Magnetic resonance imaging using fluorinated contrast agents (¹⁹F MRI) enables to achive highcontrast in images due to the negligible fluorine background in living tissues. In this pilot study, we developed new biocompatible, temperature-responsive, and easily synthesized polymeric nanogels containing a sufficient concentration of magnetically equivalent fluorine atoms for ¹⁹F MRI purposes. The structure of the nanogels is based on amphiphilic copolymers containing two blocks, a hydrophilic poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) or poly(2-methyl-2-oxazoline) (PMeOx) block, and a thermoresponsive poly[N(2,2difluoroethyl)acrylamide] (PDFEA) block. The thermoresponsive properties of the PDFEA block allow us to control the process of nanogel self-assembly upon its heating in an aqueous solution. Particle size depends on the copolymer composition, and the most promising copolymers with longer thermoresponsive blocks form nanogels of suitable size for angiogenesis imaging or the labeling of cells (approximately 120 nm). The in vitro¹⁹F MRI experiments reveal good sensitivity of the copolymer contrast agents, while the nanogels were proven to be noncytotoxic for several cell lines.

中文翻译：

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自组装的热响应聚合物纳米凝胶用于¹⁹ F MR成像

由于活组织中的氟背景可忽略不计，使用氟化造影剂的磁共振成像（¹⁹ F MRI）可以实现图像的高对比度。在这项前期研究中，我们开发了新型的生物相容性，温度响应性且易于合成的聚合物纳米凝胶，其中包含足够浓度的磁性等效氟原子，可用于¹⁹ F MRI。纳米凝胶的结构基于两亲共聚物，其中包含两个嵌段，即亲水性聚[ N-（2-羟丙基）甲基丙烯酰胺]（PHPMA）或聚（2-甲基-2-恶唑啉）（PMeOx）嵌段，以及热响应性聚[ N（2,2-二氟乙基）丙烯酰胺]（PDFEA）嵌段。PDFEA嵌段的热响应特性使我们能够控制纳米凝胶在水溶液中加热后的自组装过程。粒度取决于共聚物的组成，具有更长的热响应性嵌段的最有希望的共聚物会形成纳米凝胶，其尺寸适合血管生成成像或细胞标记（约120 nm）。在体外¹⁹ ˚FMRI实验揭示了所述共聚物的造影剂的良好的灵敏度，而纳米凝胶被证明是无细胞毒性的几种细胞系。