Cell Cycle Control of Nanoplastics Internalization in Phytoplankton

Nanoparticles (NPs) for delivering chemotherapeutic drugs are now in clinical trials, and cellular uptake of NPs plays an important role in determining the drug delivery efficiency. Herein, we reported that the bioaccumulation and internalization of NPs were governed by the cell cycle. Specifically, we found that the bioaccumulation of NPs was more favored in the G(2)/M stages, followed by the S and G(0)/G(1) stages. We demonstrated that three key parameters-clathrin-mediated endocytosis capacity, algal cell membrane permeability, and exopolymer substance (EPS) thickness-were critical in the bioaccumulation of NPs during the cell cycling process. Over the 24-h average duration of cell cycle, clathrin-mediated endocytosis capacity was much higher at the S stage than that at the G(0)/G(1) and G(2)/M stages. Besides, cell membrane permeability was measured to be higher in S and G(2)/M stages while the lowest in G(0)/G(1) stage. We have also identified the change of EPS thickness during the 24-h cell cycle. Transition from G(0)/G(1) to S and G(2)/M induced the attenuation in EPS thickness, and the thinnest EPS was found at the end of mitosis. The cell cycle control NPs internalization were further verified by exposing Ag nanoparticles to algae at different cell cycle stages, confirming the important roles of EPS thickness and cell cycle control in the dynamic internalization processes. The present study highlights the important roles of cell cycle controlling the NPs bioaccumulation and internalization, with possible implications in maximizing NPs internalization efficiency while reducing the cost.

Automated summary

The study reveals that the cell cycle plays a crucial role in the bioaccumulation and internalization of nanoparticles, with different cell cycle stages showing varying characteristics in NP accumulation. Factors such as clathrin-mediated endocytosis capacity, algal cell membrane permeability, and exopolymer substance (EPS) thickness are identified as key determinants in NP bioaccumulation during the cell cycle.