Ultrasound and hyperpolarized magnetic resonance imaging enable the visualization of biological processes in deep tissues. However, few molecular contrast agents are available to connect these modalities to specific aspects of biological function. We recently discovered that a unique class of gas‐filled protein nanostructures known as gas vesicles could serve as nanoscale molecular reporters for these modalities. However, the need to produce these nanostructures via expression in specialized cultures of cyanobacteria or haloarchaea limits their broader adoption by other laboratories and hinders genetic engineering of their properties. Here, we describe recombinant expression and purification of Bacillus megaterium gas vesicles using a common laboratory strain of Escherichia coli, and characterize the physical, acoustic, and magnetic resonance properties of these nanostructures. Recombinantly expressed gas vesicles produce ultrasound and hyperpolarized ¹²⁹Xe MRI contrast at subnanomolar concentrations, thus validating a simple platform for their production and engineering. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2927–2933, 2018

中文翻译：

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重组表达的囊泡作为超声和超极化MRI的纳米级造影剂

超声和超极化磁共振成像可以使深部组织的生物过程可视化。但是，很少有分子造影剂可用于将这些方式与生物学功能的特定方面联系起来。我们最近发现，一类独特的气体填充蛋白质纳米结构称为气体囊泡，可以作为这些模式的纳米级分子报道分子。然而，通过在蓝细菌或盐生细菌的专门培养物中表达来产生这些纳米结构的需要限制了它们被其他实验室更广泛地采用，并且阻碍了其特性的基因工程。在这里，我们描述了使用常见的实验室大肠杆菌菌株对巨大芽孢杆菌气泡进行重组表达和纯化的方法，并描述了物理，声学，这些纳米结构的磁共振特性。重组表达的气体囊泡产生超声波并超极化¹²⁹ Xe MRI在亚纳摩尔浓度下进行对比，从而验证了其生产和工程设计的简单平台。©2018美国化学工程师学会AIChE J，64：2927–2933，2018