Distinct lipid membrane interaction and uptake of differentially charged nanoplastics in bacteria

• Published in: Journal of nanobiotechnology Vol. 20; no. 1; p. 191
• Main Authors: Dai, Shang, Ye, Rui, Huang, Jianxiang, Wang, Binqiang, Xie, Zhenming, Ou, Xinwen, Yu, Ning, Huang, Cheng, Hua, Yuejin, Zhou, Ruhong, Tian, Bing
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 15-04-2022; BioMed Central; BMC
• Subjects: Bacteria; Bacterial cell walls; Biodegradation; Bioremediation; Cell membranes; Differentially charge; E coli; Ecosystem; Ecosystems; Electrostatic interactions; Electrostatic properties; Electrostatic shielding; Environmental aspects; Escherichia coli; Gram-positive bacteria; Humans; Internalization; Lipid membrane; Lipid membranes; Lipids; Membrane Lipids; Membranes; Microbiological research; Microflora; Microplastics; Molecular dynamics; Nanomaterials; Nanoparticles; Nanoparticles - chemistry; Nanoplastics; Physiological aspects; Plastic pollution; Plastics; Polystyrene; Polystyrene resins; Polystyrenes - chemistry; Reactive oxygen species; Scanning electron microscopy; Strong interactions (field theory); Translocation; Uptake; China; Bacteria; Differentially charge; Lipid membrane; Uptake; Nanoplastics
• ISSN: 1477-3155; 1477-3155
• DOI: 10.1186/s12951-022-01321-z

Nanoplastics have been recently found widely distributed in our natural environment where ubiquitously bacteria are major participants in various material cycles. Understanding how nanoplastics interact with bacterial cell membrane is critical to grasp their uptake processes as well as to analyze their associated risks in ecosystems and human microflora. However, little is known about the detailed interaction of differentially charged nanoplastics with bacteria. The present work experimentally and theoretically demonstrated that nanoplastics enter into bacteria depending on the surface charges and cell envelope structural features, and proved the shielding role of membrane lipids against nanoplastics.
Positively charged polystyrene nanoplastics (PS-NH
, 80 nm) can efficiently translocate across cell membranes, while negatively charged PS (PS-COOH) and neutral PS show almost no or much less efficacy in translocation. Molecular dynamics simulations revealed that the PS-NH
displayed more favourable electrostatic interactions with bacterial membranes and was subjected to internalisation through membrane penetration. The positively charged nanoplastics destroy cell envelope of Gram-positive B. subtilis by forming membrane pore, while enter into the Gram-negative E. coli with a relatively intact envelope. The accumulated positively charged nanoplastics conveyed more cell stress by inducing a higher level of reactive oxygen species (ROS). However, the subsequently released membrane lipid-coated nanoplastics were nearly nontoxic to cells, and like wise, stealthy bacteria wrapped up with artifical lipid layers became less sensitive to the positively charged nanoplastics, thereby illustrating that the membrane lipid can shield the strong interaction between the positively charged nanoplastics and cells.
Our findings elucidated the molecular mechanism of nanoplastics' interaction and accumulation within bacteria, and implied the shielding and internalization effect of membrane lipid on toxic nanoplastics could promote bacteria for potential plastic bioremediation.