Heteroaggregation and eco-corona formation are important, interrelated processes that transform engineered nanoparticles (ENPs) and strongly impact their fate, transport and toxicity in natural and engineered systems. Yet, there is a lack of mechanistic information linking these processes. This work experimentally validates the hypothesis that attachment efficiencies can be predicted on the basis of the fraction of particle surfaces coated by organic matter. Heteroaggregation between branched polyethyleneimine gold nanoparticles (bPEI-AuNPs) and glass beads (a surrogate for naturally occurring suspended particulates) was examined in the presence and absence of Suwannee River natural organic matter (SRNOM) using a recently developed functional assay. Attachment efficiencies for heteroaggregation were quantified in systems where the relative concentrations of ENPs, glass beads and SRNOM were varied so as to systematically control the extent of eco-corona formation on the particle surfaces. Corona formation on the glass microspheres was negligible, but SRNOM readily adsorbed to the bPEI-AuNPs, reducing heteroaggregation. Measured attachment efficiencies were well described by a model correlating attachment efficiencies with the fractional coverage of the bPEI-AuNP surfaces by SRNOM, providing a promising mechanistic link between eco-corona formation and subsequent aggregation behavior. Further, the dependence of attachment efficiencies on the extent of eco-corona formation reveals the necessity that laboratory-based assays control the relative concentrations of ENPs, suspended particulates, and organic matter such that the resultant eco-corona formation is representative of that expected in the relevant environmental system.

中文翻译：

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天然有机物表面覆盖率可预测纳米颗粒与胶体之间的杂聚

异质聚集和生态电晕的形成是重要的，相互关联的过程，这些过程会转换工程化的纳米颗粒（ENP），并强烈影响其在天然和工程化系统中的命运，运输和毒性。但是，缺乏将这些过程联系起来的机械信息。这项工作实验性地验证了可以基于有机物覆盖的颗粒表面分数预测附着效率的假设。使用最近开发的功能测定法，在存在和不存在Suwannee河天然有机物（SRNOM）的情况下，检查了支链聚乙烯亚胺金纳米颗粒（bPEI-AuNPs）和玻璃珠（天然悬浮颗粒的替代物）之间的异质聚集。在其中ENP，玻璃珠和SRNOM相对浓度发生变化的系统中，对异质聚集的附着效率进行了定量分析，从而系统地控制了颗粒表面生态电晕的形成程度。在玻璃微球上电晕的形成可以忽略不计，但是SRNOM容易吸附到bPEI-AuNPs上，从而减少了异质聚集。用SRNOM将附着效率与bPEI-AuNP表面的部分覆盖率相关联的模型很好地描述了测得的附着效率，为生态电晕的形成与随后的聚集行为之间提供了有希望的机制联系。此外，依附效率对生态电晕形成程度的依赖性表明，基于实验室的测定法必须控制ENP，悬浮颗粒物，