pH-responsive hydrogel microparticles as intelligent delivery carriers for α-MSH antagonists

For a first step in the development of an intelligent delivery system for a nonapeptide as an α-MSH antagonist, pH-responsive P(MAA-co-EGMA) hydrogel microparticles were prepared and their feasibility as intelligent delivery carriers was evaluated. There was a drastic change in the swelling ratio of P(MAA-co-EGMA) microparticles at a pH of around 5 and as the MAA amount in the hydrogel increased, the swelling ratio increased at a pH above 5. The loading efficiency of the nonapeptide at pH 7 increased with the amount of Methacrylic acid (MAA) in the hydrogel and at pH 2, where the electrostatic attraction was greatest, a high loading efficiency was not obtained because of the low swelling ratio of the hydrogel. The P(MAA-co-EGMA) microparticles demonstrated a pH-sensitive release behavior for the nonapeptide. In addition, the P(MAA-co-EGMA) microparticles showed a protective ability for the nonapeptide and preserved the stability of the nonapeptide.