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

Abstract

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.

Evaluation of CdTe/CdS/ZnS core/shell/shell quantum dot toxicity on three-dimensional spheroid cultures

“…38 NP-induced hormesis was attributed to increasing ROS levels with low-doses, giving rise to cell activities to suppress the imbalance, thus causing an increase in metabolic activities. 19 Regarding in vivo Qdot-induced toxicity analysis; Hauck et al reported that CdSe/ZnS core/shell Qdot did not show any significant toxicity in healthy Sprague-Dawley rats. 40,41 Though, CTB assay for 2D culture and ATP assay for 3D cultures didn't demonstrate similar patterns.…”

“…19 The developed CSS Qdots hold a great potential for cellular imaging studies to owing near-infrared emission, which will give them an advantage to be monitored in thick and highly scattering 3D tissue samples. One-pot aqueous synthesis of near-infrared emitting CdTe/CdS/ZnS core (small) /shell (thick) /shell (small) CSS Qdots with high quantum yields (~ 64%) and impressive stability against photobleaching was recently reported in our previous study.…”

“…One-pot aqueous synthesis of near-infrared emitting CdTe/CdS/ZnS core (small) /shell (thick) /shell (small) CSS Qdots with high quantum yields (~ 64%) and impressive stability against photobleaching was recently reported in our previous study. 19 For that reason, hAD-MSCs were chosen as a suitable candidate to investigate Qdot-induced cytotoxicity. 20 As a model system, we utilized human adipose-derived mesenchymal stem cells (hAD-MSCs) spheroid cultures as they are considered to be a promising candidate for cell therapy.…”

Aptamer-modified polymer nanoparticles for targeted drug delivery

“…We have recently used aptamer S15-functionalized quantum dots for specific staining of A549 cells [33]. We also have compared the binding of S15 to A549 cells in comparison to a random oligonucleotide as a negative control.…”

A facile route to aqueous Ag:ZnCdS and Ag:ZnCdSeS quantum dots: Pure emission color tunable over entire visible spectrum

“…Jing et al reported aqueous manganese-doped core-shell CdTe/ZnS QDs with strong fluorescence and high relaxivity [33]. More recently, a very simple one-pot synthetic approach was developed to generate aqueous CdTe/CdS/ZnS type-II/type-I red-emitting QDs, and strain-induced optical properties of CdTe/ CdS QDs with a maximum PL QY of $57% were further improved with the overgrowth of a ZnS shell, resulting in a core/shell/shell structure of $64% PL QY [34]. However, a versatile aqueous sulfide precursor with high reactivity for metal chalcogenide QDs cannot be obtained because S powder is hard to be reduced by NaBH 4 at room temperature.…”