超音波振盪對四氧化三鐵磁性奈米粒子之加熱比吸收率影響之研究
1 蔡長書 2 陳弘一
1 慈濟技術學院放射技術系暨放射醫學科學研究所
2 慈濟技術學院放射醫學科學研究所
提要
四氧化三鐵磁性奈米粒子目前已被廣泛的運用在生物醫學的研究領域上，如腫瘤治療、靶向藥劑、基因篩選或細胞分離、核磁影像檢測等。藉由外部交流磁場加熱磁性奈米粒子促使腫瘤組織溫度提高超過43℃以上，破壞腫瘤之新生血管，可有效抑制其營養供給，來達到治療腫瘤之成效，並且無侵襲性之問題，臨床上更可作為化學治療與放射治療之輔助療法。然而，奈米粒子表面效應大，產物材料極易產生團聚（aggregation）現象，嚴重影響材料品質之功能與特性，包含加熱效率、粒徑分佈、超順磁性等，導致無法有效運用在生物醫學方面之研究與推廣，尤其嚴重影響臨床腫瘤治療之熱效應之成效。為克服奈米物質分子之團聚現象，本研究嘗試使用超音波震盪法，並以磁性奈米粒子比吸收率值作為加熱效率成效指標之評估，探討超音波震盪對磁性奈米粒子材料品質及其加熱效率之影響。由實驗結果可獲得以下幾項初步之結論：一、四氧化三鐵磁性奈米粒子樣品重覆加熱及重覆振盪30 秒以上，可讓磁性奈米粒子有充分時間均勻分散，83 % 實驗樣品可獲80.0 ± 10.6 W/g 以上穩定之 SAR 值。二、加熱前震盪之樣品，大部分可於30 秒內超過43℃，而經加熱後不震盪之樣品，其所得到之SAR 值前後差異相當大（p-value＜0.01），極有可能為樣品經加熱後，又趨於團聚，而導致再次加熱時，加熱效率有所下降，得到與前者相反之結果，如比值1：1 莫耳濃度比值之Fe2+：Fe3+，其SAR 值由65.5±5.5 降至47.6 ± 4.3 W/g。三、加熱的同時，亦會造成粒子之團聚，因此須於每次加熱前經超音波震盪超過5 分鐘，不論Fe2+：Fe3+ 莫耳濃度比值，皆可獲高於82.2 ± 11.4 W/g 之SAR 值。
關鍵字：磁性奈米粒子、熱治療、團聚現象、超音波震盪、比吸收率
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Study on the specific adsorption rate of Fe3O4 magnetic nano-particles by ultrasonic shaking
1 Chang-Shu Tsai 2 Hong-Yi Chen
1 Department of Radiological Technology and Institute of Radiological Science, Tzu-Chi College of Technology
2 Institute of Radiological Science, Tzu-Chi College of Technology
Abstract
Fe3O4 magnetic nano-particles are extensively studied in bio-medicine field such as tumor therapy, target drug, gene screen, cell separation and magnetic resonance imaging (MRI). Hyperthermia is adjuvant treatment for chemical and radiation therapy. Besides, there is no invasion problems that the treatments may increase tumor temperature about 43 ℃ or more by external alternating magnetic field to heat the nanoparticles, and destroy tumor
angiogenesis, effectively inhibited its nutritional supply, which achieve the effective treatment to the cancer. However, it must be pointed that magnetic nano-particles are easy to form aggregation due to its large atom surfacial effect. It will significantly affect nano-material’s function and quality, for example, heat efficiency, particle size, superparamagnetic, and hyperthermia promotion etc. In this study, we used ultrasonic shaking method to improve
the defect and choose the specific adsorption rate of Fe3O4 magnetic nano-particle as indicators . According to the experimental results , the SAR value of 83 % nano-particle materials are above 80.0 ± 10.6 W/g，when using ultrasonic shaking repeatly for over 30 seconds duration after heating. The nano-particle materials raised temperature to 43℃ by ultrasonic shaking for 30 seconds periods before heating. The SAR value will decrease
without ultrasonic shaking after heating. It may produce aggregation effect simultaneously when the nano-particle materials were heated. Regardless of the molar ratio of Fe2+：Fe3+ , the SAR values are all above 82.2 ± 11.4 W/g by ultrasonic shaking for 5 mins before heating.
Keywords：Fe3O4 magnetic nanoparticles, hyperthermia, aggregation, ultrasonic shaking, specific adsorption rate