Stimuli-responsive polymer-complexed liposome nanocarrier provides controlled release of biomolecules

Smart nanocarriers have recently attracted attention for their effective delivery of biomolecules to the intestine without degradation in the oral delivery field. In this study, we prepared a stimulus-responsive polymer complex containing liposomal nanocarriers, termed capsosomes, and examined their multi-level release properties in the oral delivery of hydrophilic molecules. The capsosomes were constructed as a trilaurin-based solid lipid nanoparticle (SLN) assembly coated with chitosan (CSLNs), with liposomal subcompartments. We investigated the pH sensitivity and behavior of capsosomes in vitro under simulated gastrointestinal (GI) conditions. Positively charged CSLNs with negatively charged liposomal subcompartments were complexed by electrostatic forces, and their thermodynamic characteristics were examined using isothermal titration calorimetry. The optimized formulation was a 1.6 M ratio of liposomes to CSLNs, yielding physically stable capsosomes. The complexed liposomes were released from capsosomes at pH 7.0. We compared the structural integrity and retention times of free liposomes and capsosomes using an in vitro digestion model. The capsosomes showed improved stability and prolonged retention time under small intestinal conditions and bypassed the GI tract. Approximately 87% of the complexed liposomes were released and transferred to the small intestinal membrane. These results demonstrate the potential application of pH-sensitive capsosomes for the oral delivery of food nutraceuticals.