Surface-modified PLGA nanoparticles with chitosan for oral delivery of tolbutamide.

The main purpose of present study was to develop novel chitosan-modified polylactic-co-glycolicacid nanoparticles (CS@PLGA NPs) for improving the bio-availability of tolbutamide (TOL). The TOL-loaded CS@PLGA NPs (TOL-CS@PLGA NPs) were fabricated with the solvent evaporation method. The cargo-free CS@PLGA NPs showed a diameter of 228.3±2.5nm monitored with a laser light particlesizer, and the transmission electron microscope (TEM) photographs revealed their "core-shell" structures. The Zeta potential of the original PLGA NPs and the cargo-free CS@PLGA NPs was measured to be -20.2±3.21mV and 24.2±1.1mV, respectively. The changes in Zeta potential indicated the CS chains were coated on the surfaces of the original PLGA NPs. The thermal gravity analysis (TGA) curves suggested that the CS chains improved the thermostability of the original PLGA NPs. The results of cells viability indicated the cargo-free CS@PLGA NPs were nontoxicity. The in vitro release profiles suggested that TOL-CS@PLGA NPs could release TOL in pH 7.4 phosphate buffer solution (PBS) at a sustained manner. Streptozotocin (STZ) was employed to build the diabetic rat models. The physiological changes in the islet β cells confirmed the obtaining of diabetic rats. After treatment by gavage, the TOL-CS@PLGA NPs showed an excellent hypoglycemic effect. Therefore, the TOL-CS@PLGA NPs had a potential application in oral delivery of TOL.