Cryo-Transmission Electron Microscopy

An aliquot (3 μL) of solutions containing 1₆, precursors, or both (4 mM, prepared in borate buffer) was deposited on holey carbon-coated grids (3.5/1 Quantifoil Micro Tools, Jena, Germany) that were previously glow-discharged for 15 s. After the excess liquid was blotted for 4 s, the grids were vitrified in liquid ethane using a Vitrobot (FEI, Eindhoven, The Netherlands) and transferred to a FEI Tecnai T20 electron microscope equipped with a Gatan model 626 cryo-stage operating at 200 keV. Micrographs were recorded under low-dose conditions with a slow-scan CCD camera.