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

工程无机纳米粒子（EINP）在环境中会发生变化，从而改变其移动性和毒性，例如，腐殖物质增加了纳米粒子的稳定性，而Ag纳米粒子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），这可以推断出的存在下，特定的Sers信号的NOM. Current测量技术提供有限的访问形成的涂层（如EXAFS无机涂层），但几乎没有时间分辨率。然而，由于分析的局限性，NP涂层的生命周期的监测尚未得到解决。在第一阶段中，拉曼显微光谱（RM）被应用于获得关于Ag NP上的涂层的信息。相关涂层可以通过RM或表面增强拉曼散射（Sers）来区分（即不同的腐殖物质、土壤提取物）。NOM附着到银纳米颗粒的光谱特征的变化表明涂层的老化，即NOM的结构的变化。通过子项目MASK和PORESURFACE获得的结果表明，与天然有机物的涂层可能被描述为紧密结合的第一层，产生Sers信号，和弱结合的第二层，其中荧光是NOM增强。第二阶段的工作计划是基于以下假设：初始涂层的形成和随后涂层的变化是在不同的时间线上，这取决于吸附系数;较高浓度的纳米颗粒可能会改变当地的化学环境;在空间限制条件（生物膜、孔喉、肠）下，可能产生浓度梯度。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规模，因此难以识别，但对于评估NP施加的压力非常重要。基于第一阶段的工作，时间分辨测量Ag NP和Au NP上涂层的稳定性和老化（Sers效应），然后是模型系统和真实的基质的时间分辨3D RM，这提供了EINP在自然系统中的化学环境和可能的变化的数据。选定的涂层实验将与SOILMOBILE和MASK联合进行。实验将包括Sers结构矩阵的测量，从而提供访问涂层和TiO 2 NP的化学环境。联合实验将解决EINP在空气-水界面的命运，EINP纳入生物膜的详细调查，涂层的老化，和时间分辨测量的EINP在水蚤。总之，这将提供一个机械的理解涂层的EINP在不同的媒体，导致评估的命运EINP。

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.