Binding of Tetrabromobisphenol A and S to Human Serum Albumin Is Weakened by Coexisting Nanoplastics and Environmental Kosmotropes
Zongshan Zhao, Haimei Li, Jiaqiang Yao, Jing Lan, Yan Bao, Lining Zhao, Wansong Zong, Qing Zhang, Henner Hollert, Xingchen Zhao
Abstract
Human serum albumin (HSA) was used as a model protein to explore the effects of brominated flame retardant (BFR) binding and the corona formation on polystyrene nanoplastics (PNs). Under physiological conditions, HSA helped to disperse PNs but promoted the formation of aggregates in the presence of tetrabromobisphenol A (TBBPA, Δ D h = 135 nm) and S (TBBPS, Δ D h = 256 nm) at pH 7. At pH 4, these aggregates became larger with fewer electrostatic repulsion effects (Δ D h = 920 and 691 nm for TBBPA and TBBPS, respectively). However, such promotion effects as well as BFR binding are different due to structural differences of tetrabromobisphenol A and S. Environmental kosmotropes efficiently stabilized the structure of HSA and inhibited BFR binding, while the chaotropes favored bioconjugated aggregate formation. Such effects were also verified in natural seawater. The newly gained knowledge may help us anticipate the behavior and fate of plastic particles and small molecular pollutants in both physiological and natural aqueous systems.