*Article* **The Effect of Submicron Polystyrene on the Electrokinetic Potential of Cell Membranes of Red Blood Cells and Platelets**

**Marcin Zaj ˛ac <sup>1</sup> , Joanna Koty ´nska 2 , Mateusz Worobiczuk 2 , Joanna Breczko <sup>2</sup> and Monika Naumowicz 2, \***


**Abstract:** In recent years, many scientists have studied the effects of polymer micro- and nanostructures on living organisms. As it turns out, plastic can be a component of the blood of livestock, eaten by humans around the globe. Thus, it seems important to investigate possible changes in the physicochemical parameters and morphology of the cell membranes of blood morphotic elements (red blood cells and platelets) under the influence of polymer particles. The article presents research in which cell membranes were exposed to plain polystyrene (PS) and amino-functionalized polystyrene (PS-NH<sup>2</sup> ) of two different sizes. The polymers were characterized by infrared spectroscopy and dynamic light-scattering methods. To analyze possible changes caused by polymer exposure in the structure of the membranes, their zeta potentials were measured using the electrophoretic light-scattering technique. The concentration of the polymers, as well as the exposure time, were also taken into the consideration during the research. Based on the obtained results, we concluded that 100 and 200 nm PS, as well as 100 nm PS-NH<sup>2</sup> , internalize into the cells. On the contrary, 200 nm PS-NH<sup>2</sup> particles attach to cell membranes. Our study clearly shows that particle size and surface chemistry determine the interaction with biological membranes.

**Keywords:** polymers; erythrocytes; platelets; electrophoretic light scattering; dynamic light scattering; FTIR spectroscopy
