Gastrointestinal distribution of engineered biodegradable urease-powered nanomotors.

Abstract

The oral route is the most patient-friendly option for drug administration, yet biological barriers often limit its effectiveness. Chief among these is the mucus layer along the gastrointestinal (GI) tract, which restricts the transport of drugs and carriers. Strategies such as mucolytics, mucus-inert materials, and anisotropic nanosystems have been employed to enhance penetration. We developed urease-powered poly(lactic-co-glycolic acid) (PLGA) nanomotors for drug delivery, featuring either random (isotropic) or spatially localized (anisotropic, Janus-like) urease surface functionalization. Anisotropic nanomotors were prepared by immobilizing PLGA nanoparticles (NPs) at the oil-water interface of Pickering emulsions, followed by urease conjugation via carbodiimide chemistry. Cryogenic scanning electron microscopy confirmed interfacial localization and immunoelectron microscopy unveiled urease spatial distribution. The resulting nanomotors catalyzed the conversion of urea to ammonia and carbon dioxide, enabling enhanced diffusion in urea-containing environments. Isotropic NPs showed a two-fold higher enzymatic conversion rate compared to anisotropic ones, attributed to higher enzyme availability, with negligible levels observed for passive PLGA NPs. All NPs were coated with poloxamer 407 (P407) for stabilization, yielding particles under 200 nm with low polydispersity and near-neutral charge. The P407 coating slightly reduced nanomotor mobility in fluids at the single-particle level, while it seems to have improved in vitro cell uptake in the presence of urea. In vivo studies in rats revealed that urease-functionalized nanomotors transited the GI tract and appeared to show enhanced localization at the epithelial surface, when compared to passive counterparts and regardless of urease distribution configuration. These findings highlight the potential of both isotropic and anisotropic urease-powered PLGA nanomotors to overcome GI barriers and serve as drug delivery platforms. STATEMENT OF SIGNIFICANCE: New designs for urease-powered polymeric nanoparticles (nanomotors) are proposed in this work to circumvent hurdles introduced by mucosae. Nanomotors featured either random or spatially oriented distribution of urease at their surface. The latter was achieved by means of Pickering emulsion and partial surface modification. Using these approaches, we demonstrated that both nanomotors convert urea into carbon dioxide and ammonia, resulting in enhanced diffusion in aqueous media. Nanomotors were safe in vitro, and capable of providing extensive distribution throughout the gastrointestinal tract following oral administration to rats, accumulating in the vicinity of the epithelium. The main findings suggest that such bioresorbable nanosystems have the potential to tackle important biological barriers and presumably be used as oral drug delivery vehicles.