Submicron polymer membrane hemoglobin nanocapsules as potential blood substitutes: preparation and characterization

Biodegradable polymer membrane nanocapsules containing hemoglobin have been prepared with phase separation and polymer precipitation methods. We have used different polymers including polylactic acid and polyisobutyl-cyanoacrylate. The mean diameter of the hemoglobin nanocapsules can be as low as 0.07 mu and up to 0.39 mu dependent on the method of preparation. The concentration of the hemoglobin in the suspension can be up to 11 gm/dl, as compared to 15 gm/dl in whole blood. The viscosity of the preparation is slightly lower than that of human blood. In vitro tests show that P50 of these nanocapsules containing bovine hemoglobin is identical to free bovine hemoglobin solution. The surface of the nanocapsules can be modified for example with polyethylene glycol(PEG) or with PEG 2000 PE. Preliminary in vivo tests show that surface modified nanocapsules containing hemoglobin can survive longer in the circulation.