Combination of ultrasound and newly synthesized magnetic nanocapsules affects the temperature profile of CT26 tumors in BALB/c mice

To investigate the effects of a combination of 3-MHz ultrasound waves with a new magnetic nanocapsule containing 5-fluorouracil (5-Fu) on the temperature profile of a mouse colon tumor (CT26) in BALB/c mice. Firstly, 5-Fu-loaded magnetic nanocapsules were synthesized using a multiple emulsion solvent evaporation procedure. Magnetic resonance imaging (MRI) was performed to evaluate the efficiency of nanocapsule localization in the tumor during magnetic drug targeting (MDT). Tumors were separately exposed to 3-MHz ultrasound waves at the intensities of 0.1, 0.3, 0.5, and 1 W/cm(2) for 10 min in the absence and presence of nanocapsules. The temperature of the tumor was recorded at 1-min intervals. The effective diameter of the nanocapsules was approximately 70 nm, and it was demonstrated that magnetic nanoparticles were well dispersed inside the nanocapsules. MRI confirmed that the magnetic nanocapsules were successfully targeted to the tumor after accomplishing MDT. Temperature change due to sonication of the tumor was strongly intensity dependent. Moreover, temperature-time curves revealed that the magnetic nanocapsules significantly affected the temperature rise profile of a sonicated tumor. Data presented in this study would be helpful to develop an ultrasound-mediated MDT procedure so that temperature changes of the tumor and its surrounding normal tissues may be controllable.