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Objective To develop an safety,injectable and biodegradable material using calcium phosphate cement containing Fe3O4 nanoparticles for minimally invasive magnetic hyperthermia ablation of tumor.Methods Magnetic calcium phosphate cement (MCPC) with different weights and iron contents were prepared and characterized including morphology ,washout resistance ability, injectability, degradability, and exotherm during the setting reaction.Under alternating magnetic field,the heating efficiency of the MCPC in vitro with PBS and in excised bovine liver were evaluated by the measurement of temperature, and ablation efficiency in bovine liver and MB231 human breast cancer xenograft by ablated tissue volume, and further confirmed by pathology examination.Meanwhile, the echo and imaging of the MCPC in and after setting reaction were monitored by real time ultrasound.Results CPC was porous and the Fe3O4 nanoparticles were uniformly distributed within CPC.The 5% and 10% MCPC were resistant to washout, while the 15% MCPC disintegrated.The injectability increased with the iron content with an injectable percentage (90.67±1.53)% for 10% MCPC.The degradability increased with time and the increase in iron content.After 68 days, the weight loss were (24.23 ±0.02)%, (32.62 ±0.03)%, (37.38 ±0.03)% respectively for 0.5 g CPC, 5% MCPC and 10% MCPC.When exposed to the alternating magnetic field, the MCPC could quickly generate a lot of heat, and the temperature of PBS and live was increased with the MCPC weight, iron content and time.The ablated liver tissue volumes of 0.36 g 10% MCPC were (0.2±0.03)cm3, (1.01±0.07)cm3, and (1.96±0.19)cm3 respectively at the time point of 60 s, 180 s and 300 s.In vivo experiment,the MCPC could be directly injected into the core position of tumors under the guidance of US imaging.The formed MCPC was well restricted within the tumor tissues without the occurrence of leakage.The breast tumors were completely ablated by 0.36g of 10% injectable MCPC after 180 s induction heating.HE staining showed that the ablated tumor xenograft were coagulation necrosis.After two weeks, necrotic tissue separated from the nude mice and fell off.Conclusion We have developed a safe,injectable,and biodegradation material using CPC containing Fe3O4 nanoparticles for minimally invasive magnetic ablation of breast tumor.