Rapid leakage from PEGylated liposomes triggered by bubbles

Area of Science:

• Colloidal science and materials science
• Biophysical chemistry and drug delivery systems

Background:

• Liposomes serve as effective colloidal carriers for drugs and proteins.
• Physicochemical stimuli-triggered leakage from liposomes has broad biochemical and biomedical applications.
• PEGylated liposomes are utilized to improve drug delivery characteristics.

Purpose of the Study:

• To investigate the effects of air bubbles on the characteristics of PEGylated liposomes.
• To examine the encapsulation and release of 5(6)-carboxyfluorescein from liposomes under varying conditions.

Main Methods:

• Fabrication of PEGylated liposomes using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and DSPE-PEG with PEG moieties of 550 or 5000 Da.
• Generation of air bubbles using a bubble column at specific gas velocities.
• Measurement of dye leakage from liposomes in static liquid, gas-liquid flow, and liquid shear flow.

Main Results:

• Leakage from PEGylated liposomes was significantly accelerated by air bubbles at 25 or 40 °C and pH 7.4.
• The dye release rate constant in gas-liquid flow was 168 times higher for liposomes with 1 mol% DSPE-PEG (5000 Da) compared to static conditions.
• Leakage was minimal in non-PEGylated liposomes and less pronounced in liquid shear flow without bubbles, indicating bubble-liposome interaction is key.

Conclusions:

• The interaction between air bubbles and PEGylated liposomes is responsible for the rapid leakage of encapsulated contents.
• Adsorption of PEGylated lipids to bubbles likely induces leaky lipid bilayers, affecting drug release.
• Findings highlight the potential of bubble-mediated processes for controlled release from liposomal drug delivery systems.