DECREASING SIZE OF RADIOSENSITIVE CAPSULES FROM MICRO TO NANO, AND ITS INCREASED ANTITUMOR EFFECT AND DECREASING ADVERSE EFFECT

Abstract

We have been developing microcapsules that release anticancer drug with response to radiation. We attempted to decrease the diameter of capsules. Then, two categories were tested in VIVO in C3He mice: (1) the antitumor effect in combination with radiation and subcutaneously injected nanocapsules, (2) the kidnetics of nanocapsules when they were injected intravenously. Microcapsules were produced by spraying a mixture of 3.0 % hyaluronic acid, 2.0 % alginate, 3.0 % H2O2, and 0.3 mmol carboplatin (Pt containing anticancer drug) onto a mixture of vibrated 0.3 mol FeCl 2 and 0.15 mol CaCl 2. The antitumor effect was measured by measuring tumor diameter every day. The kinetics of microcapsules were expressed as the numbers of capsules in 5 views (25 × 25 μm) of micro PIXE camera and Pt concentration of quantiative PIXE. The generated microcapsules 752 ± 64 nm, which were significantly downsized relative to previous capsules. The accumulations of capsules in lungs, liver, and kidneys were decreased by downsizing, whereas those of tumors were increased. By adjusting Pt concentration in tumor, there were no significant differences in antitumor effect between not downsized and downsized microcapsules with combination with radiation. Decreased trapping of downsized microcapsules to lungs, liver, and kidneys, also increased trapping in tumors will lead to new targeted chemoradiotherapy via intravenous injection of microcapsules.