Construction and Evaluation of Hemoglobin-Based Capsules as Blood Substitutes

Hemoglobin‐based capsules for use as blood substitutes are successfully fabricated by covalent layer‐by‐layer assembly. Dialdehyde heparin (DHP) is used both as one of the wall components and a cross‐linker without employing other extraneous or toxic crosslinking agents. The biocompatibility of (Hb/DHP)6 microcapsules is evaluated through the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) (MTT) assay and cell experiments. The hemocompatibility of (Hb/DHP)6 microcapsules is characterized in terms of prothrombin time, thrombin time, activated partial thromboplastin time, and hemolysis rate. The oxygen‐carrying capacity of the microcapsules is demonstrated by converting the deoxy‐Hb state of the microcapsules into the oxy‐Hb state. All these results demonstrate that the hemoglobin‐based microcapsules exhibit oxygen‐carrying capacity as well as biocompatibility and hemocompatility, indicating that the as‐prepared capsules have great potential to function as blood substitutes. Biocompatible, biodegradable, and blood‐compatible hemoglobin‐based microcapsules used as blood substitutes are successfully fabricated by covalent layer‐by‐layer assembly. Given the advantages of the layer‐by‐layer assembly technique, the construction and behavior of these hemoglobin‐based capsules are controllable and adjustable, which makes the obtained capsules promising candidates for applications as blood substitutes, oxygen carriers, and in other biomedical fields.