Yang Qiu

National Center for Nanoscience and Technology, Peping, Beijing, China

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Publications (7)46.52 Total impact

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    ABSTRACT: Commercially available carbon nanotubes (CNT) often contain some quantities of metallic and carbonaceous impurities. These impurities influence their physicochemical properties and performance, and accordingly a number of potential applications. The lack of information of metal impurities may also preclude accurate environmental and health risk assessments for specific CNT materials. To address these needs, a quantitative analysis of the metal contents has been made in a number of commercial carbon nanotubes produced by different manufacturers. More than 20 metals or metalloids were determined by neutron activation analysis. The results indicate arranging from 0.44 to 3 wt% of catalyst residues remained although the producers claim to provide a catalyst-free product. Most of the impurity elements are transition metals, such as Fe, Ni, Mo, Y, Co and Cr. In addition to the expected catalyst residues, other unexpected impurity elements were detected including As, Gd, W, Yb, Sm and so on. Metallic impurities in carbon nanotube materials should come from the large-scale production procedures, post fabrication and post-purification treatments. The analytical results determined by inductively-coupled plasma mass spectrometry show that a further deep purification using conventional acid reflux cannot completely remove the metallic impurities from carbon nanotubes. Post-production clean up is difficult and often incompletely.
    Journal of Nanoscience and Nanotechnology 03/2011; 11(3):2389-97. · 1.15 Impact Factor
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    ABSTRACT: We have observed that Au nanorods (NRs) have distinct effects on cell viability via killing cancer cells while posing negligible impact on normal cells and mesenchymal stem cells. Obvious differences in cellular uptake, intracellular trafficking, and susceptibility of lysosome to Au NRs by different types of cells resulted in selective accumulation of Au NRs in the mitochondria of cancer cells. Their long-term retention decreased mitochondrial membrane potential and increased reactive oxygen species level that enhances the likelihood of cell death. These findings thus provide guidance for the design of organelle-targeted nanomaterials in tumor therapy.
    Nano Letters 02/2011; 11(2):772-80. · 13.03 Impact Factor
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    ABSTRACT: Gold nanorods (Au NRs) have been recognized as promising materials for biomedical applications, like sensing, imaging, gene and drug delivery and therapy, but their toxicological issues are still controversial, especially for the Au NRs synthesized with seed-mediated method. In this study, we investigated the influence of aspect ratio and surface coating on their toxicity and cellular uptake. The cellular uptake is highly dependent on the aspect ratio and surface coating. However, the surface chemistry has the dominant roles since PDDAC-coated Au NRs exhibit a much greater ability to be internalized by the cells. The present data demonstrated shape-independent but coating-dependent cytotoxicity. Both the CTAB molecules left in the suspended solution and on the surface of Au NRs were identified as the actual cause of cytotoxicity. CTAB can enter cells with or without Au NRs, damage mitochondria, and then induce apoptosis. The effects of surface coating upon toxicity and cellular uptake were also examined using Au NRs with different coatings. When Au NRs were added into the medium, the proteins were quickly adsorbed onto the Au NRs that made the surface negatively charged. The surface charge may not directly affect the cellular uptake. We further demonstrated that the amount of serum proteins, especially for BSA, adsorbed on the Au NRs had a positive correlation with the capacity of Au NRs to enter cells. In addition, we have successfully revealed that the cationic PDDAC-coated Au NRs with an aspect ratio of 4 possess an ideal combination of both negligible toxicity and high cellular uptake efficiency, showing a great promise as photothermal therapeutic agents.
    Biomaterials 10/2010; 31(30):7606-19. · 7.60 Impact Factor
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    ABSTRACT: Publications concerning the mechanism of biological activity, especially the immunological mechanism of C(60)(OH)(20) nanoparticles, are relatively limited. However, the structure and characteristics of this carbon allotrope have been widely investigated. In this paper, we have demonstrated that water-soluble C(60)(OH)(20) nanoparticles have an efficient anti-tumor activity in vivo, and show specific immunomodulatory effects to the immune cells, such as T cells and macrophages, both in vivo and in vitro. For example, C(60)(OH)(20) nanoparticles can increase the production of T-helper cell type 1 (Th1) cytokines (IL-2, IFN- gamma and TNF-alpha), and decrease the production of Th2 cytokines (IL-4, IL-5 and IL-6) in serum samples. On the other hand, C(60)(OH)(20) nanoparticles show almost no adverse effect to the viability of immune cells in vitro but stimulate the immune cells to release more cytokines, in particular TNF- alpha, which plays a key role in the cellular immune process to help eliminate abnormal cells. TNF- alpha production increased almost three-fold in treated T lymphocytes and macrophages. Accordingly, we conclude that C(60)(OH)(20) nanoparticles have an efficient anti-tumor activity and this effect is associated with an increased CD(4)(+)/CD(8)(+) lymphocyte ratio and the enhancement of TNF- alpha production. The data suggest that C(60)(OH)(20) nanoparticles can improve the immune response to help to scavenge and kill tumor cells.
