0 s−1 mM−1 and 265.7 s−1 mM−1, respectively (Figure 3). Figure 2 Preparation and characterization of Resovist-doxorubicin complex. Figure 3 Measurement of MR relaxivities. A) T2-weighted MR image of the phantom for relaxivity measurement. B) Plot of the inverse transverse relaxation times (1/T2) vs. Fe concentration.

The slopes indicate the specific relaxivity value (r2). Figure 4 summarizes the release pattern of doxorubicin from the complex. The driving force Sunitinib supplier for the doxorubicin conjugation is an ionic interaction, which is known to weaken as the temperature increases. The release test was performed at two different temperature, 37°C and 60°C, with a predetermined time profile to mimic the condition of hyperthermal therapy. As expected, sustained release of doxorubicin was observed at 37°C, whereas the release was accelerated at the elevated temperature. Figure 4 The in vitro release pattern of doxorubicin from the Resovist-doxorubicin complex. Tumor temperature measurement

The tumor temperature in group C and D rapidly increased to approximately 42°C within 5 minutes and then remained stable for 20 minutes, whereas in group A and B did not increased significantly (Figure 5A). The average values of tumor temperature change 25 minutes after initiation of hyperthermia were 1.88 ± 0.21°C in group A, 0.96 ± 1.05°C in group B, 7.93 ± 1.99°C in group C, and 8.95 ± 1.31°C in group D (Figure 5B). Group C and D exhibited a significantly higher temperature in the tumors than group A or B (p < 0.05). The exact p-values obtained from comparisons between groups are summarized Sorafenib chemical structure in Table 1. The rectal temperatures in all groups remained stable near the baseline values during the treatment. Figure 5 The temperature

changes of the tumors. A) Plot of the temperature change curve during heating versus time (blue: group A, red: group B, green: group C, purple: group D). B) The mean temperature Interleukin-3 receptor changes of the tumors (t/t0) during treatment. The error bars represent the standard deviations (*P < 0.05, compared to group A). Table 1 Comparisons of the temperature changes in tumor, RSIs of BLI at day 14 post-treatment, and apoptosis rates between groups (* p  < 0.01, ** p  < 0.05)   Group B vs. C Group B vs. D Group C vs. D Temperature changes 0.009* 0.009* 0.465 RSIs of BLI 0.834 0.047** 0.009* Apoptosis rates 0.675 0.028** 0.008* Each number in the table indicates a p-value obtained by Mann–Whitney test. Bioluminescence imaging findings In group A receiving normal saline for control, the RSI of BLI increased continuously over the follow-up period reflecting active tumor growth (2.23 ± 1.14). In group B, the RSI of BLI slightly decreased gradually until day 14 post-treatment (0.94 ± 0.47), which suggests that the cytotoxic effect of doxorubicin works on the tumor slowly (Figure 6A, B).