Preparation and characterization of 5-fluorouracil pH-sensitive niosome and its tumor-targeted evaluation: in vitro and in vivo.

The purpose of this study was to investigate preparation, characterization and tumor-targeted effect of pH-sensitive niosomes, composed of a nonionic surfactant mixed with cholesteryl hemisuccinate (CHEMS), a derivative of cholesterol (CHOL), as a pH-sensitive molecule. CHEMS was synthesized with CHOL and succinic acid, the structure of which was analyzed by Mass spectrometry (MS) and ¹H Nuclear magnetic resonance (¹H NMR) spectrum. Niosomes were prepared via film hydration-probe ultrasound method. Both normal niosomes and pH-sensitive niosomes showed spherical morphology under transmission electron microscope (TEM) with a average particle sizes of 172 ± 6.2 nm and 153 ± 4.7 nm, respectively. The thermotropic behavior, structure changes and interaction of 5-fluorouracil (5-Fu) with other materials were characterized by differential scanning calorimetry (DSC), and the disappearance of the melting peak of drug revealed the fact that drug was encapsulated in niosomes. Bulk-equilibrium reverse-dialysis method was chosen to investigate the behavior of drug release from normal niosomes and pH-sensitive niosomes in different pH medium, and the results showed that the noisome containing CHEMS had a pH-sensitive property. Tumor-targeted effect was proved by the fact that pH-sensitive niosomes showed a remarkable high concentration in tumor site of the mice transplanted with tumor cell.