Charge accumulation in electron cryomicroscopy.
Charge accumulation in electron cryomicroscopy.
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DOI：
10.1016/j.ultramic.2018.01.009
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发表时间：
2018-04
期刊：
影响因子：
2.2
通讯作者：
Henderson R
中科院分区：
文献类型：
--
作者：
Russo CJ;Henderson R
提出了低剂量cryoEM中电荷积累的物理解释。我们描述了静电微透镜，是非常敏感的电荷检测器。这些微透镜允许直接测量电荷积累。在典型的显微照片的第一毫秒内，电荷积累饱和。当在透射电子显微镜照射，暴跌冻结，无定形水冰标本积累的静电荷模式，动态变化的标本被照射，这可以偏转透射电子和模糊所得的显微照片。在这里，我们提供了一个物理描述的这种电荷积累和低剂量电子低温显微镜（cryoEM）的背景下，其动态行为。我们观察到正电荷的积累，在初级照射区域从早期的工作预期。令我们惊讶的是，我们还观察到在样品附近未照射区域的负电荷积聚。使用含有纯水冰样品的标准碳支撑箔，我们在微米大小的样品孔中收集一部分负电荷，这些样品孔充当静电透镜。这些不寻常的发散微透镜是非常敏感的电荷探测器，使我们能够直接测量cryoEM成像过程中发生的电荷积累和中和的幅度和动态。使用这些测量，我们发现，建立的试样上的电荷饱和到一个动态平衡的电子注量，这是一个典型的低剂量显微照片所需的数量级以下。这里的测量将指导生物标本的最佳成像条件的发展，并有助于在电子低温显微镜信息损失的完整理论。
A physical account of charge accumulation in low-dose cryoEM is presented. We describe electrostatic micro-lenses that are extremely sensitive charge detectors. These micro-lenses allow the direct measurement of charge accumulation. Charge build-up saturates within the first millisecond of a typical micrograph. When irradiated in a transmission electron microscope, plunge-frozen, amorphous water ice specimens accumulate a pattern of static charge that changes dynamically as the specimen is irradiated, and which can deflect the transmitted electrons and blur the resultant micrographs. Here we provide a physical description of this charge accumulation and characterise its dynamic behaviour in the context of low-dose electron cryomicroscopy (cryoEM). We observe the accumulation of positive charge in the primary irradiation area as expected from earlier work. To our surprise, we also observed a build-up of negative charge in nearby unirradiated regions of the specimen. Using a standard carbon support foil containing a pure water ice specimen, we collect a portion of this negative charge in the micrometer sized specimen holes which act as electrostatic lenses. These unusual, diverging micro-lenses are extremely sensitive charge detectors that allow us to directly measure the magnitude and dynamics of charge accumulation and neutralisation that occur during cryoEM imaging. Using these measurements, we find that the build-up of charge on the specimen saturates to a dynamic equilibrium at an electron fluence which is orders of magnitude lower than required for a typical low-dose micrograph. The measurements here will guide the development of optimal imaging conditions for biological specimens and contribute to a complete theory of information loss in electron cryomicroscopy.
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影响因子：
2.2
作者：
Berriman, John A.;Rosenthal, Peter B.
通讯作者：
Rosenthal, Peter B.
影响因子：
2.8
作者：
Glaeser, RM;Downing, KH
通讯作者：
Downing, KH
影响因子：
3.2
作者：
CAZAUX, J
通讯作者：
CAZAUX, J
影响因子：
2.8
作者：
Downing, KH;McCartney, MR;Glaeser, RM
通讯作者：
Glaeser, RM
影响因子：
6.1
作者：
HENDERSON, R
通讯作者：
HENDERSON, R