Novel polyelectrolyte complexes based on poly(methacrylic acid)-bis(2-aminopropyl)poly(ethylene glycol) for oral protein delivery

In the present investigation a simple and effective strategy was employed for the development of pH-sensitive self-assembling microparticles based on poly(methacrylic acid) (PMAA)-bis(2-aminopropyl)poly(ethylene glycol) (APEG), and their efficiency in oral protein delivery was evaluated. An inter-ionic gelation process was employed for the preparation of microparticles and particles were obtained spontaneously during the process without using any surfactants or stabilizers. Particle size analysis was carried out to measure average particle size and surface morphology was evaluated using scanning electron microscopy (SEM). Bovine serum albumin (BSA) was incorporated onto these microparticles to evaluate the loading and release properties of the matrix. PMAA-APEG microparticles displayed pH responsive release profile, as less than 10% of encapsulated BSA was released at pH 1.2 in 2 h and more than 80% of loaded protein was released within 3 h at pH 7.4. Carboxymethyl beta-cyclodextrin (CM beta CD)-insulin non-covalent inclusion complex was prepared to enhance the stability of insulin formulations and complex formation was analyzed by fluorescence spectroscopic studies. CM beta CD-complexed insulin was encapsulated into PMAA-APEG microparticles by a diffusion filling method and biological activity of entrapped insulin was evaluated using an ELISA. Finally mucoadhesive studies of PMAA-APEG microparticles were carried out on freshly excised rat intestinal mucosa at neutral pH to establish the adhesive nature of the material.