(141d) Engineering High Oxygen Affinity Oxygen Carriers

Eike, J., University of Notre Dame

Oxygen carriers based on glutaraldehyde polymerized hemoglobin (PolyHb) are currently being developed for use in human subjects needing blood transfusions. Though there has been a great deal of research on the glutaraldehyde (G) hemoglobin (Hb) reaction, a systematic study of the effect of varying the G-Hb molar ratio on the resulting PolyHb physical properties (molecular weight distribution and oxygen binding parameters) has not been conducted to date. The results of this study show that increasing the G-Hb molar ratio elicits a general decrease in the P50 and cooperativity, and a simultaneous increase in the weight averaged molecular weight of the PolyHb dispersion and methemoglobin (MetHb) level. Three PolyHb dispersions (20:1, 30:1, and 40:1 G-Hb molar ratios) exhibited potential as oxygen carriers. The 20:1 PolyHb dispersion resulted in the presence of more intramolecularly crosslinked and non-crosslinked tetramers versus crosslinked species that were larger than a tetramer (~75% tetrameric and ~25% higher order species), lower MetHb level (8%), and P50 (20.1 mmHg) similar in magnitude to that of non-crosslinked Hb. The 30:1 PolyHb dispersion consisted of more higher order species (~76%), higher MetHb level (28%), and lower P50 (13.3 mmHg). The 40:1 PolyHb dispersion resulted in a similar P50 of 13.0 mmHg, similar MetHb level (30%), however this PolyHb dispersion only consisted of species larger than a tetramer. Taken together, the results of this study should aid in engineering appropriate molecular weight distributions and oxygen binding properties of potential oxygen carriers.