdSe Quantum Dots and General Non-Inverse-Square Behavior of Quantum Confinement in CdSe Quantum Dots

Wang, Qiangbin; Seo, Dong Kyun

doi:10.1021/cm061051j

Cited by 58 publications

(42 citation statements)

References 30 publications

(64 reference statements)

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“…[13,14] The CdSe@ ZnS core-shell QDs with thiolated DNA as the capping ligand were prepared as follows. In a typical reaction, P 2 S 5 (0.01 mmol), mercaptopropyl acid (MPA; 10 mL), and butylamine (10 mL) were heated at 110 8C for 20 min in DMSO (1.5 mL) in a sealed vial to dissolve the sulfide.…”

Section: Methodsmentioning

confidence: 99%

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Quantum Dot Bioconjugation during Core–Shell Synthesis

Wang

Liu

et al. 2007

Angew Chem Int Ed

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Quantum dots (QDs) [1] have attracted tremendous interest in biological applications, such as bioimaging, [2,3] biolabeling, [4,5] and biosensing, [6,7] because of their advantages over organic fluorophores at high quantum yield (QY), size-tunable narrow emission, photostability, etc.[8] Many of the above applications entail water-soluble and biomolecule-conjugated QDs. To date, various strategies have been developed to obtain QD bioconjugates, either by cross-linking chemistry, [2,3,5] biotin-avidin interactions, [7,8] or ligand-exchange methods, [9,10] but these commonly require multiple steps to obtain the final products. Herein, we present a simple and robust one-step method for creating stable, water-soluble QD-biomolecule conjugates. We demonstrate the successful implementation of this strategy by using DNA molecules as a model system, but expect this could also be extended to other types of biomolecules.This new strategy was devised so that direct capping of QDs with thiolated DNA oligonucleotides could be achieved during the formation of core-shell QDs. This in situ functionalization of QDs with DNA avoids the cross-linking chemistry or the second-step ligand exchange after core-shell formation. We demonstrate that a high DNA density on the QD surface is achieved and the high QY and stability of the QDs are preserved. Such prepared DNA-capped QDs could serve as excellent candidates for fabrication of biosensors and nanodevices.[11]The process of QD functionalization with DNA is illustrated in Figure 1 a. The starting oleylamine-capped CdSe QDs were prepared by our previously reported lowtemperature synthesis method. [12][13][14] Coating of the CdSe core with a ZnS shell and capping of the surface with thiolated DNA oligonucleotides are achieved in a single-step one-pot reaction by mixing the oleylamine-capped QD core with Zn 2+ , S 2À, and thiolated DNA all dissolved in dimethyl sulfoxide (DMSO).We synthesized two different CdSe@ZnS core-shell QDs with the surface capped with different DNA strands (Figure 2): green QD (l Em = 548 nm) capped with a capture strand C1, denoted G-QD-C1, and red QD (l Em = 617 nm) capped with a capture strand C2, denoted R-QD-C2. These QDs are purified and finally dispersed in 0.5 Tris/acetic acid/ EDTA (TAE) Mg 2+ buffer solution (see Experimental Section for details).The PL spectra of the QDs before and after the ZnS shell growth/surface capping are shown in Figure 1 b. For measurement of the spectra, the oleylamine-capped CdSe QDs were dispersed in hexane solution and the obtained DNA-capped CdSe@ZnS core-shell QDs were dispersed in 0.5 TAE Mg 2+ buffer solution. As we demonstrated, [5,14] there were negligible spectral shifts before and after shell formation. The QYs of DNA-capped CdSe@ZnS QDs are significantly increased from those of the QD cores: 8.6 to 41.3 % for the green QD and 4.4 to 21.7 % for the red QD.[15] It is well-known that passivating CdSe core particles with a larger-bandgap layer of ZnS increases the QYs of QDs. [5,16,17] The significant increase in the QY...

