Xl30 esem feg environmental scanning electron microscope

Hydrodynamic size, polydispersity index (PDI) and the zeta potential of TAC-NMF and placebo NMF were determined by Dynamic Light Scattering (DLS) Zetasizer Nano ZS, Malvern Zetasizer, Westborough, MA, USA. For this, 700 µL of TAC-NMF or placebo NMF were placed in a glass cuvette in the DLS instrument (Malvern Zetasizer, Westborough, MA, USA). Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) was used to access the morphology of TAC-NMF. TAC-NMF in solution state was analyzed by TEM while lyophilized TAC-NMF was analyzed by SEM. Philips CM12 Scanning Transmission Electron Microscope was employed for SEM imaging and Philips XL30 ESEM-FEG Environmental Scanning Electron Microscope instrument was used for SEM imaging. TEM analysis of TAC-NMF was performed by placing 50 μL of TAC-NMF on a carbon-coated copper grid. Followed by negatively staining the sample by phosphotungstic acid. For SEM imaging, For the SEM analysis, lyophilized TAC-NMF was treated as a non-conductive wet sample and imagining was taken in the “wet” mode.

Biofilms were prepared for scanning electron microscopy using a previously published protocol³⁴ (link) with modifications. Single- and dual-species biofilms were grown on cell culture-treated plastic coverslips (Thermo Fisher Scientific) in 24-well plates for 24 h, after which the MHB medium was replaced with MHB with or without 5 mg/L meropenem. At 48 h, coverslips were washed twice with PBS and samples fixed in 2.5% glutaraldehyde in 0.1 M phosphate buffer for 1 h, at 4°C. Samples were dehydrated using increasing ethanol concentrations (50%, 70%, 90% and 100%) twice for 15 min each. Ethanol was replaced with liquid CO₂ and heated up to the critical point to dry the samples. Each coverslip was mounted on a stub and sputter-coated with platinum. Scanning electron microscopy images were captured using a Philips XL30 ESEM-FEG environmental scanning electron microscope.

The concentrations of the Ni(II) solutions were measured by inductively coupled plasma optical emission spectroscopy (The ATI Unicam 701-Emission Inductively Coupled Argon Plasma Spectrophotometer, USA) and a UV-Visible spectrophotometer (Cary 100 UV-Vis, Agilent Technologies, USA) by applying the Dimethylglyoxime method.^[28] Fourier transform infrared (FTIR) spectra of the samples were recorded with a Varian 800 FTIR spectrometer. Scanning electron microscopy (SEM) measurements were performed on a Philips XL30 ESEM FEG environmental scanning electron microscope, Netherland. A zetasizer Nano ZS (Malvern, Instruments Ltd., UK) was used for zeta potential measurements using the setting for a polystyrene standard. Size of the samples was estimated by TEM from Philips CM-100, Netherlands with tungsten filament.