Effect of antioxidants on enzyme-catalysed biodegradation of carbon nanotubes.
Effect of antioxidants on enzyme-catalysed biodegradation of carbon nanotubes.
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DOI：
10.1039/c2tb00047d
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发表时间：
2013
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影响因子：
--
通讯作者：
Star A
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文献类型：
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作者：
Kotchey GP;Gaugler JA;Kapralov AA;Kagan VE;Star A
碳纳米管（CNT）的日益增长的应用不可避免地增加了暴露于这种潜在有毒纳米材料的风险。为了解决这个问题，已经进行了研究来研究CNT的生物降解。特别是髓过氧化物酶（MPO），一种由包括人类在内的动物炎症细胞表达的酶，催化氧化碳纳米材料的降解。虽然MPO产生的活性中间体有效地降解氧化的单壁碳纳米管（o-SWCNT），酶催化生物降解的确切机制仍然不明确。在这项工作中，我们试图解释酶促氧化的氧化还原电位方面采用竞争性底物MPO，如氯，这是由MPO氧化形成强氧化剂（次氯酸盐），和抗氧化剂，具有较低的氧化还原电位比碳纳米管。采用透射电子显微镜，拉曼光谱，可见-近红外吸收光谱，我们证明，除了抗氧化剂，L-抗坏血酸和L-谷胱甘肽，有或没有氯化物显着减轻MPO催化的o-SWCNTs的生物降解。这项研究的重点是对酶降解碳纳米管的机制和抗氧化剂对这些途径的影响的基本认识。
The growing applications of carbon nanotubes (CNTs) inevitably increase the risk of exposure to this potentially toxic nanomaterial. In an attempt to address this issue, research has been implemented to study the biodegradation of CNTs. In particular, myeloperoxidase (MPO), an enzyme expressed by inflammatory cells of animals including humans, catalyse the degradation of oxidized carbon nanomaterials. While reactive intermediates generated by MPO efficiently degrade oxidized single-walled carbon nanotubes (o-SWCNTs); the exact mechanism of enzyme-catalysed biodegradation remains ambiguous. In this work, we tried to explain enzymatic oxidation in terms of redox potentials by employing competitive substrates for MPO such as chloride, which is oxidized by MPO to form a strong oxidant (hypochlorite), and antioxidants that have lower redox potentials than CNTs. Employing transmission electron microscopy, Raman spectroscopy, and vis-NIR absorption spectroscopy, we demonstrate that the addition of antioxidants, L-ascorbic acid and L-glutathione, with or without chloride significantly mitigates MPO-catalysed biodegradation of o-SWCNTs. This study focuses on a fundamental understanding of the mechanisms of enzymatic biodegradation of CNTs and the impact of antioxidants on these pathways.