水体中胞外聚合物作用下单层二硫化钼的化学转化机制及生物效应研究

Single-layer molybdenum disulfide (SLMoS2) is one of the most high-profile graphene-like nanomaterials in environmental and catalysis field. However, the chemical transformation behaviors and health risks of SLMoS2 after entering the aquatic environment still remain unknown. The preliminary experiments have found that SLMoS2 in water environment could be chemically transformed to produce soluble Mo and S species. In this project, the chemical transformations and relevant micro-mechanisms of SLMoS2 nanosheet in aquatic environment under the action of the extracellular polymeric substance (EPS) are entirely revealed through analyzing the ionic release, surface chemistry, the variations of catalytic properties and the crystal structure (phase), while the role effects of environmental factors (oxygen, light and pH) are also taken into consideration. Further, zebrafish is targeted as an aquatic model organism, and fluorescence imaging, metabolomics, and proteomics are employed to elucidate the influence and molecular mechanisms of EPS on the growth and development toxicity of aquatic animal induced by SLMoS2. The project aims to radically expound the transformation process of SLMoS2 and relevant biological responses, which will provide theoretical basis for the safety design of SLMoS2 nanosheet in environmental field and play an important guiding role for the development of emerging industries based on graphene-like nanomaterials.

单层二硫化钼（SLMoS2）是现今环境和化学领域最受关注的类石墨烯纳米材料之一，然而其进入环境后的化学转变行为及生态健康危害尚不清楚。预实验发现SLMoS2在水体中可发生化学溶解，释放出可溶性离子。本课题以水体环境为中心，观察SLMoS2纳米材料离子释放、表面化学特性、晶体结构和催化性质的变化，揭示微生物胞外聚合物（EPS）作用下SLMoS2的化学转变过程，明确环境介质（溶解氧、光照和pH）对其转化过程的影响，并从电子传递和表面电荷密度方面阐释其微观机理；然后以斑马鱼为模式生物，借助荧光成像、代谢和蛋白质组学等技术手段，阐明EPS调控SLMoS2纳米材料水生动物生长发育毒性的分子机制。本课题旨从根本上明确环境生物介质作用下SLMoS2的化学转化行为及对其生物效应的影响，为其在环境领域的安全设计提供理论基础，对类石墨烯纳米材料产业的发展具有重要指导意义。

单层二硫化钼（MoS2）是最具研究意义和应用价值的类石墨烯纳米材料之一。鉴于其独特的理化特征和显著的纳米效应，MoS2释放进入环境后必然对生态安全造成威胁，研究其天然水体中的化学行为转变及毒性效应对其生态风险评估及合理应用至关重要。本项目研究了胞外聚合物、硫醇化合物等生物介质与的单层MoS2相互作用及对其理化特性和环境行为归趋的影响；揭示了单层MoS2与共存重金属污染物的复合转化过程及其影响因素，并从电荷转移的角度阐明其微观机理；以小球藻（Chlorella vulgaris）和斑马鱼（Danio rerio）为模式生物，阐释了单层MoS2诱发典型水生生物毒性作用的分子机制，并分析了生物分泌物对单层MoS2毒性效应的调控作用。主要结论如下：（i）环境生物分子中的巯基官能团是单层MoS2主要的结合位点，引入含碳亲水性官能团越多，单层MoS2化学稳定性和胶体稳定性增强越显著；（ii）单层MoS2可作为供体向吸附Ag+转移电子，将其还原为Ag纳米颗粒，光照条件下Ag+还原效率显著高于黑暗条件，阳离子（Na+和Ca2+）共存抑制Ag+还原，硫醇基团修饰则显著促进该转化过程；（iii）微藻细胞光合Fe−S中心是单层MoS2的作用靶点，硫空位和粒径显著影响单层MoS2纳米片的毒性作用，氧化应激和蛋白损伤减弱、以及纳米颗粒外排速率加快是生物分泌物定植降低单层MoS2毒性效应的主要原因。项目研究结果为科学评估MoS2纳米材料的生态环境风险及其合理设计应用提供理论依据和技术支撑。