Superparamagnetic iron oxide nanoparticles (SPIONs) and core-shell type nanoparticles, consisting of SPIONs coated with mesoporous silica and/or lipid, were synthesized and tested for their potential theranostic applications in drug delivery, magnetic hyperthermia and as a contrast agent. Transmission Electron Microscopy (TEM) confirmed the size of bare and coated SPIONs was in the range of 5-20 nm and 100-200 nm respectively. The superparamagnetic nature of all the prepared nanomaterials as indicated by Vibrating Sample Magnetometry (VSM) and their heating properties under an AC field confirm their potential for hyperthermia applications. Scanning Column Magnetometry (SCM) data showed that extrusion of bare-SPION (b-SPION) dispersions through a 100 nm polycarbonate membrane significantly improved the dispersion stability of the sample. No sedimentation was apparent after 18 hours compared to a pre-extrusion estimate of 43% settled at the bottom of the tube over the same time. Lipid coating also enhanced dispersion stability. Transversal relaxation time (T2) measurements for the nanoparticles, using a bench-top relaxometer, displayed a significantly lower value of 46 ms, with a narrow relaxation time distribution, for lipid silica coated SPIONs (Lip-SiSPIONs) as compared to that of 1316 ms for the b-SPIONs. Entrapment efficiency of the anticancer drug, Doxorubicin (DOX) for Lip-SPIONs was observed to be 35% which increased to 58% for Lip-SiSPIONs. Moreover, in-vitro cytotoxicity studies against human breast adenocarcinoma, MCF-7 cells showed that % cell viability increased from 57% for bSPIONs to 82% for Lip-SPIONs and to 87% for Lip-SiSPIONs. This suggests that silica and lipid coatings improve the biocompatibility of bSPIONs significantly and enhance the suitability of these particles as drug carriers. Hence, the magnetic nanomaterials prepared in this work have potential theranostic properties as a drug carrier for hyperthermia cancer therapy and also offer enhancement of contrast agent efficacy and a route to a significant increase in dispersion stability.

中文翻译：

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生物相容的超顺磁性核壳纳米颗粒可用于热疗药物释放和作为增强造影剂

合成了超顺磁性氧化铁纳米粒子 (SPION) 和核壳型纳米粒子，由涂有介孔二氧化硅和/或脂质的 SPION 组成，并测试了它们在药物递送、磁热疗和作为造影剂方面的潜在治疗诊断应用。透射电子显微镜 (TEM) 证实裸露和涂层 SPION 的尺寸分别在 5-20 nm 和 100-200 nm 的范围内。振动样品磁力计 (VSM) 表明所有制备的纳米材料的超顺磁性及其在交流场下的加热特性证实了它们在热疗应用中的潜力。扫描柱磁力仪 (SCM) 数据表明，通过 100 nm 聚碳酸酯膜挤出裸 SPION (b-SPION) 分散体显着提高了样品的分散稳定性。18 小时后没有明显的沉淀，而挤压前估计有 43% 的沉淀在同一时间沉淀在管子底部。脂质涂层还增强了分散稳定性。使用台式弛豫计对纳米颗粒的横向弛豫时间 (T2) 测量结果显示，与 1316 相比，脂质二氧化硅涂层的 SPION (Lip-SiSPION) 的值显着较低，为 46 ms，弛豫时间分布较窄b-SPION 的毫秒数。观察到抗癌药物多柔比星 (DOX) 对 Lip-SPIONs 的包埋效率为 35%，对于 Lip-SiSPIONs 增加到 58%。此外，针对人乳腺癌、MCF-7 细胞的体外细胞毒性研究表明，细胞活力百分比从 bSPION 的 57% 增加到 Lip-SPION 的 82% 和 Lip-SiSPION 的 87%。这表明二氧​​化硅和脂质涂层显着提高了 bSPIONs 的生物相容性，并增强了这些颗粒作为药物载体的适用性。因此，在这项工作中制备的磁性纳米材料作为热疗癌症治疗的药物载体具有潜在的治疗诊断特性，并且还提供增强造影剂功效和显着增加分散稳定性的途径。