Microgel-Based Thermosensitive MRI Contrast Agent.
Microgel-Based Thermosensitive MRI Contrast Agent.
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DOI：
10.1021/acsmacrolett.5b00058
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发表时间：
2015-04
影响因子：
5.8
通讯作者：
Xinwei Zheng;J. Qian;F. Tang;Zengrong Wang;Chunyan Cao;K. Zhong
中科院分区：
文献类型：
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作者：
Xinwei Zheng;J. Qian;F. Tang;Zengrong Wang;Chunyan Cao;K. Zhong
无创监测细微的温度变化仍然是磁共振成像（MRI）的一个挑战。以四（3-乙烯基苯基）锰卟啉为核，N-异丙基丙烯酰胺（NIPAM）或N-异丙基甲基丙烯酰胺（NIPMAM）为单体，N，N '-亚甲基双丙烯酰胺（MBA）为交联剂，合成了一种基于温敏微凝胶的温敏造影剂。NIPAM掺入的微凝胶（M-1）的体积在其低临界溶解温度（LCST，29-33 °C）附近急剧减小，而NIPMAM掺入的微凝胶（M-2）的体积逐渐减小。M-1的MR纵向弛豫率（r1）增强（44%），而M-2的相应变化要小得多。在没有MBA交联剂的情况下，进一步优化M-1的合成，以获得M-3，其显示r1在其LCST附近增加67%。我们的研究结果表明，纵向弛豫强烈调制微凝胶体积变化周围的LCST，导致r1显着增加。这种新型的热敏微凝胶可以潜在地应用于使用MRI方法监测微小的温度变化。
Monitoring subtle temperature changes noninvasively remains a challenge for magnetic resonance imaging (MRI). A temperature-sensitive contrast agent based on thermosensitive microgel is proposed and synthesized using a manganese tetra(3-vinylphenyl) porphyrin core reacting with N-isopropylacrylamide (NIPAM) or N-isopropylmethacrylamide (NIPMAM) monomers and N,N'-methylenebis(acrylamide) (MBA) cross-linkers. The volume of the NIPAM-incorporated microgel (M-1) decreased sharply around its lower critical solution temperature (LCST, 29-33 °C), whereas the volume of the NIPMAM-incorporated microgel (M-2) decreased gradually. MR longitudinal relaxivity (r1) enhancement (44%) was obtained for M-1, while the corresponding change for M-2 was much smaller. M-1 was further optimized in synthesis without an MBA cross-linker to obtain M-3 which showed a 67% increase in r1 around its LCST. Our results suggested that the longitudinal relaxivity is strongly modulated by microgel volume change around the LCST, leading to a significant increase in r1. This novel thermally sensitive microgel could potentially be applied to monitor small temperature changes using MRI methods.