University of Illinois at Chicago, Department of Bioengineering, Chicago, IL 60607, USA.
Nanoscale. 2019 Jan 3;11(2):698-705. doi: 10.1039/c8nr08647h.
Understanding the biomineralization pathways in living biological species is a grand challenge owing to the difficulties in monitoring the mineralization process at sub-nanometer scales. Here, we monitored the nucleation and growth of magnetosome nanoparticles in bacteria and in real time using a transmission electron microscope (TEM). To enable biomineralization within the bacteria, we subcultured magnetotactic bacteria grown in iron-depleted medium and then mixed them with iron-rich medium within graphene liquid cells (GLCs) right before imaging the bacteria under the microscope. Using in situ electron energy loss spectroscopy (EELS), the oxidation state of iron in the biomineralized magnetosome was analysed to be magnetite with trace amount of hematite. The increase of mass density of biomineralized magnetosomes as a function of incubation time indicated that the bacteria maintained their functionality during the in situ TEM imaging. Our results underpin that GLCs enables a new platform to observe biomineralization events in living biological species at unprecedented spatial resolution. Understanding the biomineralization processes in living organisms facilitates the design of biomimetic materials, and will enable a paradigm shift in understanding the evolution of biological species.
了解活的生物物种中的生物矿化途径是一项艰巨的挑战，因为难以在亚纳米尺度监测矿化过程。在这里，我们使用透射电子显微镜（TEM）实时监测了细菌中磁小体纳米颗粒的成核和生长。为了使细菌内发生生物矿化，我们在铁耗尽培养基中培养的趋磁细菌进行亚培养，然后在将其在显微镜下成像之前，在石墨烯液相池（GLC）中将其与富含铁的培养基混合。使用原位电子能量损失光谱（EELS），分析了生物矿化磁小体中铁的氧化态，结果为磁铁矿，有少量赤铁矿。随着孵育时间的增加，生物矿化磁小体的质量密度增加，表明细菌在原位 TEM 成像过程中保持其功能。我们的结果表明，GLCs 为在前所未有的空间分辨率下观察活的生物物种中的生物矿化事件提供了一个新平台。了解生物体中的生物矿化过程有助于设计仿生材料，并将使人们对生物物种的进化有一个范式转变的理解。
