Fei nova nanosem field emission scanning electron microscope

Nanocrystal shape and surface features were observed with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). For TEM, freshly prepared samples were placed on a 400 mesh formvar-coated carbon grid. Excess sample was removed using a filter paper. The grid was then negatively stained with 1% uranyl acetate, dried in air, and visualized under FEI Tecnai T20 Transmission Electron Microscope (Hillsboro, OR, USA) at an accelerated voltage of 200 kV. Samples for SEM were sputter coated with platinum for 60 sec and visualized with a FEI NOVA NanoSEM field emission scanning electron microscope (FEI Company, Hillsboro, OR, USA) at an excitation voltage of 5 kV, spot 3, 3 mm of working distance and 30 µm aperture. The size of DTX-F-alb NCs was analyzed from EM images with the ImageJ software (National Institutes of Health, Bethesda, MD, USA).

Cryo-scanning electron microscopy (cryo-SEM) images were acquired by the
Life Science Microscopy Facility (Purdue University, West Lafayette, IN).
Hydrogel samples were prepared as described above and immersed in PBS until
fully swollen. The hydrogels were then rinsed with Milli-Q water to remove
residual salts. Samples were plunged into nitrogen slush to preserve network
structure. Frozen samples were fractured to reveal the cross section of the
samples, and they were coated with platinum. SEM images were taken on an FEI
NOVA nanoSEM field emission scanning electron microscope (FEI Company,
Hillsboro, OR) using an Everhart-Thornley (ET) detector operating at an
acceleration voltage of 5 kV.
Image J (NIH, Bethesda, MD)[53 (link)]
was used to analyze pore sizes of RZ10-RGD hydrogels. Pore sizes were determined
by averaging the lengths of the major and minor axes of each pore. Data are
reported as an average of three replicates ± standard deviation, and each
replicate consisted of at least 195 pores.