5 Electron Probe Microanalysis of Cryosections from Cell Suspensions

摘要: Publisher Summary Single cells in suspension, such as bacteria or other microorganisms, are the specimens of choice for cryofixation. Ultra-thin cryosections prepared from these specimens, cryotransferred to a scanning transmission electron microscope, and, after freeze-drying they examined by energy-dispersive X-ray microanalysis. This method allows measurement all elements with an atomic number, Z , higher than 12 detection limit 10 mmol (kg dry weight) −1 . For magnesium and sodium, limits 20 30 respectively. The lateral analytical resolution is less 50 nm. Thus, 1000 atoms can be detected if concentrated within volume 100 nm edge width. local weight portion water determined measuring relative dark-field intensity microscopy (STEM). element concentrations converted biologically often more significant wet concentrations, per mass cell water.