Hemoglobin-Loaded Triblock PCLA-PEG-PCLA Copolymer Vesicles: A Potential Oxygen Carrier

Hemoglobin-loaded vesicles (Hb-Vesicles) have been developed for several years as cellular-type hemoglobin-based oxygen carriers (HBOCs). We in the present study reported a new type of Hb-Vesicles that were easily fabricated by poly(epsilon-caprolactone-co-lactide)-poly(ethylene glycol)poly(epsilon-caprolactone-co-lactide) (PCLA-PEG-PCLA) amphiphilic triblock copolymers via an improved water-in-oil-in-water (W/O/W) double emulsion method. Hemoglobin (Hb) was transferred to carbonylhemoglobin (CO-Hb) for Hb stabilization during the W/O/W encapsulation. The encapsulation efficiency and size distribution of the obtained CO-Hb-Vesicles were determined. The highest CO-Hb-Vesicles encapsulation efficiency could reach 67.5% with 180 nm particle diameters after optimization of encapsulation conditions, showing promising potential as long-circulating oxygen carriers. Finally, the CO-Hb in the vesicles could be converted to oxygen-binding hemoglobin (O-2-Hb) at a very short time by irradiation of visible light in oxygen atmosphere. The resultant Hb-Vesicles exhibited similar oxygen affinity to the native red blood cells demonstrating that this nano-system can serve as a promising HBOC.