Studies On Enteric-coated Insulin-chitosan Complex Nanoparticles

It has been the focus of the research works and problem urgently needed to be resolved that choosing suitable carriers for the oral administration of protein and peptide in order to enhance the absorption and bioavailability. In this paper, the enteric-coated insulin-chitosan complex nanoparticles (EICCN) were prepared through ionic cross-linking method using chitosan as materials. Firstly, the preparation conditions of the insulin-citosan complex were evaluated, and the obtained complex was simply identified. Then the preparation, physicochemical properties, drug release behavior in vitro and the factors, which influence the preparation, were investigated. At last, the hypoglycemic effect of EICCN and the influence of uptake of food, dosage, frequency of delivery and enzyme inhibitor were also evaluated.The HPLC method for the measurement of insulin was found, and the suitability of this system was evaluated. The results indicated that the concentration of insulin was liner relative to the area of the chromatogram peak between 10-100 μg/ml, and the accuracy, recovery, limit of determination and limit of quantitation were all satisfied.According to the principle of ionic cross-linking method, the insulin loaded uncomplex chitosan nanoparticles were prepared. The optimum formulation was obtained through orthogonal design with the particle size and entrapment efficiency as the requirement, ie, concentration of chitosan, insulin and TPP wasl.6mg/ml, 0.64mg/ml and 0.6mg/ml, respectively. The particle size, zeta potential and the entrapment of the nanoparticles was 204nm, 30.4mv and 36.3%, respectively. The influence of degree of deacetylate (DD) of chitosan was also investigated and the results indicated that the particle size was decreasing and the entrapment efficiency was increasing with the increasing of DD of chitosan.The complex of insulin and chitosan was prepared and the influence of factors and the characteristics of complex were evaluated. During the factors, the DD of chitosan, pH value of the insulin solution, the mass ratio of chitosan to insulin (Mr) and their concentration could somehow affect the preparation of complex. The complex was analyzed through DSC and IR method, and the results that the peak of insulin in complex was disappeared indicated the possibility of the formation of complex. In IR analysis, the peaks representing the acetylated amine group in complex (peaks at 3365.0cm^-1 for -NH, 1575.8cm^-1 for N-H and 1409.2cm^-1 for C-N) were significantly stronger than that in insulin, chitosan and their mixture. Also the decrease of peaks at 1654.6cm^-1 and 1575.8cm^-1 for C=O indicated the formation of many acetylated amine groups. The weaker peaks at 1081.8cm^-1 for C-O-H and 2959.5cm^- for O-H...