Yan Zhang,Xuli Du,Yu Zhang,Guofei Li,Cuifang Cai,Jinghua Xu,Xing Tang
This work deals with the synthesis of insulin loaded nanoparticles (NPs) composed of thiolated Eudragit L100 (Eul-cys) and reduced glutathione (GSH) as potential nanocarriers for oral delivery of insulin. Perfectly spherical NPs with an average particle size of nearly 200–300 nm are prepared. The insulin release from Eul-cys/GSH and Eul-cys NPs in PBS (pH 7.4) shows that GSH can slightly decrease the release rate of insulin. Eul-cys in combination with GSH or sodium caprate (SC) is evaluated for its permeation enhancing effect of FITC-insulin using the Caco-2 monolayer and Caco-2/HT29-MTX co-cultured cells models. SC results in greater permeation enhancement compared to GSH. However, GSH proves to be less toxic. Paracellular transport of insulin represents the main mechanism by which the NPs facilitate insulin permeation through the intestinal epithelium, whereas a number of NPs are also taken up by the cells and release insulin within the cells.
In this work, we designed and developed a delivery system composed of enteric Eudragit L100-cysteine/reduced glutathione nanoparticles (Eul-cys/GSH NPs) for oral delivery of insulin. First, interactions between Eul-cys and mucin glycoproteins, which are believed to be the result of disulfide bonds, were confirmed using rheology experiments. Subsequently, the insulin-loaded Eul-cys/GSH NPs were prepared by the diffusion method using the rich gel network multipore structure at the surface of the Eul-cys when the pH was higher than the p K a of Eul-cys polymer. The Eul-cys/GSH NPs obtained were characterized by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The results obtained showed that the average particle size ranged from 240 to 280 nm, and the particles were almost spherical in shape. The in vitro drug release results showed that the Eul-cys/GSH NPs retained a large amount of insulin in simulated gastric fluid, while a significant insulin release was found in simulated intestinal fluid. The in situ release study suggested that NPs released a greater amount of FITC-insulin (49.2 %) into the intestinal mucus layer compared with that of FITC-insulin solution (16.4 %), which facilitating insulin delivery through the intestinal mucosa. Eul-cys/GSH NPs exhibited promising mucoadhesive properties demonstrated using an in vitro cell model. Consequently, NPs were introduced into the ileum loop of healthy rats, thus enhancing the intestinal absorption of insulin and providing a prolonged reduction in blood glucose levels. These results suggest that Eul-cys/GSH NPs may be a promising delivery system for the treatment of diabetes.
In this work, the influence of type of supporting materials on the performance of form stable phase change materials (FSPCMs) was investigated. Two kinds of FSPCMs containing myristic acid (MA) were prepared using an inorganic material (bentonite) and a polymer (Eudragit L100) individually as the supporting material. The morphology, composition, crystalline properties, phase transition properties and heat storage/release performances of MA/bentonite FSPCMs (abbreviated as FSPCM-B) and MA/Eudragit L100 FSPCMs (abbreviated as FSPCM-E) were researched comparatively. The results show that the maximum MA content of FSPCM-B and FSPCM-E without melt MA leakage is 50 wt% and 70 wt%, respectively. All the prepared FSPCMs have good thermal reliability and reusability , and phase transition enthalpies of FSPCM-B are obviously lower than those of FSPCM-E with the same MA mass fraction. Due to the high thermal conductivity of bentonite, the heat transfer rate of FSPCM-B is exactly higher than that of FSPCM-E. This study will provide insights into the design and application of FSPCMs with inorganic matrix and polymeric matrix .
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