L-Cysteine capped CdTe-CdS core-shell quantum dots: preparation, characterization and immuno-labeling of HeLa cells (original) (raw)
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Journal of Luminescence, 2012
CdTe/CdS/ZnS core-shell-shell quantum dots (QDs) were synthesized in aqueous solution via waterbathing combined hydrothermal method using L-cysteine as a stabilizer. The present method features markedly reduced synthesis time, higher fluorescent intensity and lower cytotoxicity of the QDs. Structural and spectroscopic properties of core-shell-shell QDs are well characterized by absorption and fluorescence spectroscopy, X-ray diffraction, transmission electron microscopy, and fourier transform infrared spectroscopy. Both CdS and ZnS shells were capped on the CdTe core and the fluorescence was greatly enhanced by the ZnS coating. The ternary QDs conjugated with transferrins were successfully employed for the biolabeling and fluorescent imaging of HeLa cells. Cytotoxicity evaluation shows that CdTe/CdS/ZnS was less toxic for cells than CdTe and CdTe/CdS due to the presence of a ZnS coating on surface, which inhibited the release of cadmium ions.
Water-soluble, mercaptosuccinic acid (MSA)-capped CdTe/CdS/ZnS core/double shell quantum dots (QDs) were prepared by successive growth of CdS and ZnS shells on the as-synthesized CdTe/CdS thin core/shell quantum dots. The formation of core/double shell structured QDs was investigated by ultraviolet-visible (UV–Vis) absorption and photoluminescence (PL) spectroscopy, PL decay studies, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The core/double shell QDs exhibited good photoluminescence quantum yield (PLQY) which is 70% higher than that of the parent core/shell QDs, and they are stable for months. The average particle size of the core/double shell QDs was ∼3 nm as calculated from the transmission electron microscope (TEM) images. The cytotoxicity of the QDs was evaluated on a variety of cancer cells such as HeLa, MCF-7, A549, and normal Vero cells by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell viability assay. The results showed that core/double shell QDs were less toxic to the cells when compared to the parent core/shell QDs. MCF-7 cells showed proliferation on incubation with QDs, and this is attributed to the metalloestrogenic activity of cadmium ions released from QDs. The core/double shell CdTe/CdS/ZnS (CSS) QDs were conjugated with transferrin and successfully employed for the biolabeling and fluorescent imaging of HeLa cells. These core/double shell QDs are highly promising fluorescent probe for cancer cell labeling and imaging applications.
Highly fluorescent CdTe quantum dots with reduced cytotoxicity-A Robust biomarker
Sensing and Bio-Sensing Research, 2015
L-Cysteine (Cys) capped CdTe quantum dots (CdTe@Cys QDs) were successfully synthesized in an aqueous medium. The synthesized CdTe@Cys samples were analyzed using Fourier transform infrared (FT-IR) spectroscopy, fluorescence (FL) spectroscopy, transmission electron microscopy (TEM), confocal microscopy and subsequently subjected to the antibacterial test. Systematic investigations were carried out for the determination of optimal conditions namely the ratios of Cd:Te, CdTe:Cys, pH value and the chemical stability of CdTe@Cys. Moreover, the reactivation of FL intensity in the CdTe@Cys sample was done easily by the addendum of Cys. The introduction of additional cysteine to the CdTe@Cys QDs sample showed an enhancement in terms of the FL intensity and stability along with the reduced antibacterial activity. This was further confirmed through Thiazolyl blue tetrazolium bromide (MTT) assays. Both the result of the bio-stability tests namely the antibacterial test and MTT assay displayed similarities between the externally added Cys and cytotoxicity of the bacteria and human HeLa cancer cell lines. Confocal microscopic images were captured for the CdTe@Cys conjugated Escherichia coli.
Core-shell CdS/Cd(OH)2 quantum dots: synthesis and bioconjugation to target red cells antigens
Journal of Microscopy, 2005
We report a new and efficient methodology of labelling red blood cells, in order to investigate the expression of anti-A antigen, employing luminescent semiconductor nanocrystals. Highly luminescent and stable core-shell cadmium sulphide/ cadmium hydroxide [CdS/CdS(OH) 2 ] colloidal particles were obtained in the nanometre size range. The surface of these particles was characterized by using a monoclonal anti-A antibody via a one-step glutaraldehyde cross-linking procedure, followed by conjugation of the particles to red cells of blood groups A + , and O + . Laser scanning confocal microscopy images indicated that after conjugation for 30 min, A + and erythrocytes presented different patterns of dual bright emission whereas the O + group cells showed no emission. We suggest that this labelling procedure may be applied as a quantitative tool to investigate the distribution and expression of alloantigen in red blood cells.
Journal of Nanoscience and Nanotechnology, 2019
Quantum dots have now become the most important candidates and widely exploited as promising architectures for use as diagnostic and imaging agents in biomedicine and as semiconductors in the electronics industry. This article emphasizes on the aqueous synthesis of water soluble CdSe/CdS/ZnS core/shell/shell quantum dots with L-cysteine and mercaptopropionic acid as capping agent and their observed properties have been compared. The biocompatibility of the assynthesized quantum dots have also been analyzed through the cytotoxicity study using MTT assay. The structural, morphological and optical properties of these quantum dots have been examined through X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), UV-Visible absorption spectroscopy (UV-Vis) and Photoluminescence spectroscopy (PL). The capping of L-cysteine and mercaptopropionic acid on the quantum dots has been confirmed from Fourier transform infrared spectroscopy (FTIR). XRD results demonstrat...
