Fei quanta 250 scanning electron microscope

Twelve hours after culturing BM-, AD-, and L-MSCs in serum-free medium, cells and extracted EVs were fixed in 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.2) for 2 h and washed twice with cacodylate buffer. Post-fixation with OsO₄ and FeCNK solution (1:1) for 45 min was immediately performed, followed by dehydration in a graded ethanol series for 10 min at each concentration (30, 50, 70, 90, 100%, the latter three times). After critical point drying, the coverslips were analyzed and images were acquired in an FEI QUANTA 250 scanning electron microscope (FEI, Hillsboro, OR, USA). The coverslip with BM-, AD-, and L-MSCs not subjected to serum depletion stress was used as a control.

C. albicans ATCC 10231 biofilms were formed over 5-mm sections of central venous catheters (CVCs), as previously described [28 (link)], in the presence or absence of antifungal agents at concentrations corresponding to 64 × MIC (32 μg/mL AMB, 1,000 μg/mL fraction F2 or subfraction F2.4). Antifungal treatments were also performed on mature biofilms. Catheters containing biofilms were fixed in 2.5% glutaraldehyde and 4% formaldehyde, in 0.1 M cacodylate buffer, for 1 h at room temperature, and post-fixed in 1% osmium tetroxide and 1.25% potassium ferrocyanide (in 0.1 M cacodylate buffer) for 30 min. The samples were dehydrated in ethanol increasing concentrations, critical-point-dried in CO₂, coated with gold and observed in a FEI-Quanta 250 scanning electron microscope (FEI, Japan).

Hardened paste samples were crushed, and slices of 3~5 × 0.5~1.5 mm were gathered for observation. SEM observation was conducted on the FEI Quanta 250 Scanning electron microscope (FEI Co., Hillsboro, OR, USA) at a magnification of 10,000×.