Eco-Corona Dictates Mobility of Nanoplastics in Saturated Porous Media: The Critical Role of Preferential Binding of Macromolecules

Abstract

Nanoplastics are an increasing environmental concern. In aquatic environments, nanoplastics will acquire an eco-corona by interacting with macromolecules (e.g., humic substances and extracellular polymeric substances (EPS)). Here, we show that the properties of the eco-corona and, consequently, its ability to enhance the transport of nanoplastics vary significantly with the surface functionality of nanoplastics and sources of macromolecules. The eco-corona derived from the EPS of Gram-negative Escherichia coli MG1655 enhances the transport of polystyrene (PS) nanospheres in saturated porous media to a much greater extent than the eco-corona derived from soil humic acid and fulvic acid. In comparison, the eco-corona from all three sources significantly enhance the transport of carboxylated PS (HOOC-PS). We show that the eco-corona inhibits the deposition of the two types of nanoplastics to the porous media mainly via steric repulsion. Accordingly, an eco-corona consisting of a higher mass of larger-sized macromolecules is generally more effective in enhancing transport. Notably, HOOC-PS tends to acquire macromolecules of lower hydrophobicity than PS. The more disordered and flexible structures of such macromolecules may result in greater elastic repulsion between the nanoplastics and sand grains and, consequently, greater transport enhancement. The findings of this study highlight the critical role of eco-corona formation in regulating the mobility of nanoplastics, as well as the complexity of this process.

Efficient Extraction and Analysis of Nanoplastics by Ionic Liquid-Assisted Cloud-Point Extraction Coupled with Electromagnetic Heating Pyrolysis Mass Spectrometry

“…HA is a typical component in real environment, and can affect the detection and migration of nanoplastics. 34,35 The characteristic ions of PMMA and PS were not influenced by various HA concentrations (Figure S6). The extraction efficiencies of PMMA and PS with various HA concentrations are shown in Figure 3c.…”

Multifaceted Aquatic Environmental Differences between Nanoplastics and Microplastics: Behavior and Fate

“…After heteroaggregation of NPs with natural colloids, an encapsulation layer of NPs covered by natural colloids tends to form, which is an eco-colloid layer, also known as an eco-corona . Eco-corona usually shows colloidal stability, strong biosorption capacity and pollutant transport capacity, which leads to altered aggregation and dispersion of NPs and affects their stability in the aquatic environment. , Since electrolytes in the aquatic environment interact with natural colloids, the role of natural colloids on NPs is specifically analyzed according to the level of electrolyte content (i.e., ionic strength) in the aquatic environment . In the aquatic environment that do not contain large amounts of electrolytes, the presence of EPS and HA increases the stability of NPs in the aquatic environment by increasing the steric hindrance and electrostatic repulsion, making the NPs less likely to aggregate.…”

Binding of Tetrabromobisphenol A and S to Human Serum Albumin Is Weakened by Coexisting Nanoplastics and Environmental Kosmotropes

“…Results suggested that the pH and chemical heterogeneity of BFRs is essential in determining the ternary BFR-protein-PN interactions. The resultant protein orientation, corona thickness, and particle aggregation status may greatly influence PN transport, cellular uptake, cytotoxicity, 40 and environmental mobility, 41 which eventually govern their fate.…”