The crucial role of a protein corona in determining the aggregation kinetics and colloidal stability of polystyrene nanoplastics

Nanosized plastics are considered as being a class of contaminants of emerging concern. The interaction between nanoplastics and proteins may significantly influence the environmental behavior and fate of nanoplastics. Here, we employed time-resolved dynamic light scattering to explore the aggregation kinetics and stability of polystyrene nanoparticles (PSNPs) exposed to a model globular protein (bovine serum albumin, BSA) in the presence of a number of typical electrolytes (NaCl, CaCl2, and Na2SO4). With the increase of the BSA concentration, the amount of BSA adsorbed on the surface of negatively charged PS-Bare (non-modified) and PS-COOH (carboxyl-modified) increased, resulting in higher dispersibility in comparison to the treatment without BSA. This stabilization effect derived from the protein corona structure was revealed by combining characterization techniques and visualized by transmission electron microscopy. Upon addition of NaCl and CaCl2, the aggregation of positively charged PS-NH2 (amino-modified) was inhibited by the BSA addition possibly due to the screening of the attractive patch-charge force and the competition for adsorption of cations between PS-NH2 and the protein. When Na2SO4 was present in the suspension, BSA addition significantly increased PS-NH2 aggregation rate due to patch-charge attraction and the high performance of SO42- in attaching to particles and charge neutralization. These findings shed light on the interactions between PSNPs and proteins, which were shown to vary with the composition of the surface coatings of PSNPs. The newly gained knowledge will help us to forecast the transport and fate of PSNPs in natural aqueous systems. (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study shows that different proteins play different roles in the interactions between nanoplastics and proteins, affecting the stability and aggregation kinetics of nanoplastics. The addition of different electrolytes also has varying effects on nanoplastics.