Surface Coating of Red Blood Cells with Monomethoxy poly(ethylene glycol) Activated with Two Different Reagents

Methoxy poly(ethylene glycol) (mPEG) with molecular mass of 5 kDa activated with succinimidyl carbonate and cyanuric chloride, separately was covalently attached to human red blood cells (RBCs). Inhibition of agglutination by blood-type specific antisera (anti-D) was employed to evaluate the effect of the polymer coating. The remaining single cells after incubation with anti-D sera were counted using a simple hemocytometer (Improved Neubauer Ruling). The extent of surface coating was evaluated by addition of FITC labeled-anti-D to the cells and recording the fluorescence intensity ratio of FITC-anti-D bound cells of the PEG-RBCs versus control (uncoated) RBCs. The morphology of RBCs was evaluated by scanning electron microscopy (SEM). The effect of polymer coating, based on the immunological response of RBCs, using two kinds of activated mPEG, at optimum conditions of PEGylation was compared. It was found that succinimidyl carbonate at its optimum condition (pH=8.7, temperature =14C and reaction time =60 min) is more effective than cyanuric chloride at its optimum condition (pH=8.7, temperature =14 C and reaction time =30 min) for RBC coating with mPEG.