Helios 600 nanolabscanning electron microscope

For SEM experiments, cells were cultured and manipulated as described above to illustrate different conditions/surfaces. Cells were then fixed with 2% PFA, 2.5% glutaraldehyde in PBS for 1 h at room temperature. Fixed samples were dehydrated by exposure to a graded series of water-ethanol mixtures. Once in 100% ethanol, samples were dried at the critical point of CO₂ using a critical point drying technique (Tousimis Samdri-795) to preserve structural details. Dried samples were then coated with 10 nm of gold palladium alloy using a sputter coater (Cressington 108 Auto), and imaged using a FEI Helios 600 NanolabScanning Electron Microscope working at an accelerating voltage of 5 kV.

Surfaces were prepared as described above using a biotin-modified peptide, peptide_Ibiotin. Surfaces were incubated with gold nanoparticles modified with streptavidin (20 nm diameter, 0.5nM, Sigma) for 10 min. Excess nanoparticles were washed 3 times for 5 minutes with 1x PBS. Samples were dried and then coated with 3 nm of gold palladium alloy using a sputter coater (Cressington 108 Auto). Samples were then imaged using a FEI Helios 600 Nanolab Scanning Electron Microscope working at an accelerating voltage of 5 kV.