Surface and blood interaction properties of poly(ethylene oxide)-modified chitosan microspheres

Poly(ethylene oxide) (PEO)-containing triblock copolymer (Pluronics)-modifi ed chitosan microspheres were developed as potential blood-compatible hemoa dsorbants. Electron spectroscopy for chemical analysis (ESCA) was used to d etermine the surface elemental composition and the identity of the chemical functional groups on the surface. Fibrinogen adsorption, platelet adhesion and spreading were used as markers of blood compatibility. The high-resolu tion Cls spectrum of ESCA showed a significant increase in the relative int ensity of the -C-O- peak associated with ether carbon on the ethylene glyco l moiety of PEG, on Pluronic-modified chitosan microspheres. The ESCA resul ts confirm that the PEO chains of Pluronics were present on the surface of the the modified microspheres. Fibrinogen adsorption decreased by 50 and 85 % on chitosan microspheres modified with Pluronic F-68 and F-108 respective ly. The number of adherent platelets and the extent of platelet spreading w ere also reduced significantly on the Pluronic-modified chitosan surfaces. In addition, Pluronic F-108-modified microspheres adsorbed significantly mo re bilirubin than the unmodified microspheres. The results of this study sh ow that Pluronic-modified chitosan microspheres are blood-compatible hemoad sorbent matrices when used for the removal of toxic compounds.