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Section: Methodsmentioning

confidence: 99%

“…The starting oleylamine-capped CdSe QDs were prepared by our previously reported lowtemperature synthesis method. [12][13][14] Coating of the CdSe core with a ZnS shell and capping of the surface with thiolated DNA oligonucleotides are achieved in a single-step one-pot reaction by mixing the oleylamine-capped QD core with Zn 2+ , S …”

mentioning

confidence: 99%

Quantum Dot Bioconjugation during Core–Shell Synthesis

Wang

Liu

et al. 2007

Angew Chem Int Ed

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“…9,10 These QDs absorb in the visible spectrum from the blue to the red with sizes d = 2.5, 4, and 9.7 nm and were kept in stock as suspensions in cyclohexane. They are referred to as G, Y, and R, respectively, and their apparent diameters d have been checked by transmission electron microscopy ͑TEM͒ as shown in Fig.…”

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confidence: 99%

“…determined for all the CdSe QDs luminescent in red to blue visible light. 10 CW PL spectra of the QDs in suspensions are reported in Fig. 1͑b͒.…”

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confidence: 99%

Mapping emissive channels of quantum dots: Influence of size and environment on energy transfer in the time domain

Faulques

Massuyeau

Wang

et al. 2010

Applied Physics Letters

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International audienceIn the quantum confinement regime, the time-resolved photoluminescence mapping of CdSe nanocrystals reveals unusual size-dependent characteristics in solute or solid-state environments. The former case typifies long-lived intradot exciton recombinations, while in the latter energy-dependent Kohlrausch relaxations quench luminescence via interdot energy transfer. The observed energy transfer rate increases for larger size (1.5×108 s−1 for d = 2.5 nm and 6.4×108 s−1 for d = 10 nm)

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“…For example, microwave techniques have been used to prepare a wide range of materials including nanocrystalline composite solid electrolyte like Bi 2 O 3 -HfO 2 -Y 2 O 3 by microwave plasma [52] deep-red-emitting CdSe quantum dots [53] carbon-coated core shell structured copper and nickel nanoparticles in a ionic liquid [54] Bi 2 Se 3 nanosheets [55] Au@Ag core-shell nanoparticles [56]. Overall, while microwave assisted syntheses of quantum dots and other nanomaterials have been reported [57,58] including ZnSe(S) quantum dots synthesis using microwave heating [59] in comparison to the strategies reported herein, these procedures often result in QDs of varying morphologies or aggregated crystals with comparably poor luminescent properties, such as broad emission bands.…”

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confidence: 99%

Highly luminescent nanostructures of CdS and ZnS prepared by microwaves heating: effect of sulphide concentration

Ortíz¹,

Gómez²,

Martínez³

et al. 2010

Phys. Status Solidi (c)

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Nearly monodisperse and highly luminescent ZnS and CdS NPs were obtained by microwave irradiation. The ZnS and CdS NPs solutions were prepared by adding freshly prepared ZnSO4 or CdSO4 solution to a thioacetamide solution at pH 8 in the presence of sodium citrate in solution used as stabilizer. The precursors concentration were such that the sulphide ion concentrations were 3 × 10–2 M, 6 × 10–2 M and 8 × 10–2 M, for each of these [S] concentrations the [Zn] or [Cd] content were fixed at 3 × 10–2 M. NPs were prepared under microwave irradiation for 1 min at 905 W of power. The NPs samples were taken when the temperature descended to ambient temperature for further analysis. Effect of concentration of Cd and Zn ions were studied in the luminescence property. RXD, AFM, TEM and UV‐Vis were used too as analytical equipment for characterization. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Synthesis of Deep-Red-Emitting CdSe Quantum Dots and General Non-Inverse-Square Behavior of Quantum Confinement in CdSe Quantum Dots

Cited by 58 publications

References 30 publications

Quantum Dot Bioconjugation during Core–Shell Synthesis

Quantum Dot Bioconjugation during Core–Shell Synthesis

Mapping emissive channels of quantum dots: Influence of size and environment on energy transfer in the time domain

Highly luminescent nanostructures of CdS and ZnS prepared by microwaves heating: effect of sulphide concentration

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