@phdthesis{Blach2022,
  author    = {Blach, Patricia S.},
  title     = {Electron beam damage of biological specimens in liquid-phase electron microscopy},
  organization    = {INM - Leibniz-Institut f{\"u}r Neue Materialien},
  doi       = {10.57954/opus-531},
  institution = {Interactive Surfaces},
  school    = {Universit{\"a}t des Saarlandes},
  year      = {2022},
  abstract  = {Electron microscopy of native biological materials is usually hampered by sample preparation procedures such as dehydration and freezing, and by electron beam damage. Liquid phase electron microscopy (LP-EM) allows the observation of biological samples in liquid environments without conventional preparation procedures. However, electron beam damage also occurs in LP-EM, and thresholds for biological samples are not yet fully explored. In this work, the electron dose tolerance of green fluorescent protein (GFP) was analyzed in LP-EM. Protein damage was studied with increasing electron dose, using fluorescence degradation as an indication. Dc < 0.01 e-/{\AA}² and Dc < 0.1 e-/{\AA}² were observed for GFP on silicon nitrite in transmission electron microscopy (TEM) and environmental scanning electron microscopy (ESEM), respectively. In TEM, the dose tolerance was increased by three orders of magnitude when GFP was encapsulated in graphene liquid cells. The dose tolerance of more complex systems was investigated by binding GFP to actin filaments in fixed SKBR3 cells, which showed Dc < 0.1 e-/{\AA}² in TEM and ESEM. In fixed SKBR3 cells, radiation damage was also studied based on the displacement of labeled membrane proteins. At electron doses of D = (7.8 ± 0.4) ∙ 10³ e-/{\AA}² these labels showed a displacement of 0.8\%. Procedures for studying biological materials such as proteins and fixed cells in LP-EM are presented in this thesis. Strategies to study and mitigate beam damage are demonstrated.},
  language  = {en}
}