Quanta 200f scanning electron microscope

For sample preparation, 50 μL of bacteria were placed onto acetone-cleaned 12 mm Micro-cover glass slides, allowing them to adhere for 30 min. The bacteria were then fixed with 2 mL of 2.5 % glutaraldehyde for an additional 30 min. The fixed samples were subsequently rinsed twice for 30 min each with 2–3 mL of 0.1 M imidazole and then with 50, 80, and 90 % ethanol solutions (2–3 mL each) for 30 min each. The samples were then washed three times with 2 mL of 100 % ethanol and critically point dried. The dried samples were stacked in a wire basket, separated by cloth, and subjected to further drying using liquid carbon dioxide for approximately 20 min in a critical point drying apparatus. Finally, the samples were mounted on stubs, sputter gold-coated for 1 min, and imaged using a FEI Quanta 200 F Scanning Electron Microscope (Hillsboro, OR, US) with an accelerating voltage of 10 KV in high vacuum mode.

For cell morphology analysis, the discs were fixed with 2.5% w/v glutaraldehyde/PBS for 48 h as described previously [8] (link). The scaffolds were then dehydrated using a series of acetone alcohol solutions (distilled water, 50%, 70%, 90%, 100%, 100%) at room temperature and then CO₂ critically point dried. The polymer disc scaffolds were then attached to aluminum stubs with double sided sticky tabs before being coated with gold using a sc500 (EMScope) sputter coater. The polymer discs were then analysed and photographed using the FEI Quanta 200F Scanning Electron Microscope.

Strains subjected to SEM were grown for 18 h in LB broth at 37 °C with shaking at 180 rpm, diluted 1:50 into EMEM with 10 mM Hepes buffer, 100 μg/mL ampicillin, and 20 mM sodium butyrate (where indicated), and incubated at 37 °C with 200 rpm shaking for 3 h. Each culture was transferred 1:50 into fresh 5 mL aliquots of the same media and incubated an additional 3 h. Samples were pelleted (Sorvall Legend X1R, TX-400 rotor) at 4696× g for 4 min, resuspended in 50 μL PBS, and spread on 12 mm glass slides. Samples were incubated 20 min before the wells were flooded with 1 mL 2.5% glutaraldehyde and allowed to fix for 30 min. The samples were then rinsed twice for 30 min each with 2–3 mL of 0.1 M imidazole, followed by, at 30 min intervals, 2–3 mL of each of 50%, 80%, and 90% ethanol. The samples were then washed 3 times with 2 mL of 100% ethanol and critical-point dried using liquid carbon dioxide for approximately 20 min (Denton Vacuum, Inc, Cherry Hill, NJ, USA). The samples were mounted on stubs and sputter gold coated for 1 min (EMS 150R ES, EM Sciences, Hatfield, PA, USA). Samples were then viewed with a FEI Quanta 200 F scanning electron microscope (Hillsboro, OR, USA) with an accelerating voltage of 10 KV in high vacuum mode.

Phase structure of the purified nanoparticles was characterized with a Bruker D2 PHASER X-ray diffractometer (XRD) using 30 kV, 10 mA and scanned from 2θ of 10 to 80, with a scanning rate of 0.02°/s. Morphological observations of the nanoparticles were performed with an FEI Quanta 200F scanning electron microscope (SEM). For transmission (TEM) and high-resolution transmission electron microscopy (HRTEM) observations, the purified bacterial nanoparticles were suspended in water. After ultrasonication, the aqueous suspensions of bacterial nanoparticles were dropped on a carbon-coated copper grid until the solvent evolved was completely dried. The copper grid was then mounted in a TEM-FEI tecnai-F20 instrument, coupled with an Oxford energy-dispersive X-ray spectrometer (EDXS) for chemical analysis. TEM micrograph images were taken and SAED (selected area electron diffraction) patterns were acquired under a 200 kV accelerating voltage. The bacterial nanoparticle surface was characterized by Fourier transform infrared spectroscopy (FTIR, Nicolet iS10 FTIR). The FTIR spectrum was obtained with a resolution of 4 cm^-1 in the 4000–400 cm^-1 region. The optical properties of the PbS nanocrystallites were measured on a Hitachi U3900 UV–Vis spectrophotometer from 150 to 800 nm, and an F-4600 FL photoluminescence spectrophotometer.

For SEM analysis, WCSM powders were mounted on aluminum stubs with double-sided carbon tape and sputter-coated with gold for 1 min (EMS 150R ES, EM Sciences, Hatfield, PA, USA) at 20 milli Amps. Samples were then viewed with a FEI Quanta 200 F Scanning Electron Microscope (Hillsboro, OR, USA) with an accelerating voltage of 10 KV in high-vacuum mode. The images of the samples were then scanned at 500× and 1000× (magnifications) for comparison of the treatment effects.
For EDS processing, the same samples utilized above were mounted on aluminum stubs with double-sided carbon tape. Elemental analysis was done with an Oxford Xmaxⁿ 80 mm² Detector (Oxford Instruments, Tubney Woods Abingdon, Oxfordshire OX13 5QX, Hillsboro, OR, USA). Spectrum acquisition and interpretation was performed with AZtec software version 3.1 (Oxford Instruments, Hillsboro, OR, USA). Spectra were acquired at 30 KV and spot size of 5 (about 8.2 μm) for each sample.