Multimode scanning probe microscope

The assembled structures were deposited on freshly cleaned muscovite mica (Electron Microscopy Sciences) for five minutes, then rinsed with MQ-pure water and dried under nitrogen gas. AFM imaging was performed in air in ScanAsyst mode on a Veeco Multimode Scanning Probe Microscope with silicon Scanasyst-air probes (resonant frequency 50–90 kHz, spring constant 0.4 N m⁻¹, and a tip radius of 2 nm).
For TEM imaging, a JEM 2010 transmission electron microscope (JEOL) operated at 200 kV was used. The images were analyzed using a GATAN MSC 794 CCD Camera and GATAN Digital Microscopy software. Five μL AuNP assemblies were transferred to SPI® Supplies Holey carbon coated grids onto 400 mesh copper, incubated for three minutes, washed with 50 μL of MQ-pure water, and dried under nitrogen gas. Samples were then dried completely for at least 15 hours under ambient conditions in a vacuum desiccator.

Field-emission gun scanning electron microscopy (FEG-SEM) was used to image the dispersion of the rGO by examination of fractured samples of the nanocomposites. A Leo 1525 (Carl Zeiss, Germany) microscope was used, with an accelerating voltage of 5 kV. The samples were sputter-coated with a thin film of chromium prior to examination. Transmission electron microscopy (TEM) was carried out using a 2000FX microscope (JEOL, USA) employing an accelerating voltage of 200 kV. Thin slices (about 70 nm in thickness) were cut for TEM using a PowerTome XL ultramicrotome (RMC Products, UK). Atomic force microscopy (AFM) was carried out to determine the morphology of the GO using a MultiMode scanning probe microscope (Veeco, UK). The microscope was equipped with a NanoScope IV controller and an E scanner. The concentrated aqueous GO suspension (13 mg/mL) was diluted to 0.1 mg/mL using deionized water. The diluted GO suspension was then dip-coated onto a mica sheet (Agar Scientific, UK) and allowed to dry. Height and phase images were captured by AFM at a resolution of 512 pixels × 512 pixels and a scan speed of 1 Hz, using silicon probes in a tapping mode of operation.

For Atomic force microscopy (AFM) measurements, scr-MDA (control) and sh-MDA (GPAT2 silenced) cells were plated on glass coverslips and grown in routine medium without the addition of AA for 1−2 days until 80% confluent. Then, the cells were fixed using an ethanol dehydration train at room temperature and subsequently air dried [18 (link)]. Fixation is necessary because high-resolution images of cells are poorly achieved in solution, and the enhanced AFM resolution obtained with fixed cells allows a more detailed subcellular analysis [12 (link)].
AFM images were obtained in air, using a MultiMode Scanning Probe Microscope (Veeco) equipped with a Nanoscope V controller (Veeco). All measurements were obtained immediately after fixation with Tapping^® mode, using probes doped with silicon nitride (RTESP, Veeco with tip nominal radius of 8–12 nm, 271–311 kHz, force constant 20–80 N/m). Typical scan rates were 0.5 Hz.
The analysis was first performed on a large area (50 μm²) with a single cell, and later by heading the cantilever to the cell surface to obtain images of 30 μm², 15 μm², and 10 μm². The same procedure was repeated in six different cells (three cells each time in two independent AFM measurements), with three different AFM acquisition modes: height, phase, and amplitude.

The AFM images (5 µm × 5 µm) were obtained with a Veeco Multimode scanning probe microscope equipped with a Nanoscope IV (Veeco Instruments, Santa Barbara, CA, USA), a controller operating in tapping mode with a phosphorus doped silicon cantilever (model RTESP). Mean square roughness values were extracted from these images. The surface images were obtained by scanning electron microscopy (SEM) using a Hitachi SU-8000 instrument (Hitachi, Ltd., Tokyo, Japan). Raman spectra were obtained with a Micro-Raman Spectrometer (LabRAM HR Evolution; Horiba, Kyoto, Japan). Surfaces were excited at 785 nm. Optical characterization: both ellipsometric and reflectometric measurements were taken with a GES 5E (SOPRA Company, Courbevoie, France), provided with a variable angle goniometer, Xe-lamp, monochromator and photomultiplier. The reflectance diffuse spectrum was characterized in a Jasco 616 spectrophotometer (Jasco Co., Tokyo, Japan).