Necrosis of carcinoma cells using Co/sub 1-x/Ni/sub x/Fe/sub 2/O/sub 4/ and Ba/sub 1-x/Sr/sub x/Fe/sub 12/O/sub 19/ ferrites under alternating magnetic field

The purpose of this study was to investigate the cell necrosis by the hysteric heating of Co/sub 1-x/Ni/sub x/Fe/sub 2/O/sub 4/ and Ba/sub 1-x/Sr/sub x/Fe/sub 12/O/sub 19/ ferrites under external magnetic field with respect to applications in hyperthermic cancer treatments. Co/sub 1-x/Ni/sub x/Fe/sub 2/O/sub 4/ and Ba/sub 1-x/Sr/sub x/Fe/sub 12/O/sub 19/ ferrites were synthesized by a sol-gel process. Variation of the temperature as a result of hysteresis heating was measured as a function of the exposure time to the external alternating magnetic field at frequencies of 0.1 /spl sim/ 15 MHz. A human squamous cell carcinoma KB cell line was selected to determine the effect of the synthesized ferrites on the destruction of carcinoma cells in vitro using a methylthiazol tetrazolium bromide (MTT) method. When a CoFe/sub 2/O/sub 4/ disc was placed in 0.2 ml of distilled water, the greatest temperature change (/spl Delta/T=29.3/spl deg/C) was observed. More than half of the malignant carcinoma cells were dead after being exposed to the 7-MHz ac magnetic field for 1 h by CoFe/sub 2/O/sub 4/ ferrites, while normal cells survived more than 60% of the time.