Encapsulation of hemoglobin in phospholipid vesicles

Area of Science:

• Biomaterials Science
• Biochemistry
• Drug Delivery Systems

Background:

• Hemoglobin (Hb) is a potential oxygen carrier but is unstable when encapsulated.
• Traditional encapsulation methods use harsh chemicals detrimental to Hb integrity.
• Developing stable Hb-based oxygen carriers (HBOCs) is crucial for medical applications.

Purpose of the Study:

• To develop a solvent-free method for encapsulating hemoglobin in phospholipid vesicles.
• To assess the stability and oxygen-binding properties of encapsulated hemoglobin.
• To compare the efficacy of different lipid compositions for Hb encapsulation.

Main Methods:

• Hemoglobin/lipid mixtures were extruded through polycarbonate membranes to form vesicles.
• Photon correlation spectroscopy was used to determine vesicle size.
• Oxygen binding and methemoglobin formation were measured under various conditions.

Main Results:

• A homogeneous vesicle preparation with a mean size of 2400 Å was achieved.
• Encapsulated hemoglobin retained reversible oxygen binding and impermeability to ions.
• Vesicles made with dimyristoyl phosphatidylcholine, cholesterol, and dicetyl phosphate showed enhanced stability, remaining intact for at least 14 days at 4°C.

Conclusions:

• The extrusion technique provides a safe and effective method for creating stable hemoglobin-loaded vesicles.
• Specific lipid compositions significantly improve the shelf-life of encapsulated hemoglobin.
• These findings support the development of advanced hemoglobin-based oxygen carriers.