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Adsorption of essential micronutrients by carbon nanotubes and the implications for nanotoxicity testing

Division of Engineering Brown University, Providence, RI 02912, USA.
Small (Impact Factor: 7.51). 06/2008; 4(6):721-7. DOI: 10.1002/smll.200700754
Source: PubMed

ABSTRACT A study used biochemical profiling techniques and ultraviolet (UV) visible spectroscopy, to demonstrate that single-walled nanotubes (SWNTs) caused dose-dependent adsorption and depletion of more than 14 amino acids and vitamins from RPMI cell culture medium. It was found that HepG2 cells cultured through these techniques, showed significantly reduced viability that can be restored by replenishment of folate. The study demonstrated a new mechanism through which hydrophobic nanotube formulations influenced cell behavior indirectly. The study involved the dispersion of SWNTs in RPMI cell culture medium at different doses and sonicating for 30 minutes, to conduct investigations.

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Available from: Annette von dem Bussche, Mar 28, 2014
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    • "In the same way, CNTs reduce mobility and micro-limiting effect on the bioavailability of nutrients present in the aqueous medium (Oleszczuk et al., 2011). Guo et al. proved that there is an unambiguous correlation between concentration of SWCNTs and concentration of critical small molecules in the culture medium (Guo et al., 2008). This relationship, based on hydrophobic and p–p interactions between backbones of aminoacids , folic acid and other vitamins, was found as responsible for the indirect cytotoxicity of SWCNTs since the nutrients were only weakly specifically adsorbed by nanotubes. "
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    ABSTRACT: Due to their unique molecular architecture translating into numerous every-day applications, carbon nanotubes (CNTs) will be ultimately an increasingly significant environmental contaminant. This work reviews qualitative/quantitative analyses of interactions of various types of CNTs and their chemically modified analogues with aqueous/aquatic media containing organic and inorganic contaminants and selected organisms of aquatic ecosystems. A special emphasis was placed on physicochemical interactions between CNTs as adsorbents of heavy metal cations and aromatic compounds (dyes) with its environmental consequences. The studies revealed CNTs as more powerful adsorbents of aromatic compounds (an order of magnitude higher adsorption capacity) than metal cations. Depending on the presence of natural organic matter (NOM) and/or co-contaminants, CNTs may act as Trojan horse while passing through biological membranes (in the absence of NOM coordinating metal ions). Nanotubes, depending on flow conditions and their morphology/surface chemistry, may travel with natural waters or sediment with immobilized PAHs or metals and/or increase cyto- and ecotoxicity of PAHs/metal ions by their release via competitive complexation, or cause synergic ecotoxicity while adsorbing nutrients. Additionally, toxicity of CNTs against exemplary aquatic microorganisms was reviewed. It was found for Daphnia magna that longer exposures to CNTs led to higher ecotoxicity with a prolonged CNTs excretion. SWCNTs were more toxic than MWCNTs, while hydrophilization of CNTs via oxidation or anchoring thereto polar/positively charged polymer chains enhanced stability of nanotubes dispersion in aqueous media. On the other hand, bioavailability of functionalized CNTs was improved leading to more complex both mechanisms of uptake and cytotoxic effects. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Chemosphere 05/2015; 136:211–221. DOI:10.1016/j.chemosphere.2015.04.095 · 3.50 Impact Factor
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    • "Therefore, a systematic study is required to investigate the interactions between amino acids and CNTs in aqueous solution . Additionally, Guo et al. experimentally showed that CNTs caused adsorption and depletion of essential micronutrients (including 14 amino acids and vitamins) in cell culture medium and significantly reduced HepG2 cell viability, which revealed a novel mechanism of the indirect nanotoxicity of CNTs [37]. This experimental study also calls for a simulation study to provide more molecular-level details. "
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    ABSTRACT: The adsorption of 20 standard amino acids on (6,6) carbon nanotube (CNT) at a concentration of 0.17 M and neutral pH has been studied by molecular dynamics simulations, to assess the suitability of amino acids for CNT aqueous dispersions. Simulation results show that among the 20 amino acids, phenylalanine, tyrosine, tryptophan and arginine exhibit the strongest affinity for CNT(6,6) in terms of adsorption amount and interaction energy. These amino acids adsorb to CNT(6,6) and form very stable aggregates, covering about half of the tube surface. Phenylalanine, tyrosine and tryptophan interact with the tube via the strong π–π stacking of their aromatic rings. Interestingly, the strong attraction of arginine to CNT(6,6) mainly attributes to its guanidinium group, which strongly interacts with the tube and forms multiple salt bridges. The negatively charged carboxylate and positively charged ammonium groups of these adsorbed amino acids extend away from the tube surface and point towards aqueous solution, which facilitates the solubilization of CNTs in water, and may be able to provide electrostatic repulsion forces to prevent CNT agglomeration. The results of this work provide a theoretical support for using amino acids as novel CNT dispersing agents and help to understand CNT–protein interactions.
    Carbon 09/2014; 78:500-509. DOI:10.1016/j.carbon.2014.07.031 · 6.16 Impact Factor
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    • "Whether in the GIT or a culture microenvironment, NP will develop a corona of adsorbed proteins, small molecules, and ions (Cedervall et al., 2007; Faunce et al., 2008; Lundqvist et al., 2008; Monopoli et al., 2011). This association can sequester nutrients, etc., complicating interpretation of cell culture results (Guo et al., 2008), and create an 'epitope map', or complex biologically active entity that influences the in vivo response (Lynch et al., 2007; Monopoli et al., 2011). The effects of the protein corona are variable. "
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    ABSTRACT: The increasing interest in nanoparticles for advanced technologies, consumer products, and biomedical applications has led to great excitement about potential benefits but also concern over the potential for adverse human health effects. The gastrointestinal tract represents a likely route of entry for many nanomaterials, both directly through intentional ingestion or indirectly via nanoparticle dissolution from food containers or by secondary ingestion of inhaled particles. Additionally, increased utilisation of nanoparticles may lead to increased environmental contamination and unintentional ingestion via water, food animals, or fish. The gastrointestinal tract is a site of complex, symbiotic interactions between host cells and the resident microbiome. Accordingly, evaluation of nanoparticles must take into consideration not only absorption and extraintestinal organ accumulation but also the potential for altered gut microbes and the effects of this perturbation on the host. The existing literature was evaluated for evidence of toxicity based on these considerations. Focus was placed on three categories of nanomaterials: nanometals and metal oxides, carbon-based nanoparticles, and polymer/dendrimers with emphasis on those particles of greatest relevance to gastrointestinal exposures.
    01/2013; 3(1-2). DOI:10.1504/IJBNN.2013.054515
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