Various types of microfabricated devices have been proposed for overcoming the gastrointestinal (GI) challenges associated with oral administration of pharmaceutical compounds. However, unidirectional drug release in very close forced proximity to the intestinal wall still appears to be an unresolved issue for many of these microdevices, which typically show low drug absorption and thereby low bioavailabilities. This work explores how recently developed and promising self-unfolding foils (SUFs) can be magnetically and/or radiopaquely (M/R-) functionalized, by the addition of BaSO4 or Fe3O4 nanoparticles, for improving their applicability within oral drug delivery. Through surface characterization, mechanical testing, and X-ray imaging, the (M/R-)SUFs are generally inspected and their overall properties compared. Furthermore, R-SUFs are being used in an in vivo rat X-ray imaging study, whereas in situ rat testing of MR-SUFs are attempted together with an investigation of their general magnetic properties. Unfolding of the R-SUF, and its very close forced proximity to the small intestine, is very easily observed 2 h post-administration by applying both computed tomography scanning and planar X-ray imaging. In addition, MR-SUFs show a great magnetic response in water, which suggests the possibility for controlled motion and retention in the GI tract. However, the magnetic response does not seem strong enough for in situ rat testing, but most likely a strong magnetization of the MR-SUFs using for example an impulse magnetizer can be made for increasing the magnetic response. All of the results presented herein are highly relevant and applicable for future usage of (M/R-)SUFs, as well as similar devices, in pre-clinical studies and potential clinical trials.
Keywords: gastrointestinal (GI) retention and proximity; in vivo and in situ rat studies; mechanical and magnetic properties; micro-computed tomography (μ-CT) scanning; polydimethylsiloxane (PDMS).