Synthesis of type II/type I CdTe/CdS/ZnS quantum dots and their use in cellular imaging

Green, Mark; Williamson, Peter; Samalova, Marketa; Davis, Jason J.; Brovelli, Sergio; Dobson, Peter J.; Cacialli, Franco

doi:10.1039/b913292a

Cited by 26 publications

(31 citation statements)

References 41 publications

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“…The successful synthesis of CdTe multi-core-shell nanoparticles has engendered the production of material with high florescence intensity, long-term photo stability, and reduced toxicity. The transformation of the CdTe core to multicore-shells using ZnS or ZnSe as the outer shell tends to improve the bio-compatibility of the synthesized heterostructure by limiting the toxic Cd ion’s direct interaction with cells [ 16 , 17 , 18 ]. This affords the usage of the synthesized QDs as optical probes in various imaging studies including deep-tissue cellular imaging applications.…”

Section: Introductionmentioning

confidence: 99%

Rapid Synthesis of Thiol-Co-Capped-CdTe/CdSe/ZnSe Core Shell-Shell Nanoparticles: Their Optical and Structural Morphology

et al. 2021

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CdTe QDs has been demonstrated in many studies to possess good outstanding optical and photo-physical properties. However, it has been established from literature that the toxic Cd2+ that tends to leak out into nearby solutions can be protected by less toxic ZnS or ZnSe shells leading to the synthesis of core-shells and multi-core-shells. Hence, this has allowed the synthesis of CdTe multi-core-shells to have gained much interest. The preparation of most CdTe multi-core-shells reported from various studies usually has a longer reaction time (6–24 h) in reaching their highest emission maxima. The synthesis of CdTe multi-core-shells in this study only took 35 min to obtain a highest emission maximum compared to what has been reported from the literature. CdTe multi-core-shells were synthesized by injecting 7, 14, and 21 mL each of Zn complex solution and Se ions into the reacting mixture containing CdTe core-shells (3 h) at 5 min intervals over a 35 min reaction time. The emission maxima of the MPA-TGA-CdTe multi-core-shells at 21 mL injection was recorded around 625 nm. Therefore, we are reporting the rapid synthesis of five different thiol co-capped CdTe/CdSe/ZnSe multi-core-shell QDs with the highest emission maxima obtained at 35 min reaction time.

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Section: Introductionmentioning

confidence: 99%

Rapid Synthesis of Thiol-Co-Capped-CdTe/CdSe/ZnSe Core Shell-Shell Nanoparticles: Their Optical and Structural Morphology

et al. 2021

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“…As a result, a ZnS shell improves chemical stability as well as the optical properties of NCs. 7 On this basis, a preliminary study was published by Green et al using the aqueous overgrowth of a ZnS shell around CdTe/CdS NCs in 24 h. 8 Very recently, this strategy was further improved by Zhu and coworkers with microwave-assisted irradiation of CdSeTe (small) /CdS (thick) CS NCs and further deposition of a very thin ZnS shell. 9 As a result, QY values were increased by a further $4% to 63% with the overgrowth of a ZnS shell and growth rates were remarkably accelerated in the aqueous phase.…”

Section: Introductionmentioning

confidence: 99%

One-pot aqueous synthesis of highly strained CdTe/CdS/ZnS nanocrystals and their interactions with cells

et al. 2015

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In this work, a very simple one-pot synthetic approach was developed to generate aqueous CdTe/CdS/ZnS type-II/type-I red-emitting nanocrystals (NCs). Strain-induced optical properties of CdTe/CdS particles having core (small) /shell (thick) structure with a maximum quantum yield (QY max ) $ 57% were further improved with the overgrowth of a ZnS shell, resulting in a core (small) /shell (thick) /shell (small) structure (QY max $ 64%). The spectral properties were tuned further to the near-infrared region as the ZnS shell grew in thickness. X-ray powder diffraction (XRD) analysis and high-resolution transmission electron microscope (HRTEM) images showed the crystalline structure of NCs proving the epitaxial growth of ZnS without crystalline defects. Under continuous UV-irradiation for 5 h, the NCs did not exhibit any photodegradation but instead displayed a photo-annealing process. These extremely photostable NCs were further characterized in terms of their cytotoxicity and their cell labeling performances. The presence of a ZnS shell was found to reduce the toxicity of the CdTe/CdS NCs. Furthermore, aptamer-conjugated NCs were successfully utilized in targeted cell imaging. Promisingly, the aptamer-NCs bioconjugates were internalized by A549 cells within 2 hours of incubation and retained their fluorescence even after 24 hours of internalization.

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“…al 39 Initial cytotoxicity studies were conducted using QDs coated with 2.5% polymer diluted in PBS as this was the highest polymer concentration that showed biocompatibility to HepG2 cells at 24 hours. For later studies and to determine the optimal polymer concentration for QD coating we used three different polymer preparations to coat the QDs.…”

Section: Methods Of Qd Coatingmentioning

confidence: 99%

Novel POSS–PCU Nanocomposite Material as a Biocompatible Coating for Quantum Dots

et al. 2015

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Quantum dots (QDs) are fluorescent nanoparticles with unique photophysical properties that enable them to potentially replace traditional organic dyes and fluorescent proteins in various bioimaging applications. However, the inherent toxicity of their cores based on cadmium salts limits their widespread biomedical use. We have developed a novel nanocomposite polymer emulsion based on polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) that can be used to coat quantum dots to nullify their toxicity and enhance photostability. Here we report the synthesis and characterization of a novel POSS-PCU nanocomposite polymer emulsion and describe its application for coating QDs for biological application. The polymer was synthesized by a process of emulsion polymerization and formed stable micelles of ∼33 nm in diameter. CdTe/CdS/ZnS QDs were efficiently stabilized by the polymer emulsion through encapsulation within the polymer micelles. Characterization studies showed no significant change in the unique photophysical properties of QDs after coating. The polymer was biocompatible to HepG2, HUVECs, and mouse skeletal muscle cells at 2.5% after 24 h exposure on in vitro testing. Polymer encapsulated QDs showed enhanced photostability on exposure to high degrees of UV irradiation and air as well as significantly reduced cytotoxicity on exposure to HepG2 cells at 30 μg/mL for 24 h. We have therefore concluded that the POSS-PCU polymer emulsion has the potential to make a biocompatible and photostable coating for QDs enabling a host of biomedical applications to take this technology to the next level.

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Synthesis of type II/type I CdTe/CdS/ZnS quantum dots and their use in cellular imaging

Abstract: Water-soluble, stable quantum dots consisting of a CdTe core with shells of CdS and ZnS have been prepared using a simple successive injection of precursors in one-pot technique. The particles exhibited type II behaviour and were successfully used in imaging HeLa cells.

Cited by 26 publications

References 41 publications

Rapid Synthesis of Thiol-Co-Capped-CdTe/CdSe/ZnSe Core Shell-Shell Nanoparticles: Their Optical and Structural Morphology

Rapid Synthesis of Thiol-Co-Capped-CdTe/CdSe/ZnSe Core Shell-Shell Nanoparticles: Their Optical and Structural Morphology

One-pot aqueous synthesis of highly strained CdTe/CdS/ZnS nanocrystals and their interactions with cells

Novel POSS–PCU Nanocomposite Material as a Biocompatible Coating for Quantum Dots

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