Overview and progress of X-nuclei magnetic resonance imaging in biomedical studies

Proton nuclear(^(1)H)is the observed nucleus on which most magnetic resonance imaging(MRI)applications depend.Most traditional^(1)H MRI can provide structural and functional information about organisms,while various non-proton nuclei(X-nuclei)MRI can provide more metabolic information.However,due to the relatively poor signal-to-noise ratio(SNR)of X-nuclei MRI,their applications are quite rare compared to^(1)H.Benefit from the rapid developments of MRI hardware and software technologies,X-nuclei MRI has recently attracted increasing interests in biomedical research.This review firstly introduces some current methods to improve the SNR of X-nuclei MRI.Secondly,this review describes biomedical applications of X-nuclei MRI,especially focusing on the current use of X-nuclei(^(13)C,^(17)O,^(19)F,^(23)Na and^(31)P)MRI to study related diseases in different organs,including the brain,liver,kidney,heart and bone.Finally,perspectives studies on X-nuclei imaging and its potential applications are described in biomedical research.

Multicolor^(19)F magnetic resonance imaging:A promising medical technique for in vivo visualization of multiple biological targets

Driven by the needs of precision medicine,current imaging techniques are under continuous development to offer more accurate and comprehensive information beyond traditional macroscopic anatomical images.Multispectral color-coded(multicolor)^(19)F magnetic resonance imaging(MRI)is receiving increasing attention owing to its capability for visualizing quantitative and multiplexed molecular information during various biological processes.The chemical design and preparation of^(19)F probes lie at the core of multicolor^(19)F MRI since their performance dominates the accomplishment of this technique.Herein,the working principles of multicolor^(19)F MRI are briefly introduced.Recent progress on multicolor^(19)F MRI probes for simultaneous in vivo visualization of multiple biological targets is summarized.Finally,current challenges and potential solutions in this fast-developing field are discussed.

Organic Nanoprobes for Fluorescence and ^19F Magnetic Resonance DuaI-Modality Imaging

Multimodal imaging techniques have been demonstrated to be greatly advantageous in achieving accurate diagnosis and gained increasing attention in recent decades. Herein, we present a new strategy to integrate the complementary modalities of I9F magnetic resonance imaging （19F MRI） and fluorescence imaging （FI） into a polymer nanoprobe composed of hydrophobic fluorescent organic core and hydrophilic fluorinated polymer shell. The alkyne-terminated fluorinated copolymer （Pn） of 2,2,2-trifluoroethyl acrylate （TFEA） and poly（ethylene glycol） methyl ether acrylate （PEGA） was first prepared vie atom transfer radical polymerization （ATRP）. The PEGA plays an important role in both improving ^19F signal and modulating the hydrophilicity of Pn. The alkynyl tail in Pn is readily conjugated with azide modified tetra-phenylethylene （TPE） through click chemistry to form azo polymer （TPE-azo-Pn）. The core-shell nanoprobes （TPE-P3N） with an average particle size of 57.2±8.8 nm are obtained via self-assembly with ultrasonication in aqueous solution. These nanoprobes demonstrate high water stability, good biocompatibility, strong fluorescence and good ^19F MRI performance, which present great potentials for simultaneous fluorescence imaging and ^19F-MR imaging.

一种新型高灵敏氟-19磁共振成像分子的全合成

以儿茶酚为起始底物,通过七步反应高效简便地合成了含有72个氟原子的化合物9,化合物9以四苯并24-冠-8为母核,高度对称且具有单一的、强的氟信号,这为该分子在低浓度下的氟-19磁共振成像(fluorine-19 magnetic resonance imaging,^(19)F MRI)提供了条件。该项工作提高了各步反应的产率,优化了反应步骤,大大缩短了反应时间,得到的终产物化合物9不仅具有结构上的新颖性,同时在氟-19磁共振成像方面具有非常好的应用前景。