PEGylation of microspheres for therapeutic embolization: Preparation, characterization and biological performance evaluation

In this study, microspheres designed for embolization, defined as GF2000-Trisacryl (R) MS (GF-MS) and DEAF-Trisacryl (R) MS (DEAE-MS), were originally PEGylated using (3-amino propyl) triethoxy silane as coupling agent. Indomethacin was loaded into both PEGylated and non-PFGylated DEAE-MS, displaying ion-exchange ability, through a batch process with a respective capacity of 1.2 and 0.25 g/g. The morphology of naked and PEGylated MS was evaluated by scanning electron microscopy (SEM). Both micosphere resins surface looked like orange skin, although DEAE-MS showed a slightly rougher surface due to the copolymerization process. PEGylated microspheres have a most likely swelling surface owing to the presence of PEG hydrophilic chains. The mean diameters were of about 66 and 60 pm for GF-MS and DEAE-MS, respectively. Data obtained for PFGylated MS by Fourier Transform Infrared spectroscopy (FTIR) confirmed that microspheres were successfully PFGylated. Finally, complement activation in vitro was performed to evaluate the activating capacity of different microspheres. Both PEGylated GF-MS and DEAE-MS activated the complement system of about 33% less than their corresponding naked microspheres, while loading PEGylated DEAE-MS with indomethacin almost suppressed complement activation. This inhibiting role implies that PEGylation as well as loading the microspheres with antiinflammatory drug has a compact effect on the interaction of microspheres with blood proteins. (c) 2006 Elsevier Ltd. All rights reserved.