Mao Xinpei, Xu Jiadi, Cui Honggang
Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA.
Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD, USA.
Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2016 Nov;8(6):814-841. doi: 10.1002/wnan.1400. Epub 2016 Apr 4.
Nanoparticle-based magnetic resonance imaging (MRI) contrast agents have received much attention over the past decade. By virtue of a high payload of magnetic moieties, enhanced accumulation at disease sites, and a large surface area for additional modification with targeting ligands, nanoparticle-based contrast agents offer promising new platforms to further enhance the high resolution and sensitivity of MRI for various biomedical applications. T * superparamagnetic iron oxide nanoparticles (SPIONs) first demonstrated superior improvement on MRI sensitivity. The prevailing SPION attracted growing interest in the development of refined nanoscale versions of MRI contrast agents. Afterwards, T -based contrast agents were developed, and became the most studied subject in MRI due to the positive contrast they provide that avoids the susceptibility associated with MRI signal reduction. Recently, chemical exchange saturation transfer (CEST) contrast agents have emerged and rapidly gained popularity. The unique aspect of CEST contrast agents is that their contrast can be selectively turned 'on' and 'off' by radiofrequency saturation. Their performance can be further enhanced by incorporating a large number of exchangeable protons into well-defined nanostructures. Besides activatable CEST contrast agents, there is growing interest in developing nanoparticle-based activatable MRI contrast agents responsive to stimuli (pH, enzyme, etc.), which improves sensitivity and specificity. In this review, we summarize the recent development of various types of nanoparticle-based MRI contrast agents, and have focused our discussions on the key advantages of introducing nanoparticles in MRI. WIREs Nanomed Nanobiotechnol 2016, 8:814-841. doi: 10.1002/wnan.1400 For further resources related to this article, please visit the WIREs website.
在过去十年中，基于纳米颗粒的磁共振成像（MRI）造影剂备受关注。基于纳米颗粒的造影剂凭借高负载的磁性部分、在疾病部位的增强积累以及用于靶向配体额外修饰的大表面积，为进一步提高MRI在各种生物医学应用中的高分辨率和灵敏度提供了有前景的新平台。T2* 超顺磁性氧化铁纳米颗粒（SPIONs）首先在MRI灵敏度方面展现出卓越的提升。这种主流的SPION引发了人们对开发更精细的纳米级MRI造影剂版本的浓厚兴趣。之后，基于T1的造影剂得以开发，并因其提供的阳性对比而避免了与MRI信号降低相关的磁化率问题，成为MRI领域研究最多的主题。近来，化学交换饱和转移（CEST）造影剂出现并迅速受到欢迎。CEST造影剂的独特之处在于其对比可通过射频饱和被选择性地“开启”和“关闭”。通过将大量可交换质子纳入定义明确的纳米结构中，其性能可进一步增强。除了可激活的CEST造影剂外，人们对开发基于纳米颗粒的、对刺激（pH、酶等）有响应的可激活MRI造影剂的兴趣也在不断增加，这提高了灵敏度和特异性。在本综述中，我们总结了各类基于纳米颗粒的MRI造影剂的最新进展，并重点讨论了在MRI中引入纳米颗粒的关键优势。WIREs Nanomed Nanobiotechnol 2016, 8:814 - 841. doi: 10.1002/wnan.1400 有关本文的更多资源，请访问WIREs网站。
