Investigation of the Migration Patterns for Nanoplastics With Different Sizes in Chlorella vulgaris and Their Effects on Heavy Metal Adsorption by the Microalgae

Polystyrene nanoparticles (PS-NPs) size determines their adsorption by Chlorella vulgaris , which induces size-dependent changes in cell membrane properties, and these two effects synergistically regulate the alga's heavy metal adsorption capacity via the carrier effect of PS-NPs. By using laser scanning confocal microscopy (LSCM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA), it assessed resultant changes in cellular membrane parameters and explored the influence of different-sized PS-NPs, acting as carriers, on algal adsorption of heavy metals. C. vulgaris achieved adsorption for three nanoparticle size fractions within 1 h. Following uptake by C. vulgaris , PS-NPs of different sizes exhibited distinct intracellular and extracellular distribution patterns. Smaller NPs entered cells, while larger ones remained surface-bound. Following adsorption of polystyrene nanoparticles of varying sizes, C. vulgaris exhibited alterations in cell membrane parameters, including increased hydrophobicity and decreased permeability. These changes were size-dependent. Notably, PS-NPs of different sizes demonstrated distinct capacities for adsorbing Hg 2+ , Cd 2+ , and Pb 2+ . PS-NPs were found to influence the adsorption of these heavy metals by C. vulgaris through altering cell membrane parameters and acting as carriers for the metal ions, thereby modifying the alga's equilibrium adsorption capacity.