Rheological properties of hemoglobin vesicles (artificial oxygen carriers) suspended in a series of plasma-substitute solutions

Hiromi Sakai, Atsushi Sato, Shinji Takeoka, Eishun Tsuchida*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


Hemoglobin vesicles (HbV) or liposome-encapsulated Hbs are artificial oxygen carriers that have been developed for use as transfusion alternatives. The extremely high concentration of the HbV suspension (solutes, ca. 16 g/dL; volume fraction, ca. 40 vol%) gives it an oxygen-carrying capacity that is comparable to that of blood. The HbV suspension does not possess a colloid osmotic pressure. Therefore, HbV must be suspended in or co-injected with an aqueous solution of a plasma substitute (water-soluble polymer), which might interact with HbV. This article describes our study of the rheological properties of HbV suspended in a series of plasma substitute solutions of various molecular weights: recombinant human serum albumin (rHSA), dextran (DEX), modified fluid gelatin (MFG), and hydroxylethyl starch (HES). The HbV suspended in rHSA was nearly Newtonian. Other polymers - HES, DEX, and MFG - induced HbV flocculation, possibly by depletion interaction, and rendered the suspensions as non-Newtonian with a shear-thinning profile (10 -4-103 s-1). These HbV suspensions showed a high storage modulus (G′) because of the presence of flocculated HbV. However, HbV suspended in rHSA exhibited a very low G′. The viscosities of HbV suspended in DEX, MFG, and high-molecular-weight HES solutions responded quickly to rapid step changes in shear rates of 0.1-100 s-1 and a return to 0.1 s-1, indicating that flocculation is both rapid and reversible. Microscopically, the flow pattern of the flocculated HbV that perfused through microchannels (4.5 μm deep, 7 μm wide, 20 cmH 2O applied pressure) showed no plugging. Furthermore, the time required for passage was simply proportional to the viscosity. Collectively, the HbV suspension viscosity was influenced by the presence of plasma substitutes. The HbV suspension provides a unique opportunity to manipulate rheological properties for various clinical applications in addition to its use as a transfusion alternative.

Original languageEnglish
Pages (from-to)8121-8128
Number of pages8
Issue number15
Publication statusPublished - 2007 Jul 17

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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