Glutamine-Chitosan Microparticles as Oral Insulin Delivery Matrix: In Vitro Characterization

Chitosan at physiological pH lacks positive charge which reduces the mucoadhesivity and permeation enhancing capacity. Therefore glutamine conjugated chitosan (GC) was developed to enhance the protonation of chitosan at intestinal pH. Particles were prepared by sodium tripolyphosphate ionic crosslinking and were evaluated in vitro for its application toward oral insulin delivery. The particles had high positive charge of 35.6 +/- 7.3 mV at physiological pH and a size of 4.434 mu m. The mucoadhesive capacity was established in vitro using rat intestinal tissue. Transepithelial electrical resistance (TEER) and confocal microscopy studies proved the ability of the particles in opening the tight junctions in Caco 2 monolayers. The permeation of fluorescent dextran (M-W 4000; FD4) across intestinal tissue was evaluated using Franz diffusion apparatus. It was observed that the GC particles enhanced the permeation by 1.52 fold in comparison with native chitosan (NC) particles. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 2374-2382, 2011