Microstructure and Bioactivity Visualization of GelMA Hydrogel with S. boulardii

To detect the microstructure of GelMA hydrogel and the distribution of S. boulardii in bioactive materials, the samples were pre-cooled at −80 °C for 1 h and then freeze-dried by a freeze dryer (SCIENTZ-10N, Xinzhi, Ningbo, China) at −60 °C for 24 h. After being sprayed with conductive material by Quorum SC7620, the samples were observed using a scanning electron microscope (TescanmtraLms, Brno, Czech Republic). To improve the visualization of the pore structure, the GelMA solution was labeled with rhodamine B. After photo-crosslinking, GelMA hydrogel containing rhodamine B was soaked thoroughly. GelMA hydrogel was washed and observed using a fluorescence microscope. Likewise, the fluorescein labeling method was used to observe the activity of S. boulardii bioactive materials. S. boulardii was stained by Calcofluor White (CFW; final concentration: 10 mg/mL) for 10 min [28 (link)]. After being washed several times, S. boulardii bioactive materials were observed.