Abstract
Effective oral drugs and vaccines require high delivery efficiency across the gastrointestinal epithelia and protection of medically effective payloads (i.e., immunogens) against gastric damage. In this study, hollowed nanocarriers (NCs: silica nanospheres and gold nanocages) with poly-l-lysine (PLL) coating and mammalian orthoreovirus cell attachment protein σ1 functionalization (NC-PLL-σ1) were explored as functional oral drug delivery vehicles (ODDVs). The transport of these ODDVs to mucosal lymphoid tissues could be facilitated by microfold cells (M-cells) mediated transcytosis (via σ1-α2-3-linked sialic acids adherence) across gastrointestinal epithelia. PLL coating provided protection and slow-release of rhodamine 6 G (R6G), a model payload. The transport effectiveness of these ODDVs was tested on intestinal organoid monolayers in vitro. When compared with other experimental groups, the fully functionalized ODDV system (with PLL-σ1) demonstrated two significant advantages: a significantly higher transport efficiency (198% over blank control at 48 h); and protection of payloads which led to both better transport efficiency and extended-release of payloads (61% over uncoated carriers at 48 h). In addition, it was shown that the M cell presence in intestinal organoid monolayers (modulated by Rank L stimulation) was a determining factor on the transport efficiency of the ODDVs: more M-cells (induced by higher Rank L) in the organoid monolayers led to higher transport efficiency for ODDV-delivered model payload (R6G). The fully functionalized ODDVs showed great potential as effective oral delivery vehicles for drugs and vaccines.