Chemo-Mechanical Interactions to Improve Intestinal Retention of Ingestible Medical Devices

 Addressing the challenge of retaining medical devices within the small intestine while minimizing tissue trauma is a significant clinical endeavor. Current methods like tissue-piercing microneedles cause inflammation due to epithelial damage, while mucoadhesives are prone to fouling. To tackle this issue, inspiration is drawn from the structure of intestinal villi, and a novel approach is explored: using high-aspect-ratio elastomeric microposts to mechanically interlock with the villi, creating intestinal retentive platforms.

To assess the feasibility of mechanical interlocking, comprehensive mechanical simulations are conducted. The effectiveness of micropost interlocking based on variables such as their elastic moduli and the degree of overlap with villi are characterized. This study extends to intricate models that analyze the interplay between devices equipped with microposts and the villi. By adjusting micropost density, arrangement, and tip geometry, their resilience against peristaltic stresses is evaluated. Subsequently, simulations are validated by fabricating microposts and artificial soft villi using Digital Light Processing 3D printing along with a multi-step replica-molding technique. The interlocking behavior between the fabricated villi and interlockers is quantified using lap-shear tests on a custom in vitro test bed. 

The validation process not only reinforces the simulations but also lays the groundwork for employing computational techniques in the analysis of elastomeric mechanical interlocking systems in future endeavors. These innovative devices introduce a compliant and non-invasive approach to developing intestinal retentive platforms. 

Beyond the realm of mechanical interlocking, the application of genipin — a naturally derived protein crosslinker, to create gelatin-based hydrogels is explored. Their application as robust intestinal mucoadhesives is studied and they are further used to create radially self-expanding mucoadhesive stents for intestinal retention.