Leica sputter coater

In this study, pure alginate, G10, and G20 beads were imaged to determine differences in surface roughness and overall appearance. Hydrogel beads used for imaging were fabricated using the above technique, followed by 4 h of lyophilization. Prior to imaging, lyophilized beads were sputter-coated with 10 nm of gold–palladium using a Leica sputter coater (Leica Microsystems) and mounted on SEM stubs with double-sided SEM stickers. Images were acquired through a scanning electron microscopy (SEM, FEI Teneo, FEI Co.) setup employed at an accelerating voltage of 5.00 kV. Magnifications ranging from 400x to 600x were used for image acquisition. The porosity of samples was calculated using cross-sectional SEM images. Using ImageJ analysis, the pixel area of pores was compared to that of the entire image, and a percent porosity was calculated. Analysis was carried out on n = 4 images of different areas of the cross-section for each sample type.
The SEM setup was also equipped with an energy-dispersive X-ray spectroscopy system (EDS, Oxford Instruments) used for elemental surface mapping and analysis. Oxygen and carbon were used to confirm the alginate surface and sulfur was utilized to map the distribution of GSNO in the hydrogel beads. An accelerating voltage of 20.00 kV was used for EDS measurements.

Scanning Electron Microscopy (SEM, FEI Teneo, FEI Co.) is a technique utilizing a focused electron beam to examine surface morphology. The SEM instrument was accompanied with an Energy-Dispersive X-ray spectroscopy system (EDS, Oxford Instruments) in order to determine the concentration and dispersion of SNAP and Se nanoparticles in the samples using elemental analysis. The presence of SNAP was measured by the detection of sulfur located in the S-NO bond. An accelerating voltage of 5.00 kV and 20.00 kV was employed to examine samples with SEM and EDS, respectively. Samples were coated with 10 nm of gold-palladium using a Leica sputter coater prior to inspection (Leica Microsystems).