Preparation and Investigation of the Effect of Alginate Nanoparticles Coated by Trimethylchitosan (TMC) and Polyethylene Glycol (PEG) for Oral Delivery of Insulin

In diabetic patients, insulin secretion from the pancreas is altered which leads to daily insulin injection. Insulin injection causes infection, pain, and stress in the long term. Oral insulin delivery can be an appropriate alternative for injection. However, in oral delivery, due to enzymatic degradation in the gastrointestinal tract, low stability in gastric pH, and physical barriers of intestinal epithelium layer, insulin bioavailability is low. Thus, the synthesis of effective carriers such as nanoparticles can be a suitable solution for protecting sensitive drugs such as insulin. This study aims to develop a Nano-sized system of alginate/ trimethyl chitosan (TMC)/ polyethylene glycol (PEG) system in order to control the insulin release and increase the residence time of the nanoparticles in the gastrointestinal tract. At first, the size of the nanoparticles and Entrapment Efficiency (EE) of insulin were optimized and the optimal conditions for alginate/ insulin, alginate/ TMC ratios, and stirring rate were 1, 4.5, and 500 rpm, respectively. Then, at optimal conditions, insulin loaded alginate nanoparticles were prepared, followed by coating with TMC and finally, the nanoparticles were PEGylated with methoxy polyethylene glycol (mPEG). After optimization, the sizeof the nanoparticles and EE obtained as 195 nm and 92.39%, respectively, and Loading Efficiency (LE) of insulin was calculated as 21.75%. Interaction between the different layers also, was verified using FT-IR analysis andin vitro, insulin release investigation was carried out in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF). These studies showed that the highest insulin release takes place within the initial 6 h, and then the release trend will be constant. Also, insulin release significantly was increased by nanoparticle pegylation.