Preparation and characterisation of poly(lactic acid) hemoglobin microspheres

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Development of effective blood substitutes is crucial for transfusion medicine.
• Hemoglobin-based oxygen carriers (HBOCs) are promising alternatives to red blood cells.
• Challenges include hemoglobin stability, toxicity, and oxygen-binding properties.

Purpose of the Study:

• To develop and characterize polylactid microspheres for hemoglobin encapsulation.
• To assess the structural integrity and oxygen-carrying function of encapsulated hemoglobin.
• To evaluate the potential of these microspheres as blood substitutes.

Main Methods:

• Emulsification of hemoglobin solution into polylactid in methylene chloride to form W/O emulsion.
• Addition to an external aqueous phase with stirring for methylene chloride evaporation.
• Microsphere separation by filtration, washing, and characterization (size, morphology).
• Spectroscopic analysis (absorption spectra) and oxygen dissociation curve determination.
• Cellulose acetate gel electrophoresis to confirm hemoglobin integrity.

Main Results:

• Spherical polylactid microspheres with sizes ranging from 10 to 500 microns were successfully prepared.
• Over 80% of hemoglobin was encapsulated within the microspheres.
• Encapsulated hemoglobin showed no spectral alterations, indicating structural preservation.
• Oxygen dissociation curves demonstrated functional oxygen permeability and a P50 similar to free hemoglobin.
• Electrophoresis confirmed the presence of intact hemoglobin, suggesting no chemical interaction with the polymer.

Conclusions:

• The developed microencapsulation process effectively preserves hemoglobin's structure and function.
• Polylactid microspheres show promise as a stable and functional hemoglobin-based oxygen carrier.
• This method offers a potential route for creating safe and effective blood substitutes.