Biomimetic Viruslike and Charge Reversible Nanoparticles to Sequentially Overcome Mucus and Epithelial Barriers for Oral Insulin Delivery

Abstract

Nanoparticles (NPs) for oral delivery of peptide/protein drugs are largely limited due to the coexistence of intestinal mucus and epithelial barriers. Sequentially overcoming these two barriers is intractable for a single nanovehicle due to the requirements of different or even contradictory surface properties of NPs. To solve this dilemma, a mucus-penetrating virus-inspired biomimetic NP with charge reversal ability (P-R8-Pho NPs) was developed by densely coating poly(lactic- co-glycolic acid) NPs with cationic octa-arginine (R8) peptide and specific anionic phosphoserine (Pho). The small size (81.81 nm) and viruslike neutral charged surface (-2.39 mV) of the biomimetic NPs achieved rapid mucus penetration, which was almost equal to that of the conventional PEGylated mucus-penetrating nanoparticles. The hydrolysis of surface-anchored anionic Pho was achieved by intestinal alkaline phosphatase, which led to the turnover of ζ potential to positive (+7.37 mV). This timely charge reversal behavior also exposed cationic R8 peptide and induced efficient cell-penetrating peptide (CPP)-mediated cellular uptake and transepithelial transport on Caco-2/E12 cocultured cell model. What's more, P-R8-Pho NPs showed excellent stability in simulated gastrointestinal conditions and enhanced absorption in intestine in vivo. Finally, oral administration of insulin-loaded P-R8-Pho NPs enabled to induce a preferable hypoglycemic effect and a 1.9-fold higher oral bioavailability was achieved compared with single CPP-modified P-R8 NPs on diabetic rats. The combinative application of biomimetic mucus-penetrating strategy and enzyme-responsive charge reversal strategy in a single nanovehicle could sequentially overcome mucus and epithelial barriers, thus showing great potential for the oral peptide/protein delivery.

Recent progress in drug delivery

“…For overcoming the barriers of mucus, mucus-adhesive NPs (MAPs) and mucus-penetrating NPs (MPPs) have been developed, and results have revealed that MPPs diffused more freely than MAPs, exhibiting improved distribution and access to the absorptive epithelium203, 204. In addition, shape and elasticity are also reported to affect mucus diffusion205, 206.…”

Oral Delivery of Biologics for Precision Medicine

“…This is the case of the EGP peptide‐functionalized PLGA nanoparticles,50 targeting heparan sulfate proteoglycans (HSPGs). The same strategy was adopted51 to decorate PLGA NPs with octa‐arginine (R8) peptide linked to phosphoserine (PhO). In theory, the brush border intestinal alkaline phosphatase (IAP) would catalyze the hydrolysis of PhO from the nanoparticles surface, hence exposing the cationic R8 residues, which would promote cell uptake.…”

<p>Phospholipid complex based nanoemulsion system for oral insulin delivery: preparation, in vitro, and in vivo evaluations</p>

“…To confirm the maintained biological activity of insulin after encapsulated into IPC-NEs, the hypoglycemic effects of the released insulin were evaluated in normal rats according to a previous report 23. After subcutaneous injection, the released insulin from IPC-NEs and IPC showed similar hypoglycemic profiles as compared to the equivalent dose of free insulin (1 IU/kg; Figure 6A).…”

“…To imitate the GT environment, we conducted in vitro release study in SGF for the first 2 hrs and in SIF for another 6 hrs, without enzymes 23. As illustrated in Figure 4A, both of free insulin and IPC had a fast release profile, with more than 80% of the insulin were released within the first 2 hrs.…”