    Nanotechnology 10/2009; 20(41):415102. · 3.84 Impact Factor
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    ABSTRACT: It is known that down-regulation of the immune response may be associated with the progenesis, development and prognosis of cancer or infectious diseases. Up-regulating the immune response in vivo is therefore a desirable strategy for clinical treatment. Here we report that poly-hydroxylated metallofullerenol (Gd@C(82)(OH)(22)) has biomedical functions useful in anticancer therapy arising from immunomodulatory effects observed both in vivo and in vitro. We found that metallofullerenol can inhibit the growth of tumors, and shows specific immunomodulatory effects on T cells and macrophages. These effects include polarizing the cytokine balance towards Th1 (T-helper cell type 1) cytokines, decreasing the production of Th2 cytokines (IL-4, IL-5 and IL-6), and increasing the production of Th1 cytokines (IL-2, IFN-gamma and TNF-alpha) in the serum samples. Immune-system regulation by this nanomaterial showed dose-dependent behavior: at a low concentration, Gd@C(82)(OH)(22) nanoparticles slightly affected the activity of immune cells in vitro, while at a high concentration, they markedly enhanced immune responses and stimulated immune cells to release more cytokines, helping eliminate abnormal cells. Gd@C(82)(OH)(22) nanoparticles stimulated T cells and macrophages to release significantly greater quantities of TNF-alpha, which plays a key role in cellular immune processes. Gd@C(82)(OH)(22) nanoparticles are more effective in inhibiting tumor growth in mice than some clinical anticancer drugs but have negligible side effects. The underlying mechanism for high anticancer activity may be attributed to the fact that this water-soluble nanomaterial effectively triggers the host immune system to scavenge tumor cells.
    Biomaterials 05/2009; 30(23-24):3934-45. · 7.60 Impact Factor
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    ABSTRACT: Metal impurities in carbon nanotubes (CNTs) are undesirable for their uses in diverse applications, for instance, they may potentially have a negative health impact when using in biomedical fields. However, so far there is a lack of analysis methods able to quantify metallic impurities in CNTs. In this paper, using the neutron activation analysis (NAA) technique as a nondestructive standard quantification method and inductively coupled plasma mass spectrometry (ICPMS) as a practical approach, we established an analytical method for quantitative determination of metallic impurities in CNTs. ICPMS, one of the most sensitive analytical techniques used for coincident multielement measurements, has become a common tool in many laboratory, and thus it is easily available and a good selection for determining the metal impurities in CNTs. However, because of their extremely stable structure and the encapsulated metals in the defect structure, CNTs must undergo special pretreatments before ICPMS. We investigated different sample pretreatment procedures for ICPMS analysis, including dry ashing coupled with acid extraction, wet digestion, and a combination of dry ashing with acid digestion. With the reference data from the nondestructive analytical method of NAA, we found that the quantitative determination of metal impurities in CNTs is highly dependent on the sample pretreatment in which the conditions are largely different from those used for conventional biological samples or environmental materials. This paper not only provides the practical method and analysis conditions for quantifying the metal impurities of CNTs but also the first protocol for pretreatment processes of CNT samples.
    Analytical Chemistry 12/2008; 80(24):9426-34. · 5.70 Impact Factor
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    ABSTRACT: We demonstrated that three different types of water-soluble fullerenes materials can intercept all of the major physiologically relevant ROS. C(60)(C(COOH)(2))(2), C(60)(OH)(22), and Gd@C(82)(OH)(22) can protect cells against H(2)O(2)-induced oxidative damage, stabilize the mitochondrial membrane potential and reduce intracellular ROS production with the following relative potencies: Gd@C(82)(OH)(22)> or =C(60)(OH)(22)>C(60)(C(COOH)(2))(2). Consistent with their cytoprotective abilities, these derivatives can scavenge the stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH), and the reactive oxygen species (ROS) superoxide radical anion (O(2)(*-)), singlet oxygen, and hydroxyl radical (HO(*)), and can also efficiently inhibit lipid peroxidation in vitro. The observed differences in free radical-scavenging capabilities support the hypothesis that both chemical properties, such as surface chemistry induced differences in electron affinity, and physical properties, such as degree of aggregation, influence the biological and biomedical activities of functionalized fullerenes. This represents the first report that different types of fullerene derivatives can scavenge all physiologically relevant ROS. The role of oxidative stress and damage in the etiology and progression of many diseases suggests that these fullerene derivatives may be valuable in vivo cytoprotective and therapeutic agents.
    Biomaterials 12/2008; 30(4):611-21. · 7.60 Impact Factor

Publication Stats

306 Citations
46.52 Total Impact Points

Institutions

  • 2008–2011
    • National Center for Nanoscience and Technology
      Peping, Beijing, China
    • U.S. Food and Drug Administration
      • Center for Food Safety and Applied Nutrition
      Washington, D. C., DC, United States
  • 2009
    • Northeast Institute of Geography and Agroecology
      • Key Laboratory of Nuclear Analytical Techniques
      Beijing, Beijing Shi, China