Bead-type polystyrene/nano-CaCO₃ (PS/nCaCO₃) composite: a high-performance adsorbent for the removal of interleukin-6

A novel nano-CaCO₃ (nCaCO₃) particle composite-derived polystyrene (PS) resin was successfully synthesized by a suspension polymerization method. The nCaCO₃ reinforced PS material (PS/nCaCO₃) possessed a structure with abundant mesopores of high porosity, high specific surface area (828.3 m² g^-1) and large pore volume (1.83 cm³ g^-1). It was revealed that the incorporation of nCaCO₃ into the PS matrix enhanced both the mechanical strength which can prevent the fragmentation and its adsorption capacity for interleukin-6 (IL-6, M_W = 24.0 kDa) from human plasma. The adsorption isotherm could be described by the Langmuir model and classified as S-3 type, showing an IL-6 uptake of up to 25.6 ng g^-1 at an equilibrium concentration of about 500 ng L^-1. The adsorption capacity for IL-6 of PS/nCaCO₃ is not only significantly higher than that of PS (without nCaCO₃), but also superior to those of currently available adsorbents that are under clinical studies (e.g., CytoSorb™ towards cytokines). In addition, the PS/nCaCO₃ adsorbent also had good hemocompatibility and showed no leakage of nCaCO₃ in the plasma in a flowing model system. Therefore, the synthesized PS/nCaCO₃ nano-composite has a great potential to be used as an efficient adsorbent for the removal of interleukin-6 (IL-6) from blood of inflammatory and auto-immune disease patients through hemoperfusion.