Biomembrane interactions in the toxicology of nanoparticles to microorganisms

纳米粒子和纳米材料在现代生活中的应用越来越多。然而，人们对其对生态系统和相关生物体的影响以及对人类健康可能产生的直接和间接有害影响表示关切。这一点非常重要，因为纳米粒子的物理和化学都相当反常。纳米颗粒的大小意味着它们在水体系中的行为介于溶解和颗粒之间。这也将适用于它们与生物有机体的相互作用和可能积累的情况。该提案是一项试验性研究，试图解决这些问题。我们建议使用两个简单但成熟的基本模型来更深入地了解纳米颗粒和纳米材料的生物活性和生物积累，这些纳米颗粒和纳米材料通常被认为是安全的。本研究的目的是评估纳米粒子的生物反应机制，细胞膜在这一过程中的参与，以及该机制与培养基质中纳米粒子的物理化学特性的关系。由汞电极上的磷脂单分子膜组成的经典膜电化学模型将被用来评估纳米颗粒的假定生物膜活性。细菌生物测定方法将与蓝藻培养物一起使用，以评估纳米颗粒的生物活性和生物积累。这两个模型上的两个系列实验将密切协调。大部分研究将用于：(I)表征纳米颗粒的大小、形状、表面电荷、晶体结构和组成，特别是在加入培养基时的分散性能；(Ii)研究纳米颗粒对模型生物膜系统的影响；(Iii)研究纳米颗粒对蓝藻培养物活力的影响。在这些初始实验中，电化学实验和生物测定实验都将在缓冲培养介质中进行。目的是验证生物膜在纳米颗粒的毒性机制中起关键作用的假设。在研究结束时，我们将基于这一假设开发出一种将纳米颗粒对蓝藻的生物活性与其物理和化学功能联系起来的方案。

Nanoparticles and nanomaterials are having in increasing application in modern life. There are concerns however about their effect on the ecosystem and associated organisms and possible harmful effects directly and indirectly on human health. This is very important because the physics and chemistry of nanoparticles is rather anomalous. The size of nanoparticles means that their behaviour in aqueous systems lies somewhere in between dissolved and particulate species. This will also apply to their interaction with and possible accumulation by biological organisms. This proposal is a pilot study which attempts to address these issues. We propose to use two simple but well established, fundamental models to obtain a deeper understanding of the biological activity and bioaccumulation of nanoparticles and nanomaterials which are generally considered as safe. The objective of the study is to evaluate the mechanism of the biological response to the nanoparticles, the involvement of the cell membrane in the process and the relationship of the mechanism to the physical chemical characteristics of the nanoparticles in the culture meda. The classical membrane electrochemical model consisting of a phopholipid monolayer on a mercury electrode will be employed to evaluate the putative biomembrane activity of the nanoparticles. A bacterial bioassay method will be used with cultures of cyanobacteria to assess the biological activity and the bioaccumulation of the nanoparticles. Both series of experiments on the two models will be closely coordinated. The bulk of the study will be spent:(i) Characterising the nanoparticles with respect to their particle size, shape, surface charge, crystal structure and composition both initially and when added to culture medium with particular attention to their properties in dispersion, (ii)Studying the effects of the nanoparticles on a model biological membrane system, (iii) Studying the effects of the nanoparticles on the viability of cyanobacterial cultures. In these initial experiments both the electrochemical and bioassay experiments will be carried out in a buffered culture medium. The aim is to test the hypothesis that the biological membrane is critical in the mechanisms of toxicity of the nanoparticles At the end of the study we shall have developed a protocol based on this hypothesis for relating the biological activity of nanoparticles towards cyanobacteria to their physical and chemical functionality.