Effects of pH-sensitive nanoparticles prepared with different polymers on the distribution, adhesion and transition of Rhodamine 6G in the gut of rats.

To investigate the effect of different enteric polymers on the characteristics of pH-sensitive nanoparticles, Rhodamine 6G (Rho) was incorporated in various pH-sensitive nanoparticles. The different patterns of pH-dependent release profiles were observed, although some polymers have the same dissolving pH. The distribution, adhesion and transition of different nanoparticles in rat gut showed significant difference, closely related to the release characteristics of nanoparticles, and their release behaviour are dependent on the dissolving pH and the structure of the polymers, as well as the drug property.Most nanoparticle formulations decreased the distribution and adhesion of Rho in the stomach but increased these values in the intestine. The nanocarriers also control the drug release sites and release rate in the GI tract. In conclusion, pH-sensitive nanoparticles seem favourable for drug absorption and it is important to choose the proper materials to obtain the suitable characteristics for the oral pH-sensitive nanoparticles.