Abstract: | Core‐shell protein cluster comprising a hemoglobin (Hb) in the center and human serum albumins (HSA) at the exterior, Hb‐HSA 3 cluster, is an artificial O2‐carrier designed for use as a red blood cell (RBC) substitute. Lyophilization of the Hb‐HSA 3 cluster solution ([Hb unit] = 5 g/dL) with sucrose and trehalose yielded stable pink powder, which can be stored for 2 years at 4°C. Addition of pure water to the powder regenerated the homogeneous solution. The O2‐binding properties and oxyHb rate have been unaltered during the storage period. Infrared spectroscopic studies revealed that the hydrogen bond between protein and sugar stabilizes three‐dimensional structure of the cluster. |