Rheologic behavior of deoxyhemoglobin S gels

Area of Science:

• Biophysics
• Materials Science
• Hematology

Background:

• Sickle cell disease involves deoxyhemoglobin S polymerization.
• Understanding the physical properties of deoxyhemoglobin S gels is crucial for disease pathophysiology.

Purpose of the Study:

• To characterize the physical properties of deoxyhemoglobin S gels under physiologically relevant conditions.
• To investigate the factors influencing gel solidity, including annealing time and temperature.

Main Methods:

• Rotational rheometry was used to measure stress relaxation of deoxyhemoglobin S gels.
• Gels were subjected to constant shear strain after annealing.
• Ultracentrifugation was employed to determine pellet and polymer masses.

Main Results:

• Gel solidity, measured by yield temperature or stress, correlated with initial hemoglobin concentration, polymer mass, shear history, and annealing parameters.
• Annealing at 37°C significantly increased gel solidity over time, unlike annealing at 25°C.
• Increased solidity over annealing time was attributed to factors like alignment and water loss, not solely polymer mass.
• The presence of albumin did not alter gel behavior when polymer masses were comparable.

Conclusions:

• Gel annealing conditions must be standardized for reproducible rheological comparisons.
• Physical properties of deoxyhemoglobin S gels, influenced by polymer mass, shear history, and annealing, are vital for understanding sickle cell disorders.