Sc7640

Visualisation of CPB was performed using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). For TEM, we put a few drops of the CPB solution on a carbon-coated copper grid (Structure Probe, Inc.), stained the sample with 2% uranyl acetate (Electron Microscopy Sciences), and carried out TEM (JEOL JEM-2100, Jeol). For SEM, we pipetted a few drops of the CPB solution on a glass microscope slide (Thermo Scientific), dried at room temperature (RT) O/N, mounted the slides on a double sided adhesive conductive carbon tape (Ted Pella), sputter coated with Au-Pd (SC7640, Emitech), and finally performed SEM (Zeiss CrossBeam 1540 XB, Carl Zeiss). For AFM, we pipetted a few drops of the CPB solution on a mica disc (Ted Pella), and conducted AFM using Cypher™ Atomic Force Microscope (Asylum Research).

Scanning electron microscopy (Carl Zeiss field emission gun (FEG)-SEM LEO 1530VP), which can provide images of the electrospun sample microstructures by scanning them with a focused beam of electrons, was used in the measurement of fibre–fibre distance and fibre diameter for all porous membranes/scaffolds prepared in this work. The operating principles of SEM are found elsewhere [20 (link),21 (link)] and, therefore, are not discussed in this paper. Due to the non-conductivity of the polymers, PCL samples were provided with a 2–20 nm thin coating of electrically conducting metal, namely, gold/palladium (Au/Pd) using a sputter coating machine (Emitech, SC7640). Then, the coated samples were monitored using the SEM. Both the top and cross-sectional views of the samples were taken. Fibre–fibre distance and fibre diameter were measured after setting the scale by the reference distance on the SEM images. For each image, one hundred fibres were randomly chosen for the measurements. The mean value, distribution of fibre–fibre distance and fibre diameter were then determined.