Changes of nanoparticles along their life-cycle and of the local environment of nanoparticles

纳米颗粒沿生命周期的变化以及纳米颗粒局部环境的变化

• 批准号: 200690496
• 负责人: Professor Dr. Thomas Baumann
• 金额: --
• 依托单位: Lehrstuhl für Analytische Chemie und Wasserchemie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/200690496?language=en
• 关键词: Changes; nanoparticles; along; their; life

Engineered inorganic nanoparticles (EINP) in the environment undergo changes which alter their mobility and toxicity, for instance, humic substances increase the stability of NPs while sulfidic coatings on Ag NP limit the release of Ag+. After release into the environment NOM seems to form a rather stable coating around Ag NP. This coating possibly replaces the original stabilizing agent (e.g. citrate), which can be deduced by the presence of the specific SERS signal of NOM. Current measurement technology offers limited access to the formation of coatings (e.g. EXAFS for inorganic coatings) but virtually no time resolution. The monitoring of the life cycle of NP-coatings, however, has not yet been addressed, due to analytical limitations.In the first phase Raman microspectroscopy (RM) was applied to gain information about coatings on Ag NP. Relevant coatings can be distinguished (i.e. different humic substances, soil extract) by RM or surface enhanced Raman scattering (SERS). Changes in the spectral features of NOM attached to Ag NPs suggest an aging of coatings, that is a change of the structure of NOM. Results obtained by subprojects MASK and PORESURFACE indicate that a coating with natural organic matter might be described by a closely bound first layer, which produces a SERS signal, and a weakly bound secondary layer where the fluorescence is of NOM is enhanced. At least the secondary coating seems to be reversible.The work program in the second phase is driven by the following assumptions: the formation of an initial coating and subsequent changes of the coating are on different time lines, depending on the sorption coefficients; higher concentrations of NPs are likely changing the local chemical environment; under spatially restricted conditions (biofilm, pore throats, gut) concentration gradients might develop. Finally, unless very high concentrations of EINP are present, reactions at EINP are likely limited to a local scale, thus hard to identify but nevertheless important to assess the stress imposed by NP. Based on the work in the first phase time resolved measurements of the stability and aging of coatings on Ag NP and Au NP (SERS effect) will be followed by time resolved 3D RM of model systems and real matrices, which provide data on the chemical environment of EINP in natural systems and possible changes within. Selected coating experiments will be conducted jointly with SOILMOBILE and MASK. Experiments will include measurement on SERS structured matrices, thus offering access to the coating and the chemical environment of TiO2 NP. Joint experiments will address the fate of EINP at the air-waterinterface, the detailed investigation of EINP incorporated in biofilms, the aging of coatings, and time-resolved measurements of EINP in Daphnia. Together this will provide a mechanistic understanding of the coatings of EINP in different media leading to an assessment of the fate of EINP.

工程无机纳米颗粒（EINP）在环境中会发生改变，从而改变其流动性和毒性，例如，腐殖质物质增加了NPs的稳定性，而Ag NP上的硫化物涂层限制了Ag+的释放。释放到环境中后，NOM似乎在Ag NP周围形成了一层相当稳定的涂层。这种涂层可能取代原来的稳定剂（如柠檬酸盐），这可以通过NOM的特定SERS信号推断出来。目前的测量技术对涂层的形成（例如无机涂层的EXAFS）提供了有限的访问，但实际上没有时间分辨率。然而，由于分析的限制，对np涂层生命周期的监测尚未得到解决。在第一阶段，利用拉曼显微光谱（RM）获得银NP涂层的信息。通过RM或表面增强拉曼散射（SERS）可以区分相关涂层（即不同的腐殖质物质，土壤提取物）。附着在Ag NPs上的NOM光谱特征的变化表明涂层的老化，即NOM结构的变化。子项目MASK和PORESURFACE的结果表明，天然有机物涂层可能由紧密结合的第一层来描述，产生SERS信号，而弱结合的第二层则增强了NOM的荧光。至少二次涂层似乎是可逆的。第二阶段的工作计划由以下假设驱动：根据吸附系数的不同，初始涂层的形成和随后涂层的变化在不同的时间线上；NPs的高浓度可能正在改变当地的化学环境；在空间受限条件下（生物膜、孔喉、肠道），浓度可能会出现梯度。最后，除非存在非常高浓度的EINP，否则EINP的反应可能仅限于局部范围，因此难以识别，但对评估NP施加的压力很重要。在第一阶段工作的基础上，将对Ag NP和Au NP涂层的稳定性和老化进行时间分辨测量（SERS效应），随后将对模型系统和实际矩阵进行时间分辨三维RM，为自然系统中EINP的化学环境及其可能的变化提供数据。选定的涂层实验将与SOILMOBILE和MASK共同进行。实验将包括对SERS结构矩阵的测量，从而提供对TiO2 NP的涂层和化学环境的访问。联合实验将解决EINP在空气-水界面的命运，EINP在生物膜中的详细调查，涂层的老化，以及水蚤中EINP的时间分辨测量。总之，这将提供对EINP涂层在不同介质中的机理理解，从而对EINP的命运进行评估。