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首页> 外文期刊>Environmental Science & Technology >Extracellular Saccharide-Mediated Reduction of Au~(3+) to Gold Nanoparticles: New Insights for Heavy Metals Biomineralization on Microbial Surfaces
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Extracellular Saccharide-Mediated Reduction of Au~(3+) to Gold Nanoparticles: New Insights for Heavy Metals Biomineralization on Microbial Surfaces

机译：细胞外糖介导的Au〜（3+）还原为金纳米粒子：微生物表面重金属生物矿化的新见解。

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摘要

Biomineralization is a critical process controlling the biogeochemical cycling, fate, and potential environmental impacts of heavy metals. Despite the indispensability of extracellular polymeric substances (EPS) to microbial life and their ubiquity in soil and aquatic environments, the role played by EPS in the transformation and biomineralization of heavy metals is not well understood. Here, we used gold ion (Au~(3+)) as a model heavy metal ion to quantitatively assess the role of EPS in biomineralization and discern the responsible functional groups. Integrated spectroscopic analyses showed that Au~(3+)was readily reduced to zerovalent gold nanoparticles (AuNPs, 2-15 nm in size) in aqueous suspension of Escherichia coli or dissolved EPS extracted from microbes. The majority of AuNPs (95.2%) was formed outside Escherichia coli cells, and the removal of EPS attached to cells pronouncedly suppressed Au~(3+) reduction, reflecting the predominance of the extracellular matrix in Au~(3+) reduction. XPS, UV-vis, and FTIR analyses corroborated that Au~(3+) reduction was mediated by the hemiacetal groups (aldehyde equivalents) of reducing saccharides of EPS. Consistently, the kinetics of AuNP formation obeyed pseudo-second-order reaction kinetics with respect to the concentrations of Au~(3+) and the hemiacetal groups in EPS, with minimal dependency on the source of microbial EPS. Our findings indicate a previously overlooked, universally significant contribution of EPS to the reduction, mineralization, and potential detoxification of metal species with high oxidation state.
机译：生物矿化是控制生物地球化学循环，命运以及重金属潜在环境影响的关键过程。尽管胞外聚合物（EPS）对微生物的生存和在土壤和水生环境中的普遍存在是不可或缺的，但EPS在重金属转化和生物矿化中所扮演的角色尚未得到很好的理解。在这里，我们使用金离子（Au〜（3+））作为模型重金属离子，定量评估EPS在生物矿化中的作用并识别负责的官能团。集成光谱分析表明，Au〜（3+）在大肠杆菌的水悬浮液或从微生物中提取的溶解的EPS中很容易还原为零价金纳米颗粒（AuNPs，大小为2-15 nm）。大多数AuNPs（95.2％）是在大肠杆菌细胞外形成的，去除附着在细胞上的EPS明显抑制了Au〜（3+）的还原，反映出胞外基质在Au〜（3+）还原中的优势。 XPS，UV-vis和FTIR分析证实了Au〜（3+）的还原是由EPS还原糖的半缩醛基（醛当量）介导的。一致地，相对于EPS中Au〜（3+）和半缩醛基团的浓度，AuNP形成的动力学服从伪二级反应动力学，而对微生物EPS来源的依赖性最小。我们的发现表明，EPS对具有高氧化态的金属物种的还原，矿化和潜在的解毒作用具有普遍被忽视的贡献。

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  • 来源
    《Environmental Science & Technology》 |2017年第5期|2776-2785|共10页
  • 作者

    Fuxing Kang; Xiaolei Qu; Pedro J. J. Alvarez; Dongqiang Zhu;

  • 作者单位

    College of Resources and Environmental Sciences, Nanjing Agricultural University, Jiangsu 210095, China ,State Key Laboratory of Pollution Control and Resource Reuse/School of the Environment, Nanjing University, Jiangsu 210046,China;

    State Key Laboratory of Pollution Control and Resource Reuse/School of the Environment, Nanjing University, Jiangsu 210046,China;

    Department of Civil and Environmental Engineering, Rice University, Houston Texas 77005, United States;

    School of Urban and Environmental Sciences, Peking University, Beijing 100871, China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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