Pp211

The sheet resistance of modified electrodes was measured with Fluke Ohmmeter (1550B). Absorption measurements were taken with a single beam UV–Vis Spectrophotometer (CECIL CE9200) from 200 to 800 nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) tests were done on prepared samples using (LEO 1455VP) and (Micro Photonics Inc/ Dual scope DS95-200E) instruments, respectively. A fluorescence spectrometer (PerkinElmer LS55) was used to measure the fluorescence intensity of tested samples. The cyclic voltammetry (CV) measurements were performed on electrodes using a (Zahner PP211 potentiostat) in the three-electrode electrochemical cell. In this test, the surface of prepared electrodes was used as a working electrode, and platinum was used as a counter electrode with Ag/AgCl as the reference one. A KCl solution (0.1molar in deionized water) was used as a standard electrolyte in all tests. In all of CV tests, the potential scan step was 0.005 V, and the potential scanning speed was 0.05 Vs⁻¹. Each cyclic voltammogram presented in this research work is the most representative cycle obtained for each experiment.

After cell capture, the washed CNF-Chip with cells was taken out and placed in an electrolytic cell with PBS as the electrolyte. The conductive CNF-Chip was taken as the working electrode, Ag/AgCl electrode was the reference electrode, and the platinum electrode was the counter electrode. A potential of −1.2 V was then applied by the electrochemical workstation (Zahner PP211) for 6 min. The cells were then released and collected by well plates. After that, the residual cells on the CNF-Chip were fixed with 2.5% glutaraldehyde for 30 min, stained with DAPI for 20 min, and observed under a fluorescence microscope. Five random fields of the sample were photographed. The obtained images were analyzed by ImageJ software, and the release efficiency ( ${\mathrm{E}}_{\mathrm{R}}$ ) was calculated according to Equation (3): $${\mathrm{E}}_{\mathrm{R}}\left(\%\right)=(1-\frac{{\mathrm{N}}_{\mathrm{R}}}{{\mathrm{N}}_{\mathrm{T}}{\times \mathrm{E}}_{\mathrm{C}}})\times 100\%$$
where ${ \mathrm{N}}_{\mathrm{R}}$ is the number of residual cells on the CNF-Chip after release, ${\mathrm{N}}_{\mathrm{T}}$ is the total number of cells pumped in, and ${\mathrm{E}}_{\mathrm{C}}$ is the capture efficiency.

The scanning electron microscope (SEM) images were obtained by the field emission SEM (ZEISS, Germany). Photoelectrochemical (PEC) measurements were performed on an electrochemical workstation (Zahner Zennium PP211, Germany).