Study of the mechanism of insulin encapsulation in poly(isobutylcyanoacrylate) nanocapsules obtained by interfacial polymerization

Abstract

Abstract:In previous studies, insulin-loaded poly(alkylcyanoacrylate) nanocapsules were found to reduce the blood glucose level after oral administration to diabetic rats and dogs. The reduction of the glycemia induced by the nanocapsules was the same regardless of the insulin doses administered, but the effect appeared only after a delay of a few days. The purpose of this study was to investigate the mechanism of insulin encapsulation and the type of interactions that may exist between the polymer forming the nanocapsule wall and the insulin. The results of this study showed, based on the interfacial polymerization of isobutylcyanoacrylate, that the insulin molecule is not chemically modified during the nanoencapsulation process. In addition, no interaction between the poly(isobutylcyanoacrylate) and the insulin could be observed. The observed high encapsulation efficiency of intact insulin may be explained by the fact that the ethanol used in the preparation of the nanocapsules is responsible for the initiation of the interfacial polymerization of isobutylcyanoacrylate instead of the insulin. The zeta potential measurements suggest that insulin is located within the core of the nanocapsules. Thus the biological activity of the nanoencapsulated peptide and the high efficiency of insulin encapsulation achieved with this nanoencapsulation process cannot be explained by a specific interaction of the insulin with the polymer forming the nanocapsule's wall. It may be due, however, to the fact that the encapsulated insulin molecule is chemically intact and located within the oily core of the nanocapsules.

Polymeric Nanocapsules for Drug Delivery

“…Zeta potential measurements may also be used to investigate whether a biologically active compound is encapsulated within the nanocapsule oily core or adsorbed onto the particle surface (Aboubakar et al, 1999) and to confi rm nanocapsule coating by a specifi c material (Preetz et al, 2008). Zeta potential values may be generally associated with the pH values of the bulk (Sussman et al, 2007).…”

“…Although the encapsulation effi ciency of lipophilic drugs is generally related to drug solubility in the oily core (Fresta et al, 1996), hydrophilic compounds such as peptides have also been successfully encapsulated in oily-core nanocapsules prepared by chemical methods. One explanation for this may be the extremely rapid polymerization of the polymer occurring at the surface of the oil droplet, which limits the diffusion of the peptide toward the aqueous phase and therefore leads to higher entrapment in the nanocapsules (Aboubakar et al, 1999).…”

Methods of nanoparticle preparation

“…Recently, Aboubakar et al have entrapped insulin in poly(isobutylcyanoacrylate) nanoparticles, which were prepared by interfacial polymerization with high entrapment effi ciency. 31 Thus, these examples show that the interfacial polymerization technique allows the formation of nanoparticles with relatively high concentration of drug entrapment.…”

Nanoparticles: A Promising Drug Delivery Approach

“…It is a type of step-growth polymerization in which polymerization occurs at an interface between an aqueous solution containing one monomer and an organic solution containing a second monomer [38,39].…”