Effect of Size on Magnetic Polyelectrolyte Microcapsules Behavior: Biodistribution, Circulation Time, Interactions with Blood Cells and Immune System

Drug carriers based on polyelectrolyte microcapsules remotely controlled with an external magnetic field are a promising drug delivery system. However, the influence of capsule parameters on microcapsules' behavior in vivo is still ambiguous and requires additional study. Here, we discuss how the processes occurring in the blood flow influence the circulation time of magnetic polyelectrolyte microcapsules in mouse blood after injection into the blood circulatory system and their interaction with different blood components, such as WBCs and RBCs. The investigation of microcapsules ranging in diameter 1-5.5 mu m allowed us to reveal the dynamics of their filtration by vital organs, cytotoxicity, and hemotoxicity, which is dependent on their size, alongside the efficiency of their interaction with the magnetic field. Our results show that small capsules have a long circulation time and do not affect blood cells. In contrast, the injection of large 5.5 mu m microcapsules leads to fast filtration from the blood flow, induces the inhibition of macrophage cell line proliferation after 48 h, and causes an increase in hemolysis, depending on the carrier concentration. The obtained results reveal the possible directions of fine-tuning microcapsule parameters, maximizing capsule payload without the side effects for the blood flow or the blood cells.

Automated summary

Drug carriers based on polyelectrolyte microcapsules controlled by an external magnetic field show promise as a drug delivery system. However, the impact of capsule parameters on their behavior in vivo remains unclear. This study demonstrates how microcapsules of different sizes interact with vital organs, blood cells, and magnetic fields, affecting circulation time, cytotoxicity, and hemotoxicity. Small capsules circulate longer without affecting blood cells, while larger capsules are quickly filtered, inhibit macrophage proliferation, and cause hemolysis depending on concentration. These findings suggest potential strategies to optimize microcapsule parameters for efficient drug delivery without adverse effects on blood flow or cells.