Evo sem

The morphology of both GS and CS Fe_xO_y-NPs, as well as their diameter distribution average, were measured by SEM with a Zeiss EVO SEM (Pleasanton, CA, USA) at 10 kV, recording images at different magnifications. The images were analyzed with ImageJ software (1.53q; National Institutes of Health, Bethesda, Maryland, USA) (free software) [54 (link)].

Surface morphology of the working electrode of SPCE before and after fabrication was observed using a ZEISS EVO SEM (Germany) with SmartSEM software for visualization and image capture. The change in contact angle of the buffer drop on the working electrode to confirm each modification step during fabrication was recorded using a Rame‐Hart 290‐F4 goniometer (USA). DPV current changes were detected using PalmsSens4 potentiostat using PSTrace v5 desktop software and final serum samples were tested on a portable electrochemical Sensit Smart device using a smartphone PStouch v2.7 software (PalmSens, Netherlands). All experimentation was conducted at room temperature and repeated thrice unless stated otherwise. All biosafety and animal‐related protocols and procedures employed, carried out at National Institute of Animal Biotechnology (DBT‐NIAB), Hyderabad were reviewed and approved by the Institutional Biosafety Committee (IBSC) with approval number #IBSC/2019/NIAB/Sonu002 and Institutional Animal Ethics Committee (IAEC) with approval number IAEC/2019/NIAB/26/SG. The institutional and national guide for the care and use of laboratory animals was followed.

Samples were fixed with 0.1 M sodium cacodylate (Sigma), 2% gluteraldehyde (Electron Microscopy Sciences), 3% paraformaldehyde (Electron Microscopy Sciences), 5% sucrose buffer (Sigma) and 1% osmium tetroxide (pH 7.4) (Electron Microscopy Sciences). The samples were then dried in increasing concentrations of high-grade ethanol, followed by critical point drying using Autosamdri 815 critical point dryer and sputter coated using Cressington 208HR sputter coater with Au or Pt/Pd. Imaging was done on a Jeol 5600LV SEM, Zeiss EVO SEM, or Zeiss FESEM Ultra55 microscope.

Raman spectroscopy and Fourier-transform infrared (FT-IR) spectroscopy were performed on Thermo Scientific-Nicolet 6700 Raman Spectroscope and iS50 FT-IR (Bangalore, India), respectively. Surface morphology was visualized via scanning electron microscopy (SEM), and elemental composition was analyzed via energy dispersive X-ray (EDX) on ZEISS EVO SEM coupled with SmartSEM software (Germany). Cyclic and differential pulse voltametric experiments were carried out on PalmSens4 potentiostat from PalmSens (The Netherlands).

Samples were fixed with 0.1 M sodium cacodylate (Sigma), 2% gluteraldehyde (Electron Microscopy Sciences), 3% PFA (Electron Microscopy Sciences), 5% sucrose buffer (Sigma) and 1% osmium tetroxide (pH 7.4) (Electron Microscopy Sciences). The samples were then dried in increasing concentrations of high-grade ethanol, followed by critical point drying using Autosamdri 815 critical point dryer and sputter coated using Cressington 208HR sputter coating with Au or Pt/Pd. Imaging was done on a Jeol 5600LV SEM, Zeiss EVO SEM or Zeiss FESEM Ultra55 microscope. For each image the total number of cancer cells, cancer cells with nanotubes, cancer cells without nanotubes, total number of nanotubes, total number of EPI–EPI membrane nanobridges, EPI–ENDO nanobridges, number of cells forming EPI–EPI nanobridges, EPI–ENDO nanobridges and number of cells positive for both EPI–EPI and EPI–ENDO nanobridges were counted. Length and width of the nanobridges were measured using the CarlZeiss TIF annotation editor. Width was measured at three different positions across the length of the nanobridges and the average width was calculated for the comparison of length and width of the nanobridges.