Mfp 3d origin atomic force microscope

Samples were prepared by applying 100 μg/mL, 20 mg/mL, 200 mg/mL, and 300 mg/mL PEG 20k solutions to freshly cleaved pieces of highly oriented pyrolytic graphite (HOPG) as to cover the whole surface of the HOPG. Samples on HOPG were incubated for 30 min. After 30 min, excess PEG 20k solution was removed from the HOPG substrate with a dry Kimwipe by capillary action. The sample was then dried in vacuo for 30 min and scanned using the MFP-3D Origin atomic force microscope from Asylum Research. Scans were conducted in a 5 μm area using the uniqprobe qp-BioAC probe and a force constant of 0.15–0.55 N/m. The scan rate was maintained at 0.4 Hz, and the scans were done with 512 scan points and lines. All samples were run in duplicate.

A powder X-ray diffractometer (XRD) was used to obtain the XRD data using a Bruker D8 Advance (Bruker AXS, Germany) with Cu/Ka radiation (λ = 1.5406 Å) at a current of 15.0 mA, a voltage of 40.0 kV, a scanning speed of 1°/min, and a step scan of 0.02°/step. Scanning electron microscopy (SEM) (FEI Quanta 650 FEG SEM) was used to study the morphology of the casted membranes and EDS mapping analysis of the prepared membranes was conducted at a voltage of 15 kV. A UV–vis spectrophotometer (Jasco V-670 absorption spectrophotometer at a scan speed of 100 nm ${ \min }^{-1}$ ) was used to measure the amount of methyl green (MG) and bovine serum albumin (BSA) in the feed and permeate solutions. Water contact angles were measured using a Rame-Hart contact angle goniometer equipped with a video camera and an image analysis system. The BET surface area and porosity were measured using an ASAP 2420 instrument with nitrogen adsorption and the measurements were calculated based on relative pressure. The surface topologies of the fabricated membrane were described with regards to surface roughness/morphology using an Asylum Research MFP-3D Origin+ atomic force microscope (AFM). The water uptake (WU) of the membranes was determined based on the dry weight of the membrane (under vacuum) and the weight of the membrane after being immersed for 24 h in DI water.

The cell morphology of MRAB 0227 was further observed by using atomic force microscopy (AFM). Briefly, mid-log phase bacterial cultures (1 × 10⁵ CFU/mL) were treated with 0.5 × MIC and 2 × MIC of peptides at 37°C for 1 h. After washing 3 times with distilled water, bacterial cells were fixed with 2.5% glutaraldehyde (pH 7.2–7.4) for 2 h. Subsequently, 20 μL bacterial suspension was incubated on the mica for 30 min at room temperature. The alterations in the bacterial cell surface were imaged by MFP-3D Origin™ Atomic Force Microscope (Oxford Instruments, USA) in the contact operation mode with a spring constant of 0.08 N/m. Images of the topography and 3D-image were acquired simultaneously. The roughness values were measured over the entire bacterial cell surface on 200 nm × 200 nm areas. The average surface root-mean-square (RMS) roughness was calculated from ten fields of three cells estimated during two independent experiments. The data were analyzed with Asylum Research AFM (Santa Barbara, CA, USA).