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Item type:Publication, Access status: with files , Serial protein crystallography in an electron microscope(Nature Publishing Group, 2020-02-21); ; ; ; Serial X-ray crystallography at free-electron lasers allows to solve biomolecular structures from sub-micron-sized crystals. However, beam time at these facilities is scarce, and involved sample delivery techniques are required. On the other hand, rotation electron diffraction (MicroED) has shown great potential as an alternative means for protein nanocrystallography. Here, we present a method for serial electron diffraction of protein nanocrystals combining the benefits of both approaches. In a scanning transmission electron microscope, crystals randomly dispersed on a sample grid are automatically mapped, and a diffraction pattern at fixed orientation is recorded from each at a high acquisition rate. Dose fractionation ensures minimal radiation damage effects. We demonstrate the method by solving the structure of granulovirus occlusion bodies and lysozyme to resolutions of 1.55 Å and 1.80 Å, respectively. Our method promises to provide rapid structure determination for many classes of materials with minimal sample consumption, using readily available instrumentation.Publicationtype: Journal ArticleScopus© Citations 68 235 190 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Visualization of cellular components in a Mammalian cell with liquid-cell transmission electron microscopy(Cambridge University Press (CUP), 2017-01-31); ; ; ; We present liquid-cell transmission electron microscopy (liquid-cell TEM) imaging of fixed and non-fixed prostate cancer cells (PC3 and LNCaP) with high resolution in a custom developed silicon nitride liquid cell. Fixed PC3 cells were imaged for 90–120 min without any discernable damage. High contrast on the cellular structures was obtained even at low electron doses (~2.5 e − /nm 2 per image). The images show distinct structures of cell compartments (nuclei and nucleoli) and cell boundaries without any further sample embedding, dehydration, or staining. Furthermore, we observed dynamics of vesicles trafficking from the cell membrane in consecutive still frames in a non-fixed cell. Our findings show that liquid-cell TEM, operated at low electron dose, is an excellent tool to investigate dynamic events in non-fixed cells with enough spatial resolution (few nm) and natural amplitude contrast to follow key intracellular processes.Publicationtype: Journal Article160 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Visualization of Multimerization and Self-Assembly of DNA-Functionalized Gold Nanoparticles Using In-Liquid Transmission Electron Microscopy(2015-11-19); ; ; ; Base-pairing stability in DNA-gold nanoparticle (DNA-AuNP) multimers along with their dynamics under different electron beam intensities was investigated with in-liquid transmission electron microscopy (in-liquid TEM). Multimer formation was triggered by hybridization of DNA oligonucleotides to another DNA strand (Hyb-DNA) related to the concept of DNA origami. We analyzed the degree of multimer formation for a number of samples and a series of control samples to determine the specificity of the multimerization during the TEM imaging. DNA-AuNPs with Hyb-DNA showed an interactive motion and assembly into 1D structures once the electron beam intensity exceeds a threshold value. This behavior was in contrast with control studies with noncomplementary DNA linkers where statistically significantly reduced multimerization was observed and for suspensions of citrate-stabilized AuNPs without DNA, where we did not observe any significant motion or aggregation. These findings indicate that DNA base-pairing interactions are the driving force for multimerization and suggest a high stability of the DNA base pairing even under electron exposure.Publicationtype: Journal Article235