Siqueira Elis Regina Lima, Pinheiro Willie Oliveira, Aquino Victor Raul Romero, Coelho Breno Cunha Pinto, Bakuzis Andris Figueiroa, Azevedo Ricardo Bentes, Sousa Marcelo Henrique, Morais Paulo Cesar
Department of Genetics & Morphology, Institute of Biological Sciences, University of Brasília, Brasília DF 70910-900, Brazil.
Green Nanotechnology Group, Faculty of Ceilândia, University of Brasília, Brasília DF 72220-900, Brazil.
Nanomaterials (Basel). 2022 Aug 12;12(16):2760. doi: 10.3390/nano12162760.
This study investigated the fabrication of spherical gold shelled maghemite nanoparticles for use in magnetic hyperthermia (MHT) assays. A maghemite core (14 ± 3 nm) was used to fabricate two samples with different gold thicknesses, which presented gold (g)/maghemite (m) content ratios of 0.0376 and 0.0752. The samples were tested in MHT assays (temperature versus time) with varying frequencies (100-650 kHz) and field amplitudes (9-25 mT). The asymptotic temperatures (T∞) of the aqueous suspensions (40 mg Fe/mL) were found to be in the range of 59-77 °C (naked maghemite), 44-58 °C (g/m=0.0376) and 33-51 °C (g/m=0.0752). The MHT data revealed that T∞ could be successful controlled using the gold thickness and cover the range for cell apoptosis, thereby providing a new strategy for the safe use of MHT in practice. The highest SAR (specific absorption rate) value was achieved (75 kW/kg) using the thinner gold shell layer (334 kHz, 17 mT) and was roughly twenty times bigger than the best SAR value that has been reported for similar structures. Moreover, the time that was required to achieve T∞ could be modeled by changing the thermal conductivity of the shell layer and/or the shape/size of the structure. The MHT assays were pioneeringly modeled using a derived equation that was analytically identical to the Box-Lucas method (which was reported as phenomenological).
本研究调查了用于磁热疗（MHT）分析的球形金壳磁赤铁矿纳米颗粒的制备。使用磁赤铁矿核（14±3纳米）制备了两个具有不同金厚度的样品，其金（g）/磁赤铁矿（m）含量比分别为0.0376和0.0752。在MHT分析（温度与时间）中，对样品在不同频率（100 - 650千赫兹）和场强（9 - 25毫特斯拉）下进行了测试。发现水悬浮液（40毫克铁/毫升）的渐近温度（T∞）范围为59 - 77°C（裸磁赤铁矿）、44 - 58°C（g/m = 0.0376）和33 - 51°C（g/m = 0.0752）。MHT数据表明，通过金厚度可以成功控制T∞，使其覆盖细胞凋亡的范围，从而为MHT在实际中的安全应用提供了一种新策略。使用较薄的金壳层（334千赫兹，17毫特斯拉）时，实现了最高的比吸收率（SAR）值（75千瓦/千克），大约是已报道的类似结构最佳SAR值的20倍。此外，达到T∞所需的时间可以通过改变壳层的热导率和/或结构的形状/尺寸来建模。首次使用一个推导方程对MHT分析进行建模，该方程在分析上与Box - Lucas方法（据报道为唯象学方法）相同。
