Bioscope resolve system

We performed the AFM measurement with BioScope Resolve system (Bruker, Billerica, MA, USA). A silicon nitride probe with a tip radius of 70 nm was used (PFQNM-LC-A-CAL, Bruker). The operation mode is PeakForce QNM in Fluid, and the pre-calibrated spring constant is 0.075 N/m. The AFM image was measured through NanoScope Analysis software. Briefly, the keratocytes were labeled by CellTracker CMFDA and then fixed in 4% formaldehyde. We first performed epifluorescence imaging of the cell to obtain the lamellipodium structure and cell migration mode. Then we performed AFM imaging of the cell, with a resolution at 64 × 64 and a line scan rate of 0.2 Hz. After flattening the AFM image of the cell by using the plane fit tool, the height profile of the cell lamellipodium was measured by using the section tool in the analysis software.

The morphology of molybdenum foil was characterized by SEM (S4800, Hitachi, Tokyo, Japan). A three-electrode system and a CHI 760D (Shanghai, China) electrochemical workstation were used for the electrochemical experiment. Optical images were captured with an Olympus BX 53 M microscope (Tokyo, Japan). AFM from a Bruker bioscope resolve system and silicon cantilevers from nano sensors were used for intelligent mode operation. Raman spectra were recorded from a Horiba JY iHR550 (Tokyo, Japan) system with an excitation wavelength at 532 nm. During measurements, the laser beam was focused on a spot with a 1 μm diameter by a microscope objective with a magnification of 50×, and the acquisition time was set to 5 s.