For TEM imaging, the nanofibers were directly electrospun on carbon-coated Cu grids (200-mesh). Following laser irradiation of the nanofibers, they were visualized by a JEM 1400 plus transmission electron microscope (JEOL, Tokyo, Japan) operated at 20-60 kV. For SEM imaging, samples were first coated with 5nm platinum using a Quorum Q150T ES sputter coater. Scanning electron microscope images were taken with a Zeiss Crossbeam 540 Electron Microscope using a SE2 detector at 20 kV.
For visualization by confocal microscopy, fluorescent PCL nanofibers were fabricated by electrospinning a PCL solution mixed with the fluorophores 3-(2-benzothiazolyl)-7-(diethylamino) coumarin (coumarin-6, #12779, Sigma-Aldrich). A confocal laser scanning microscope (C1si, Nikon, Japan) with 60X water lens (Plan Apo VC, Nikon) was used to image the fluorescent PCL nanofibers. HeLa and H1299 cells grown on PEN substrates were imaged by the C1si confocal with a 10X lens (CFI Plan Apochromat, Nikon). For confocal imaging of Jurkat cells, their plasma membrane was stained with 10 μg/mL deep red fluorescent CellMask (#C10046, ThermoFisher Scientific). A series of z-stack confocal images were acquired in two channels (green channel recorded for nanofibers and deep red channel for the cells) with the 60X water lens.
For visualization by confocal microscopy, fluorescent PCL nanofibers were fabricated by electrospinning a PCL solution mixed with the fluorophores 3-(2-benzothiazolyl)-7-(diethylamino) coumarin (coumarin-6, #12779, Sigma-Aldrich). A confocal laser scanning microscope (C1si, Nikon, Japan) with 60X water lens (Plan Apo VC, Nikon) was used to image the fluorescent PCL nanofibers. HeLa and H1299 cells grown on PEN substrates were imaged by the C1si confocal with a 10X lens (CFI Plan Apochromat, Nikon). For confocal imaging of Jurkat cells, their plasma membrane was stained with 10 μg/mL deep red fluorescent CellMask (#C10046, ThermoFisher Scientific). A series of z-stack confocal images were acquired in two channels (green channel recorded for nanofibers and deep red channel for the cells) with the 60X water lens.