The Role of Pectin in Optimizing Cationic Liposomes for Oral Delivery

Liposomes are valuable in drug and vaccine delivery. However, due to limited stability in the gastric environment, there is a need to optimize liposomes for oral delivery. This study demonstrates the potential of pectin-coated cationic liposomes for mucosal delivery. Low methoxylated (LM), low methoxylated amidated (LMA), or high methoxylated (HM) pectins were coated onto cationic adjuvant formulation (CAF04) liposomes. The resulting liposomes were characterized to determine their in vitro stability in a simulated intestinal medium, interactions with mucins, and diffusivity across artificial mucus. Subsequently, liposome retention after in situ intestinal perfusion in rats and liposome uptake after incubation with macrophage-like cells were determined. In vitro stability tests in simulated intestinal fluid revealed that the pectin coating protected the liposomes against premature degradation. Mucin interaction studies showed that LM and LMA-pectin coatings created a protective buffer, avoiding excessive complexation with mucin. Diffusivity of the liposomes across artificial mucus revealed that the diffusivity of particles across mucus was influenced by both steric obstructions and interactive barriers. In situ intestinal perfusion demonstrated that pectin-coated liposomes were retained in the intestine, and cellular uptake studies confirmed that the pectin coating did not inhibit the uptake of the liposomes by macrophages. Overall, pectins demonstrated potential as excipients for mucosal delivery systems. In the context of oral liposome-based vaccine formulations, they can mitigate undesirable interactions such as complexation with bile salts and mucins, while preserving the cellular uptake efficiency of the particles.