4.6. Cell-Material Interaction

We examine the cell morphology, the spreading patterns, and cell-material interaction of hFOB 1.19 cells cultured onto the PLA fiber scaffold and PLA/ZrO₂ of 0.5 g nanocomposite fiber scaffold, because it demonstrated the best results for adhesion and viability. Briefly, hFOB 1.19 cells were cultured at a density of 1 × 10⁴ cells/mL onto the scaffolds for 24 h in triplicate. Then, the samples were analyzed using SEM and fluorescence microscopy (AMSCOPE). For SEM analysis, after 24 h of incubation, scaffolds were washed three times with PBS, fixed with 4% formaldehyde, then dehydrated with a graded series of ethanol (25–100%) and air-dried. Next, the samples were sputter-coated with a thin layer of gold and examined by SEM. For fluorescence observation, before seeding the hFOB 1.19 cells onto the scaffolds, cells were incubated with CellTracker™ Green (CMFDA, 5-chloromethylfluorescein diacetate) in phenol red-free medium at 37 °C for 30 min. Subsequently, the cells were washed with PBS and incubated for 1 h in a complete medium. Then, hFOB 1.19 cells were trypsinized and counted to the desired cell concentration (1 × 10⁴ cells/mL), incubated for 24 h onto the scaffolds, and examined under the microscope.