Stainless Steel Hollow Microspheres for Arterial Embolization Hyperthermia

Abstract

To find a novel microscaled mediator suitable for arterial embolization hyperthermia (AEH). Stainless steel microspheres including both hollow (H1) and solid ones (S1) were produced with dispersing molten steel stream by water jet. Theoretically analyzing the power absorption of them in alternating magnetic field revealed that larger size and smaller permeability led to more heat generation. Higher field intensity and frequency also improved the heating power. Given the same condition, heating power per unit mass was greater in hollow microsphere than solid one. Microscopic observations of H1 and S1 were conducted along with particle size distribution, magnetization curve and heating power measurement. In vivo heating test, in vitro hyperthermia test and in vitro biocompatibility test were conducted for the finally selected mediator H1. The measured heating power of H1 and S1 met the theoretical values in low intensity field, but was considerably below expectation in strong field. Power density of H1 was clearly greater than that of S1 as theoretically predicted. The temperature of a rabbit ear in magnetic field injected with H1 maintained 50 °C for 10 min. In vitro hyperthermia test showed its outstanding treatment effectiveness for cancer cells. Cytotoxicity of H1 was categorized as Grade I, which is regarded as no cytotoxicity. Stainless steel hollow microsphere H1 was a promising mediator for AEH for its high efficiency in heating tumor region and killing cancer cells as well as good biocompatibility.

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