Designing Engineered Materials for a Right Timing of Delivery from Layer-by-Layer Assembly

Sustained and Sequential Release (Long-term Delivery): Bio-inspired Approach -- Although Layer-by-Layer (LbL) assembly technique has been successfully used in various areas of nanotechnology and biotechnology, some LbL-assembled nanostructures have been suffered from lack of stability when they are exposed to any changes in aqueous environments (e.g. pH and ionic strength). In addition, this technique has been limited because of the diffusion of polyelectrolytes throughout the film during the deposition, resulting in poorly organized architectures, thus limiting the control of release characteristics. My current research is precisely aimed at addressing these problems. To this end, we have developed bio-inspired assembly strategies relying on biomimic moieties (chemical modification) and/or barrier layers (physical separation).

Stimulus Release (Quick Delivery): Mucoadhesive Drug Delivery System -- The mucus, owing to its easy accessibility, is an ideal organ system for adjuvant and antigen delivery to induce protective immunity. However the mobile and moist structure of mucosal tissues has brought substantial technical difficulties such as leakage, messiness, and low residence time to achieve a successful vaccination through mucus interface. To overcome these obstacles, we have been developing a pH-responsive mucoadhesive drug delivery system on membrane which consists of pH sensitive layer (sacrificial layer) and drug layer (effective layer) covered by bioadhesive layer on top. Immediate disintegration of pH sensitive layer at the interface between the system and membrane has been designed to quickly leave the system at a right position but in contact with mucosal layer. Concurrently, several types of bond formation across the interface between bioadhesive layer and mucus are expected to give rise to enhanced adhesion and therefore long-lasting attachment after application.