Synthesis and Characterization of Aqueous Carboxyl-Capped CdS Quantum Dots for Bioapplications
Industrial & Engineering Chemistry Research, 2007
A direct and environmentally friendly synthesis method was developed to produce aqueous CdS quantum dots (QDs) at room temperature. The transmission electron microscopy (TEM) and X-ray diffraction (XRD) results showed the small size and the cubic zinc blende structure of the nanocrystals. The quantum yield was comparable to that of the commercial core-shell QDs. With 3-mercaptopropionic acid (MPA) as the capping molecule, the feasibility of using the aqueous CdS QDs as imaging tool was demonstrated with Salmonella typhimurium cells. The photoluminescence (PL) properties of the present aqueous CdS QDs can be optimized by adjusting various processing parameters. The emission was due to trap states and was related to the dispersion condition. In particular, with higher pH and MPA/Cd ratio of 2, the QDs exhibited stronger emission. The temperature-and concentration-dependent properties of QDs resulted from the intrinsic interactions between nanoparticles. The aqueous CdS QDs displayed long lifetime of 12 h under UV light and excellent stability in DI water, PBS, and cytosol for more than 26 days. The ease of processing and good PL properties of the aqueous CdS QDs provide a practical and economical approach for single-target imaging application.
Application of Antibody-Conjugated CdSe/MSA Quantum Dots on Immunohistochemistry
SSR Institute of International Journal of Life Sciences, 2020
Background: Quantum dots (QDs) are recently conjugated to antibody for using in biological labeling applications. In previous studies, we developed CdSe/MSA QDs, which were coated with protein A/G (pA/G) for antibody conjugation, and evaluated their cell staining application. Here, we expanded their applications into immunohistochemistry (IHC) by investigating their storage time by accelerated heat aging method, and comparing them with FITC in sample labeling. Methods: Cytokeratin 6A (KRT6A) in animal skin tissue section were stained by pA/G-coated QDs conjugated to anti-KRT6A antibody and TF-1 human erythroleukemia cells were stained by pA/G-coated QDs conjugated to anti-CD34 antibody. Results: The results indicated that our pA/G-coated QDs effectively stained KRT6A in epidermis of skin tissue section when they were probed with specific antibody. Besides, pA/G-coated QDs still maintained their labeling ability in cell staining and IHC formats after 12-month storage at 4 o C. In comparison with FITC (relatively almost the same emission fluorophore), our QDs showed a significantly stronger fluorescent signal. Conclusion: In conclusion, these results indicated that our pA/G-coated QDs were potentially fluorescent nanomaterials and could be applied in a wide range of biological labeling applications.
CdTe quantum dots for an application in the life sciences
Advances in Natural Sciences: Nanoscience and Nanotechnology, 2010
This report highlights the results of the preparation of semiconductor CdTe quantum dots (QDs) in the aqueous phase. The small size of a few nm and a very high luminescence quantum yield exceeding 60% of these materials make them promisingly applicable to bio-medicine labeling. Their strong, two-photon excitation luminescence is also a good characteristic for biolabeling without interference with the cell fluorescence. The primary results for the pH-sensitive CdTe QDs are presented in that fluorescence of CdTe QDs was used as a proton sensor to detect proton flux driven by adenosine triphosphate (ATP) synthesis in chromatophores. In other words, these QDs could work as pH-sensitive detectors. Therefore, the system of CdTe QDs on chromatophores prepared from the cells of Rhodospirillum rubrum and the antibodies against the beta-subunit of F0F1-ATPase could be a sensitive detector for the avian influenza virus subtype A/H5N1.
Colloids and Surfaces B: Biointerfaces, 2012
We have successfully synthesized GSH and TGA co-capped CdTe quantum dots (QDs) with good biological compatibility and high fluorescence intensity. The effects of different reaction time, temperature, pH value, ligand concentration and the molar ratio of GSH/TGA were carefully investigated to optimize the synthesis condition. The optical properties of as-prepared CdTe QDs were studied by UV-visible absorption spectrum and fluorescence spectrum, meanwhile their structure and morphology were characterized using transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR) and X-ray powder diffraction (XRD). Compared with the CdTe QDs that are single-capped with either GSH or TGA, the GSH-TGA co-capped CdTe QDs demonstrated significantly improved fluorescence intensity and optical stability. In addition, GSH-TGA co-capped CdTe QDs were conjugated to amonoclonal antibody ND-1. The GSH-TGA co-capped CdTe QDs-antibody probe was successfully used to label colorectal cancer cells, CCL187, in vitro.
Biofunctional quantum dots as fluorescence probe for cell-specific targeting
Colloids and Surfaces B: Biointerfaces, 2014
We describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Antihuman epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, and gel electrophoresis. TGA-QDs and TGA-QDs/anti-HER2 were incubated with cells to examine cytotoxicity, targeting efficiency, and cellular localization. The cytotoxicity of particles was measured using an MTT assay and the no observable adverse effect concentration (NOAEC), 50% inhibitory concentration (IC 50 ), and total lethal concentration (TLC) were calculated. To evaluate localization and targeting efficiency of TGA-QDs with or without antibodies, fluorescence microscopy and flow cytometry were performed. Our results indicate that antibody-conjugated TGA-QDs are well-suited for targeted cellular imaging studies.