Article

CdTe nanoparticles display tropism to core histones and histone-rich cell organelles.

Department of Clinical Medicine, Trinity College Dublin, Dublin 2, Ireland.
Small (Impact Factor: 7.82). 11/2008; 4(11):2006-15. DOI: 10.1002/smll.200800088
Source: PubMed

ABSTRACT The disclosure of the mechanisms of nanoparticle interaction with specific intracellular targets represents one of the key tasks in nanobiology. Unmodified luminescent semiconductor nanoparticles, or quantum dots (QDs), are capable of a strikingly rapid accumulation in the nuclei and nucleoli of living human cells, driven by processes of yet unknown nature. Here, it is hypothesized that such a strong tropism of QDs could be mediated by charge-related properties of the macromolecules presented in the nuclear compartments. As the complex microenvironment encountered by the QDs in the nuclei and nucleoli of live cells is primarily presented by proteins and other biopolymers, such as DNA and RNA, the model of human phagocytic cell line THP1, nuclear lysates, purified protein, and nucleic acid solutions is utilized to investigate the interactions of the QDs with these most abundant classes of intranuclear macromolecules. Using a combination of advanced technological approaches, including live cell confocal microscopy, fluorescent lifetime imaging (FLIM), spectroscopic methods, and zeta potential measurements, it is demonstrated that unmodified CdTe QDs preferentially bind to the positively charged core histone proteins as opposed to the DNA or RNA, resulting in a dramatic shift off the absorption band, and a red shift and decrease in the pholuminescence (PL) intensity of the QDs. FLIM imaging of the QDs demonstrates an increased formation of QD/protein aggregates in the presence of core histones, with a resulting significant reduction in the PL lifetime. FLIM technology for the first time reveals that the localization of negatively charged QDs to their ultimate nuclear and nucleolar destinations dramatically affects the QDs' photoluminescence lifetimes, and offers thereby a sensitive readout for physical interactions between QDs and their intracellular macromolecular targets. These findings strongly suggest that charge-mediated QD/histone interactions could provide the basis for QD nuclear localization downstream of intracellular transport mechanisms.

0 Bookmarks
 · 
141 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The use of nanoparticles (NPs) has improved the quality of many industrial, pharmaceutical, and medical products. Increased surface reactivity, a major reason for the positive effects of NPs, may, on the other hand, also cause adverse biological effects. Almost all non-biodegradable NPs cause cytotoxic effects but employ quite different modes of action. The relation of biodegradable or loaded NPs to cytotoxic mechanism is more difficult to identify because effects may by caused by the particles or degradation products thereof. This review introduces problems of NPs in conventional cytotoxicity testing (changes of particle parameters in biological fluids, cellular dose, cell line and assay selection). Generation of reactive oxygen and nitrogen species by NPs and of metal ions due to dissolution of the NPs is discussed as a cause for cytotoxicity. The effects of NPs on plasma membrane, mitochondria, lysosomes, nucleus, and intracellular proteins as cellular targets for cytotoxicity are summarized. The comparison of the numerous studies on the mechanism of cellular effects shows that, although some common targets have been identified, other effects are unique for particular NPs or groups of NPs. While titanium dioxide NPs appear to act mainly by generation of reactive oxygen and nitrogen species, biological effects of silver and iron oxide are caused by both reactive species and free metal ions. NPs lacking heavy metals, such as carbon nanotubes and polystyrene particles, interfere with cell metabolism mainly by binding to macromolecules.
    Current Drug Metabolism 11/2013; 14(9):976-88. · 4.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work heparin-gelatine multi-layered cadmium telluride quantum dots (QDgel/hep) were synthesised using a novel 'one-pot' method. The QDs produced were characterised using various spectroscopic and physiochemical techniques. Suitable QDs were then selected and compared to thioglycolic acid stabilised quantum dots (QDTGA) and gelatine coated quantum dots (QDgel) for utilisation in in vitro imaging experiments on live and fixed permeabilised THP-1, A549 and Caco-2 cell lines. Exposure of live THP-1 cells to QDgel/hep resulted in localisation of the QDs to the nucleus of the cells. QDgel/hep show affinity for the nuclear compartment of fixed permeabilised THP-1 and A549 cells but remain confined to cytoplasm of fixed permeabilised Caco-2 cells. It is postulated that heparin binding to the CD11b receptor facilitates the internalisation of the QDs into the nucleus of THP-1 cells. In addition, the heparin layer may reduce the unfavourable thrombogenic nature of quantum dots observed in vivo.
    Nanomedicine: nanotechnology, biology, and medicine 05/2014; · 6.93 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background The rapid expansion of manufacturing and use of nano-sized materials fuels the demand for fast and reliable assays to identify their potential hazardous properties and underlying mechanisms. The ToxTracker assay is a recently developed mechanism-based reporter assay based on mouse embryonic stem (mES) cells that uses GFP-tagged biomarkers for detection of DNA damage, oxidative stress and general cellular stress upon exposure. Here, we evaluated the ability of the ToxTracker assay to identify the hazardous properties and underlying mechanisms of a panel of metal oxide- and silver nanoparticles (NPs) as well as additional non-metallic materials (diesel, carbon nanotubes and quartz).Methods The metal oxide- and silver nanoparticles were characterized in terms of agglomeration and ion release in cell medium (using photon cross correlation spectroscopy and inductively coupled plasma with optical emission spectroscopy, respectively) as well as acellular ROS production (DCFH-DA assay). Cellular uptake was investigated by means of transmission electron microscopy. GFP reporter induction and cytotoxicity of the NPs was simultaneously determined using flow cytometry, and genotoxicity was further tested using conventional assays (comet assay, ¿-H2AX and RAD51 foci formation).ResultsWe show that the reporter cells were able to take up nanoparticles and, furthermore, that exposure to CuO, NiO and ZnO nanoparticles as well as to quartz resulted in activation of the oxidative stress reporter, although only at high cytotoxicity for ZnO. NiO NPs activated additionally a p53-associated cellular stress response, indicating additional reactive properties. Conventional assays for genotoxicity assessment confirmed the response observed in the ToxTracker assay. We show for CuO NPs that the induction of oxidative stress is likely the consequence of released Cu ions whereas the effect by NiO was related to the particles per se. The DNA replication stress-induced reporter, which is most strongly associated with carcinogenicity, was not activated by any of the tested nanoparticles.Conclusions We conclude that the ToxTracker reporter system can be used as a rapid mechanism-based tool for the identification of hazardous properties of metal oxide NPs. Furthermore, genotoxicity of metal oxide NPs seems to occur mainly via oxidative stress rather than direct DNA binding with subsequent replication stress.
    Particle and Fibre Toxicology 09/2014; 11(1):41. · 9.18 Impact Factor

Full-text (2 Sources)

Download
40 Downloads
Available from
Jun 4, 2014