Vacuum desk 4

Scanning electron microscopy (SEM) imaging was used to examining the morphologies of E. coli cells retained on MWCNTs filters, MWCNTs–CDots filters, and MWCNTs–SWCNTs filters. All the tested filters had 3 mg MWCNTs loadings with or without 0.15 mg CDots or SWCNTs coating on the surface. The captured cells on each filter were first sat at room temperature for 1 h, then fixed overnight by immersing into 1 mL of 4% formaldehyde and 2% glutaraldehyde solution in a 1.5 mL centrifuge tube at 4 °C. The fixative was removed and the filters were gently rinsed with 1 mL DI-H₂O. The filters were then air dried and coated with gold using Denton Vacuum Desk IV (Czech Republic). The FEI XL30 microscope (Netherlands) was used to take SEM images at the Shared Materials and Instrumentation Facility (SMIF) in Duke University.

A JEOL JSM 6490LV scanning electron microscope (Akishima-Tokio, Japan) was used to analyze the avocado seed starch images. Samples were fixed on a graphite tape, impregnated with a layer of gold (Au) using a DENTON VACUUM Desk IV equipment, and subsequently analyzed in a high vacuum scanning electron microscope to obtain high-resolution images (Liu et al., 2009 (link)).

Longitudinal and transversal decellularized tissue samples were examined by SEM. The longest side of the commercial sample was labeled as longitudinal, while the PEM sample in the cephalocaudal direction of the esophagus was considered to be longitudinal and transversal in the coronal direction.
The samples were fixed with 10% buffered formaldehyde (Merck, Darmstadt, Germany) for 24 h, after which the formaldehyde was removed and 2.5% glutaraldehyde (Merck) was added, left in this solution for 2 h, and dehydrated by a successive series of 30%, 50%, 70%, 90%, 95%, and 99% ethanol. The samples were critical-point dried (Sandri PVT 3D Tousimis, Rockville, MD, USA) at 31 °C and 1072 PSI, fixed on graphite tape, and sputtered with gold (Denton Vacuum Desk IV, Moorestown, NJ, USA.). The samples were evaluated in a scanning electron microscope (Jeol JSM 6490 LV, Peabody, MA, USA) under vacuum to obtain high-resolution images. A secondary electron detector was used to evaluate the samples’ morphology and topography.

Fresh grown E.coli cells were washed three times and resuspended in PBS solution. The cells were then treated with 8.82 mM H₂O₂ and 10 μg/mL CDots alone or in combination under light for 1 h, followed by overnight fixation with 4% formaldedyde and 2% glutaraldehyde solution at 4°C. After removing fixative and washing with DI-H₂O, the samples at the volume of 10 μL for each were loaded on silicon slide covers and air-dried. All the samples were then coated with gold using Denton Vacuum Desk IV (Czech Republic). SEM images were taken using the FEI XL30 microscope (Netherlands) at the Shared Materials and Instrumentation Facility (SMIF) at Duke University.

Scanning electron microscopy (SEM) inspection was performed in a JSM-6490LV^® microscope (JEOL USA Inc., Peabody, MA, USA) with a 10 kV accelerating voltage. Before the examination, samples were cryofractured on liquid nitrogen with perpendicular and parallel cuts with respect to their length, fixed onto aluminum plates with carbon tape, and coated with a thin layer of gold using Vacuum Desk IV Denton Vacuum, Moorestown, NJ, USA) apparatus. SEM micrographs were processed with Fiji^® and ImageJ^® software packages (version 5.2.0, National Institutes of Health, Bethesda, MD, USA) to analyze the average fiber diameter, size distribution, and relative fiber alignment of electrospun mats by quantifying the diameter of 200 randomly selected fibers in three SEM images at 500× magnification. The relative fiber alignment of the electrospun layers was then analyzed with fast Fourier transform (FFT) [33 (link)] by translating optical information into the frequency domain and extracting the radial summing of the pixel intensities in oval projection discretized into 100 points aided by the oval profile plugin. The results were normalized with respect to the minimum value in the dataset and plotted in arbitrary units ranging from 0 to 0.15 [29 (link)]. Values above 0.065 units together with two larger peaks observed at 90° and 270° were interpreted as aligned fibers [34 (link)].