Gene expression is used extensively to describe cellular characteristics and behaviors; however, most methods of assessing gene expression are unsuitable for living samples, requiring destructive processes such as fixation or lysis. Recently, molecular beacons have become a viable tool for live-cell imaging of mRNA molecules in situ. Historically, beacon-mediated imaging has been limited to fluorescence-based approaches. We propose the design and synthesis of a novel molecular beacon for magnetic resonance detection of any desired target nucleotide sequence. The biologically compatible synthesis incorporates commonly used bioconjugation reactions in aqueous conditions and is accessible for laboratories without extensive synthesis capabilities. The resulting beacon uses fluorine (¹⁹F) as a reporter, which is broadened, or turned “off”, via paramagnetic relaxation enhancement from a stabilized nitroxide radical spin label when the beacon is not bound to its nucleic acid target. Therefore, the ¹⁹F NMR signal of the beacon is quenched in its hairpin conformation when the spin label and the ¹⁹F substituent are held in proximity, but the signal is recovered upon beacon hybridization to its specific complementary nucleotide sequence by physical separation of the radical from the ¹⁹F reporter. This study establishes a path for magnetic resonance-based assessment of specific mRNA expression, providing new possibilities for applying molecular beacon technology in living systems.

中文翻译：

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磁性活性¹⁹ F分子信标的合成与表征

基因表达被广泛用于描述细胞特征和行为。但是，大多数评估基因表达的方法都不适合活体样品，需要破坏性过程，例如固定或裂解。最近，分子信标已成为用于mRNA分子原位活细胞成像的可行工具。历史上，信标介导的成像仅限于基于荧光的方法。我们提出了一种新颖的分子信标的设计和合成，用于磁共振检测任何所需的靶核苷酸序列。生物相容性合成法结合了水性条件下常用的生物共轭反应，没有广泛的合成能力的实验室也可以使用。生成的信标使用氟（¹⁹F）作为报告基因，当信标未与其核酸靶标结合时，通过稳定的一氧化氮自由基自旋标记物的顺磁弛豫增强作用而被拓宽或“关闭”。因此，当旋转标记和¹⁹ F取代基保持靠近时，信标的¹⁹ F NMR信号在其发夹构象中被淬灭，但是在信标杂交至其特定互补核苷酸序列后，通过自由基的物理分离可恢复该信号。来自¹⁹楼的记者。这项研究为基于磁共振的特定mRNA表达评估提供了一条途径，为在生命系统中应用分子信标技术提供了新的可能性。