Curcumin-Lipid Interactions in PEGylated vs. Conventional Liposomes: A Combined Fluorescence and EPR Study

Area of Science:

• Biochemistry and Biophysics
• Materials Science and Nanotechnology

Background:

• Curcumin exhibits therapeutic potential but suffers from poor bioavailability due to low solubility and rapid degradation.
• Nanoformulation, particularly PEGylated liposomes, offers a promising strategy to enhance curcumin delivery and overcome its limitations.

Purpose of the Study:

• To investigate curcumin-membrane interactions within saturated (DMPC) and unsaturated (POPC) liposomes, with and without PEGylation.
• To assess the impact of PEGylation on curcumin loading efficiency and its orientation within liposomal bilayers.

Main Methods:

• Fluorescence spectroscopy was used to determine curcumin binding affinity (K_d) to liposomes.
• Fluorescence quenching and electron paramagnetic resonance (EPR) spectroscopy with spin labels were employed to study curcumin's orientation and its effects on membrane properties (fluidity, polarity, oxygen transport).

Main Results:

• PEGylated DMPC liposomes demonstrated the strongest binding affinity for curcumin.
• Curcumin adopts a transbilayer orientation in all examined membranes.
• PEGylation did not significantly alter membrane properties, while curcumin reinforced membranes, increased polarity, and reduced oxygen transport.

Conclusions:

• Liposomes, especially PEGylated DMPC liposomes, are effective delivery vehicles for curcumin.
• The study provides insights into curcumin-membrane interactions, supporting the use of PEGylated liposomes for enhanced curcumin bioavailability.