Specific absorption rate dependence on temperature in magnetic field hyperthermia measured by dynamic hysteresis losses (ac magnetometry).

摘要: Magnetic nanoparticles (NPs) are intensively studied for their potential use magnetic hyperthermia, a treatment that has passed phase II clinical trial against severe brain cancer (glioblastoma) at the end of 2011. Their heating power, characterized by 'specific absorption rate (SAR)', is often considered temperature independent in literature, mainly because difficulties arise from measurement methodology. Using dynamic magnetometer presented recent paper, we measure here thermal dependence SAR superparamagnetic iron oxide (maghemite) NPs four different size-ranges corresponding to mean diameters around 12 nm, 14 15 nm and 16 nm. The article reports parametrical study extending 10 60 °C temperature, 75 1031 kHz frequency, 2 24 kA m(-1) field strength. It was observed values smaller decrease with whereas larger sample (16 nm) increase temperature. measured variation frequency dependent. This behaviour fully explained within scope linear response theory based on Neel Brown relaxation processes, using measurements specific magnetization anisotropy constant. A good quantitative agreement between experimental theoretical confirmed tri-dimensional space uses as coordinates strength,