Xe 100 afm

The surface morphology and roughness of the membranes were analysed using an AFM XE-100 (Park Systems, USA). The measurements were taken at ambient conditions and the membranes were dried at room temperature prior to analysis. Membrane samples were cut into approximately 1 cm² sizes and each sample was secured on the top of a scanner tube with carbon tape, followed by scanning with the laser beam reflected by the cantilever, within a scanning area of 10 µm × 10 µm. Generally, three measurements are conventionally used to define roughness: the mean roughness (R_a), the root mean square roughness (R_q), and the average difference in the heights between the highest and the lowest points (R_z). In this study, R_q was used as the evaluation measurement to compare the roughness of the membranes produced and was the defined roughness parameter studied using the AFM XE Data Acquisition program in non-contact mode. Mathematically, R_q is defined as the average value of the surface relative to the central plane for which the volumes enclosed by the images above and below the plane were equal, as represented in Equation (1): $R_q={\left[\frac{1}{S}{\displaystyle \underset{0}{\overset{a}{\int }}{\displaystyle \underset{0}{\overset{b}{\int }}{\left\{f(x,y)-z_m\right\}}^2}}dxdy\right]}^{\frac{1}{2}}$
where f(x,y) is the height in the specified area, S is the specified area, a and b are the length of the sample, and Z_m is the mean height value.

In the cell-cell coculture model, 12 h and 24 h coculture and monococulture samples were collected and observed under Axioskop 40 pol optical microscope (Zeiss). The samples were collected from 3 biological replicates and at least 20 images were taken for each sample. For the determination of cell surface roughness, the samples were firstly scraped with a sterile blade to expose the substrate. Afterwards, the probe was used to approach and make contact with the cells and the substrate using AFM XE-100 (Park Systems). AFM performed in non-contact mode was used to characterize the morphology of individual cells in air (38 (link)). Silicon cantilever (PPP-NCHR, Nanosensors) with spring constant of 42 N/m and resonance frequency of 330 kHz was used. The scan rate was 0.5 Hz and the image resolution was 256 pixels × 256 pixels. Data were recorded for at least 10 fields of view per sample and results represent typical observation in each field. Surface roughness was determined using XEI software.

In the cell-cell coculture model, 12 h and 24 h coculture and monococulture samples were collected and observed under Axioskop 40 pol optical microscope (Zeiss). The samples were collected from 3 biological replicates and at least 20 images were taken for each sample. For the determination of cell surface roughness, the samples were firstly scraped with a sterile blade to expose the substrate. Afterwards, the probe was used to approach and make contact with the cells and the substrate using AFM XE-100 (Park Systems). AFM performed in non-contact mode was used to characterize the morphology of individual cells in air (38 (link)). Silicon cantilever (PPP-NCHR, Nanosensors) with spring constant of 42 N/m and resonance frequency of 330 kHz was used. The scan rate was 0.5 Hz and the image resolution was 256 pixels × 256 pixels. Data were recorded for at least 10 fields of view per sample and results represent typical observation in each field. Surface roughness was determined using XEI software.