Engineered albumin-functionalized nanoparticles for improved FcRn binding enhance oral delivery of insulin

Oral delivery of biopharmaceuticals, as insulin, is hampered by rapid degradation and inefficient absorption in the gastrointestinal tract (GIT). To solve this, a new class of biodegradable poly(lactic-co-glycolic)-poly(ethylene glycol) (PLGA-PEG) mucodiffusive nanoparticles (NPs) was designed. Specifically, these were decorated with site-specific conjugated human albumin, engineered for improved pH dependent binding to the neonatal Fc receptor (FcRn), which naturally mediates transport of albumin across the intestinal epithelium. The designed NPs of monodisperse 150 nm in size were 10% loaded with insulin and their surface was successfully functionalized with human albumin. Importantly, the engineered albumin-functionalized NPs bound human FcRn favorably in a pH dependent manner and showed enhanced transport across polarized cell layers. When orally administered to human FcRn expressing mice induced with diabetes, a reduction of glycemia was measured as a function of receptor targeting, with up to around 40% reduction after 1 h post-delivery. Thus, biodegradable PLGA-PEG NPs decorated with human albumin for improved FcRn-dependent transport offer a novel attractive strategy for delivery of encapsulated biopharmaceuticals across intestinal barriers.