In this study, a high-efficiency superparamagnetic drug delivery system was developed for preclinical treatment of bladder cancer in small animals. Two types of nanoparticles with magnetic particle imaging (MPI) capability, i.e., single- and multi-core superparamagnetic iron oxide nanoparticles (SPIONs), were selected and coupled with bladder anti-tumor drugs by a covalent coupling scheme. Owing to the minimal particle size, magnetic field strengths of 270 mT with a gradient of 3.2 T/m and 260 mT with a gradient of 3.7 T/m were found to be necessary to reach an average velocity of 2 mm/s for single- and multi-core SPIONs, respectively. To achieve this, a method of constructing an in vitro magnetic field for drug delivery was developed based on hollow multi-coils arranged coaxially in close rows, and magnetic field simulation was used to study the laws of the influence of the coil structure and parameters on the magnetic field. Using this method, a magnetic drug delivery system of single-core SPIONs was developed for rabbit bladder therapy. The delivery system consisted of three coaxially and equidistantly arranged coils with an inner diameter of Φ50 mm, radial height of 85 mm, and width of 15 mm that were positioned in close proximity to each other. CCK8 experimental results showed that the three types of drug-coupled SPION killed tumor cells effectively. By adjusting the axial and radial positions of the rabbit bladder within the inner hole of the delivery coil structure, the magnetic drugs injected could undergo two-dimensional delivery motions and were delivered and aggregated to the specified target location within 12 s, with an aggregation range of about 5 mm × 5 mm. In addition, the SPION distribution before and after delivery was imaged using a home-made open-bore MPI system that could realistically reflect the physical state. This study contributes to the development of local, rapid, and precise drug delivery and the visualization of this process during cancer therapy, and further research on MPI/delivery synchronization technology is planned for the future.

中文翻译：

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开发具有MPI成像能力的高效超顺磁性药物递送系统

在这项研究中，开发了一种高效超顺磁药物递送系统，用于小动物膀胱癌的临床前治疗。选择两种具有磁性粒子成像（MPI）能力的纳米颗粒，即单核和多核超顺磁性氧化铁纳米颗粒（SPION），并通过共价偶联方案与膀胱抗肿瘤药物偶联。由于颗粒尺寸最小，需要 270 mT（梯度为 3.2 T/m）的磁场强度和 260 mT（梯度为 3.7 T/m）的磁场强度才能达到单粒子平均速度 2 mm/s。和多核 SPION。为了实现这一点，需要一种构建方法体外基于同轴紧密排排列的空心多线圈开发了用于药物输送的磁场，并通过磁场模拟研究了线圈结构和参数对磁场的影响规律。利用这种方法，开发了一种用于兔膀胱治疗的单核 SPION 磁性药物递送系统。输送系统由三个同轴等距排列的线圈组成，线圈的内径为Φ50毫米，径向高度为85毫米，宽度为15毫米，并且彼此靠近。 CCK8实验结果表明，三种药物偶联的SPION均能有效杀伤肿瘤细胞。通过调整输送线圈结构内孔内兔膀胱的轴向和径向位置，注射的磁性药物可以进行二维输送运动，并在12 s内输送并聚集到指定的目标位置，聚集范围约5毫米×5毫米。此外，使用自制的开孔 MPI 系统对分娩前后的 SPION 分布进行成像，可以真实地反映物理状态。这项研究有助于发展局部、快速、精确的药物输送以及癌症治疗过程中这一过程的可视化，并且计划未来对 MPI/输送同步技术进行进一步的研究。