Exposure to polystyrene nanoparticles leads to changes in the zeta potential of bacterial cells

Abstract

Polymer molecules, the main components of plastics, are an emerging pollutants in various environmental compartments (water, air, soil) that may induce several ecotoxicological effects on live organisms. Therefore, understanding how plastic particles interact with bacterial cell membranes is crucial in analysing their associated risks in ecosystems and human microbiota. However, relatively little is known about the interaction between nanoplastics and bacteria. The present work focuses on Staphylococcus aureus and Klebsiella pneumoniae, representing the Gram-positive and Gram-negative bacteria respectively, exposed to 100 nm diameter polystyrene nanoparticles (PS NPs). The nanoparticles attach to the cells’ membranes of both bacteria, changing their electrical charge, but without the effect of killing the cells. PS NPs caused a change in zeta potential values (both species of bacterial strains), dependent on particle concentration, pH, as well as on exposure time of bacteria to them. Through the application of AFM and FTIR techniques, the presence of PS NPs on bacterial surfaces was detected, suggesting the affinity of the particles to bacterial components, but without any changes in the morphology of the tested bacteria. The zeta potential can be more widely used in the study of interactions between nanostructures and cells.

Green synthesis of silver nanoparticles and its environmental sensor ability to some heavy metals

“…The synthesized AgNPs' stability was evaluated using zeta potential measurements, with a higher positive or negative value suggesting greater nanoparticle stability [ 93 ]. The distribution of size, both by intensity and mass, is depicted in Fig.…”

“…7 c, indicative of high stability. Prior studies suggest that a strong negative zeta potential enhances repulsion between nanoparticles, promoting their stable dispersion and contributing to their colloidal quality [ 93 ]. Furthermore, the stability of AgNPs influences their size, with reduced stability leading to particle aggregation and an increase in particle size [ 94 ].…”

The heterogeneous diffusion of polystyrene nanoparticles and the effect on the expression of quorum-sensing genes and EPS production as a function of particle charge and biofilm age

“…30 As eDNA and pel possess a polyanionic nature, in the case of polystyrene NPs that are coated with positive and negatively charged molecules, electrostatic interactions can play a primary role 39 but not the only role in governing interactions between NPs and the P. aeruginosa matrix. Zając et al 40 demonstrated in biofilms, that the interactions of polystyrene NPs with the cell membranes of Staphylococcus aureus and Klebsiella pneumoniae led to changes in the zeta-potential of the bacterial cells, without causing cell death, and outcomes were dependent on particle concentration, pH, and exposure time. Additionally, studies have showed that kinetics of the interactions between biofilm components and functionalized nanoparticles were influenced by hydrophobic forces, van der Waals forces, pH, and steric hindrance.…”

Pulmonary toxicity assessment of polypropylene, polystyrene, and polyethylene microplastic fragments in mice

“…We hypothesized that a combination of other additional properties such as surface charges might account for these responses. Owing to their elevated surface-to-volume ratio, the surface charges of microplastics have been reported to play a crucial role in influencing their functions and interactions within biological systems, potentially resulting in adverse effects [ 48 ]. Zeta potential measurements provide information about particle charges and dispersion stability, with absolute values above 30 mV indicating low aggregation that leads to good homogenization following exposure [ 49 , 50 ].…”