Iridium-complex modified CdSe/ZnS quantum dots; a conceptual design for bifunctionality toward imaging and photosensitization. Chem Commun 6:615-617

Department of Chemistry, National Tsing Hua University, Hsin-chu-hsien, Taiwan, Taiwan
Chemical Communications (Impact Factor: 6.83). 03/2006; 1(6):615-7. DOI: 10.1039/b517368j
Source: PubMed


We report the design and synthesis of Ir-complex functionalized CdSe/ZnS quantum dots (QDs), in which the QD plays a key role in imaging, while the Ir-complex acts as a sensitizer to produce singlet oxygen; this conceptual design presents a novel scheme in both bio-imaging and photodynamic therapy.

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Available from: Yun Chi, Feb 27, 2015
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    • "Still, the cytotoxicity and solubility in water of Cdbased QDs (despite extended efforts to modify their surface) remain a significant concern. In this regard, Hsiech et al. overcoated CdSe cores with ZnS, being then attached to a cyclometalated Ir complex-type sensitizer (Hsieh et al. 2006). Although the 1 O 2 QY in benzene was improved, it was the Ir complex that was directly excited instead of the QDs. "
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    ABSTRACT: We report here the versatility of Mn-doped ZnS quantum dots (ZnS:Mn QDs) synthesized in aqueous medium for generating reactive oxygen species and for detecting cells. Our experiments provide evidence leading to the elimination of Cd-based cores in CdSe/ZnS systems by substitution of Mn-doped ZnS. Advanced electron microscopy, X-ray diffraction, and optical spectroscopy were applied to elucidate the formation, morphology, and dispersion of the products. We study for the first time the ability of ZnS:Mn QDs to act as immobilizing agents for Tyrosinase (Tyr) enzyme. It was found that ZnS:Mn QDs show no deactivation of Tyr enzyme, which efficiently catalyzed the hydrogen peroxide (H2O2) oxidation and its eventual reduction (-0.063 V vs. Ag/AgCl) on the biosensor surface. The biosensor showed a linear response in the range of 12 μmol/L-0.1 mmol/L at low operation potential. Our observations are explained in terms of a catalase-cycled kinetic mechanism based on the binding of H2O2 to the axial position of one of the active copper sites of the oxy-Tyr during the catalase cycle to produce deoxy-Tyr. A singlet oxygen quantum yield of 0.62 in buffer and 0.54 in water was found when ZnS:Mn QDs were employed as a photosensitizer in the presence of a chemical scavenger and a standard dye. These results are consistent with a chemical trapping energy transfer mechanism. Our results also indicate that ZnS:Mn QDs are well tolerated by HeLa Cells reaching cell viabilities as high as 88 % at 300 µg/mL of QDs for 24 h of incubation. The ability of ZnS:Mn QDs as luminescent nanoprobes for bioimaging is also discussed. Graphical abstract:
    Full-text · Article · Dec 2015 · Journal of Nanoparticle Research
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    • "Among other nanomaterials, a subset of engineered nanocrystals known as semiconductor quantum dots (QDs) seem to be promising candidates for clinical purposes [3]. Nanomaterial formulations with quantum dots carry convincing attributes for new or advanced uses in several medical applications including photodynamic therapy [4] [5], drug delivery [6] [7], and versatile imaging purposes [8e12]. Based on their outstanding tunable optophysical properties, they have attracted the attention of biomedical researchers and clinicians interested in new tools for diagnostics and targeting of specific sites in the body. "
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    ABSTRACT: The increasing interest in biomedical applications of semiconductor quantum dots (QDs) is closely linked to the use of surface modifications to target specific sites of the body. The immense surface area of vascular endothelium is a possible interaction platform with systemically administered QDs. Therefore, the aim of this study was to investigate the microvascular distribution of neutral, cationic, and anionic QDs in vivo. QDs with carboxyl-, amine- and polyethylene glycol surface coatings were injected into the blood circulation of mice. In vivo microscopy of the cremaster muscle, two-photon microscopy of skeletal and heart muscle, as well as quantitative fluorescence measurements of blood, excreta, and tissue samples were performed. Transmission electron microscopy was used to detect QDs at the cellular level. The in vitro association of QDs with cultured endothelial cells was investigated by flow cytometry and confocal microscopy. Anionic QDs exhibited a very low residence time in the blood stream, preferably accumulated in organs with a prominent mononuclear phagocytic component, but were also found in other tissues with low phagocytic properties where they were predominantly associated with capillary endothelium. This deposition behavior was identified as a new, phagocyte-independent principle contributing to the rapid clearance of anionic QDs from the circulation.
    Full-text · Article · Sep 2010 · Biomaterials
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    • "One of them, we herein demonstrate a novel methods for gene-introduction using nanocrystal Quamtum dots (QDs). In recent years, nanobiotechnology has been widely expected to apply QDs to the fields of molecular biology [25] [26] [27], experimental medicine [28] [29] [30] [31] [32] and clinical medicine [33] [34] [35] [36] [37] [38] [39], due to their high photostability. The attached molecules on QDs significantly regulate the intracellular behavior of QDs themselves. "
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    ABSTRACT: Gene therapy is an attractive approach to supplement a deficient gene function. Although there has been some success with specific gene delivery using various methods including viral vectors and liposomes, most of these methods have a limited efficiency or also carry a risk for oncogenesis. Fluorescent nanoparticles, such as nanocrystal quantum dots (QDs), have potential to be applied to molecular biology and bioimaging, since some nanocrystals emit higher and longer lasting fluorescence than conventional organic probes do. We herein report that quantum dots (QDs) conjugated with nuclear localizing signal peptides (NLSP) successfully introduced the gene-fragments with promoter elements, which promoted the expression of the enhanced green fluorescent protein (eGFP) gene in mammalian cells. The expression of eGFP protein was observed when the QD/geneconstruct was added to the culture media. The gene-expression efficiency varied depending on multiple factors around QDs, such as 1) the reading direction of gene fragments, 2) the quantity of gene fragments attached on the surface of QD-constructs, 3) the surface electronic charges varied according to the structure of QD/gene-constructs, and 4) the particle size of QD/gene complex varied according to the structure and amounts of gene fragments. Using this QD/geneconstruct system, eGFP protein could be detected 28 days after the gene-introduction whereas the fluorescence of QDs was disappeared. This system therefore provides another method for the intracellular delivery of gene-fragments without using either viral vectors or specific liposomes. These results suggest that inappropriate treatment and disposal of QDs may still have risks to the environmental pollution including human health under certain conditions. Here we propose the further research for the immune and physiological responses in not only immune cells but also other cells, in order to clear the effect of all other nanoscale products as well as nanocrystal QDs.
    Full-text · Article · Feb 2009 · Proceedings of SPIE - The International Society for Optical Engineering
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