Ac160ts r3

Atomic force microscopy (AFM) was used to characterize the topography of the PEMs. The AFM measurements were carried out at ambient conditions (≈40% RH) with the MFP-3D SA (Asylum Research, Oxford Instruments, Scotts Valley, CA, USA). The cantilevers used were the AC160TS-R3 with a silicon probe and a tip diameter of 7–8 nm, also from Asylum Research. To determine the roughness of the PEMs, images of 25 µm² were taken at three different positions of the sample, and the roughness was determined from nine randomly selected 1 µm² areas of the image. The roughness is defined as the root mean square (RMS) of height deviations of the surface mean plane. The depicted error bars correspond to the standard deviation of the 27 spots measured. For PEMs with surface patterns with a correlation length in the µm range, the roughness was determined on the whole 25 µm² area. In all cases, the two different roughness measurements (1 µm², 25 µm²) led to similar values.

Atomic force microscopy (MFP-3D AFM, Asylum Research, Goleta, CA, USA) was performed on electric field-treated and untreated samples to observe the alignment of bacteriophages. Areas of 50 µm² were scanned at 0.10 Hz with standard silicon cantilevers (AC160TS R3, Asylum Research, Goleta, CA, USA) using the tapping mode with a tip spring constant of 26 N/m and resonance frequency of 305 kHz. Images were exported and edited using Igor Pro 6.3.7.2 (Asylum Research, Goleta, CA, USA).

AFM analysis was conducted with an MFP3D Infinity-Asylum Research AFM in tapping mode (Oxford Instruments PLC, Oxfordshire, UK). Briefly, cells were seeded onto the 10 mm glass coverslip and cultured in a 6-well culture plate for 24 h. Subsequently, cells were inoculated with PDCoV (MOI = 10) and incubated at 4 °C for 1 h. After washing, cells were fixed with 4% formaldehyde in PBS. Imaging was performed with uncoated silicon cantilevers AC160TS-R3 from Oxford Instruments PLC, with a tip radius of 7 nm, resonance frequency of approximately 200–300 kHz, and a spring constant of 8.4–57 k (N/m). Images with a scan size of 1 × 1 μm2/4.5 × 4.5 μm²/20 × 20 μm² and resolution 512 × 512 pixels² were obtained with scan rates between 0.6 and 1.0 Hz and set points close to 0.2 V. AFM images were analyzed offline in AFM software (Ergo; Oxford Instruments PLC, Oxfordshire, UK).