Vascular embolization has exhibited increasing significance in treatment of terminal cancer. In order to achieve better embolic effects, magnetic polyvinyl alcohol hydrogel microspheres were synthesized for magnetic field-controlled vascular embolization.;Inverse suspension crosslinking method was adopted to synthesize the magnetic hydrogel microspheres by loading magnetic nanoparticles inside. The magnetic property, CT angiography, drug release, and magnetothermal performance were characterized in vitro, respectively. The fluidity of microspheres was also showed by simulation and experiment in vitro.;The microspheres were shown to have capability of drug loading, CT imaging, and magnetothermal behavior. Both the simulated and the experimental results exhibited that the microspheres can be controlled to aggregate in the fluid in the presence of magnetic field.;The magnetic hydrogel microspheres exhibited the specific fluidity-like iodized oil, but were able to form solid embolus. Because of the advantages of this novel material, it is expected to get extensive application in the clinic embolotherapy.
血管栓塞在晚期癌症的治疗中具有越来越重要的意义。为了获得更好的栓塞效果，合成了磁性聚乙烯醇水凝胶微球，用于磁场控制的血管栓塞;采用反相悬浮交联法，通过内装磁性纳米颗粒合成磁性水凝胶微球。在体外分别对磁性能、CT血管造影、药物释放和磁热性能进行了表征。体外模拟和实验结果表明，该微球具有良好的载药能力、CT成像能力和磁热性能。模拟和实验结果均表明，在磁场作用下，微球可在液体中聚集;磁水凝胶微球表现出特定的类流状碘化油，但能形成固体栓子。由于这种新型材料的优点，有望在临床上得到广泛的应用。
【1】Qiu, Shuang,Ge, Nai J.,Sun, Dong K., et al.Synthesis and Characterization of Magnetic Polyvinyl Alcohol (PVA) Hydrogel Microspheres for the Embolization of Blood Vessel[J].IEEE Transactions on Biomedical Engineering,2016,63(4):730-736.
Biodegradable polymeric microspheres can be used to deliver drugs through controlled rate and targeted processes. The drug is released from the particles by drug leaching or degradation of the polymeric matrix. Crystallinity can play a very important role in the degradation of polymeric matrixes; it can affect the drug-release rate, especially in chemoembolization. Most commercial embolic agents have a low degree of crystallinity, and the correlation between the drug-delivery rate and the degree of crystallinity is not fully understood. This study presents the appropriated synthesis conditions for the preparation of highly crystalline poly(vinyl alcohol) and poly(vinyl alcohol)/poly(vinyl acetate) microspheres and physicochemical characterizations by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and cross-polarization/magic angle spinning nuclear magnetic resonance.
生物可降解聚合物微球可以通过控制速率和靶向过程来传递药物。药物通过药物浸出或聚合物基质降解从颗粒中释放出来。结晶度在聚合物基体的降解中起着非常重要的作用;它可以影响药物的释放速度，特别是在化疗栓塞。大多数商用栓塞剂结晶度较低，而药物递送率与结晶度之间的相关性尚未得到充分了解。本研究为高结晶聚(乙烯醇)和聚(乙烯醇)/聚(醋酸乙烯酯)微球的制备提供了适宜的合成条件，并通过扫描电子显微镜、x射线衍射、差示扫描量热法、交叉极化/幻角自旋核磁共振等手段进行了物化表征。
【2】Semenzim, V.L.,Basso, G.G.,Da Silva, D.A., et al.Synthesis and characterization of novel, highly crystalline polyvinyl alcohol) microspheres for chemoembolization therapy[J].Journal of Applied Polymer Science,2011,121(3):1417-1423.
The aim of this work was to develop long-term radiopaque microspheres (LRMs) by entrapping lipiodol in biocompatible polyvinyl alcohol with multiple emulsions chemical crosslinking method. The high content of lipiodol (0.366thinsp;g/mL) was hardly released from LRMs in vitro and the radiopacity could maintain at least 3 months after subcutaneous injection in mice without weakening. A series of tests was performed to evaluate the feasibility of LRMs for embolization. LRMs were proved to be smooth, spherical, and well dispersed with diameter range of 100–1200thinsp;mu;m. Youngs modulus of LRMs was 55.39thinsp;plusmn;thinsp;9.10 kPa and LRMs could be easily delivered through catheter without aggregating or clogging. No toxicity of LRMs was found to mouse L929 fibroblasts cells and only moderate inflammatory in surrounding tissue of mice was found after subcutaneous injection of LRMs. After LRMs were embolized in renal artery of a rabbit, the distribution and radiopacity of LRMs in vivo were easily detectable by X-ray fluoroscopy and computed tomography (CT) imaging, respectively. More accurate distribution of LRMs in embolized kidney and vessels could be detected by high-revolution visualization of micro-CT ex vivo. In conclusion, the LRMs were proved to be biocompatible and provide long-term radiopacity with good physical and mechanical properties for embolization.
本工作的目的是开发长期辐射不透明微球(LRMs)，通过多乳液化学交联法将碘油包埋在生物相容性聚乙烯醇中。LRMs在体外难以释放出高含量的碘油(0.366 g/mL)，经皮下注射后小鼠的放射不透明度至少可维持3个月而不减弱。我们进行了一系列的试验来评估LRMs栓塞的可行性。lrm被证明是光滑,球形,直径范围100 - 1200mu;m分散。LRMs的杨氏模量为55.39plusmn;9.10 kPa, LRMs可通过导管顺利输送，无聚集或堵塞。LRMs对小鼠L929成纤维细胞无毒性作用，皮下注射LRMs后小鼠周围组织仅有中度炎症反应。在兔肾动脉栓塞LRMs后，LRMs在体内的分布和放射不透明度分别可以通过x线透视和计算机断层扫描(CT)检查出来。微ct高转位显示能更准确地显示LRMs在栓塞的肾脏和血管中的分布。总之，经证实LRMs具有良好的生物相容性，为栓塞治疗提供了良好的物理和机械性能。
【3】Meng, Wen-Jing,Lu, Xiao-Jing,Wang, Huan, et al.Preparation and evaluation of biocompatible long-term radiopaque microspheres based on polyvinyl alcohol and lipiodol for embolization[J].Journal of biomaterials applications,2015,30(2):133-146.
