Construction of biconcave hemoglobin-based microcapsules and electrochemical evaluation for its ability of oxygen carry

Hemoglobin (Hb)-based oxygen carriers (HBOCs) have been investigated intensively. Enhancing the loading content of Hb in a red-blood-cell (RBC) like structure and seeking effective method to evaluate their oxygen-carrying capability have been the significant challenges. Here, we present unique biconcave Hb-Ca(OH)2 microcapsules of around 6.5 μm with high oxygen affinity using a facile and controllable method. Dextran introduced in the co-precipitation process can not only adjust the morphology of Ca(OH)2 particles but also improve the biocompatibility of the obtained microcapsules. The Hb entrapment efficiency in the microcapsules corresponded to 68% of the Hb content in one native RBC. The dynamic process of carrying-releasing oxygen of Hb-Ca(OH)2 microcapsules was investigated using electrochemical techniques. Hb in microcapsules on the surface of electrode maintained its naturally biological activity and exhibited a high ability to carry oxygen reversibly. The oxygen releasing of oxyHb-Ca(OH)2 microcapsules can be retained during at least 2400 s. The results demonstrate that Hb-Ca(OH)2 microcapsules with highly loaded content possessed excellent function of oxygen-binding and releasing, which make it promising for applications in artificial oxygen carriers and other biomedical fields.