SEM image of gelatin-alginate hydrogels crosslinked by diepoxy polyethylene glycol (PEG DE 500). Data underlying the research project "Gelatin-alginate hydrogels for hard-to-heal wounds" (GAlHyd)

Scanning electron microscopy (SEM). Hydrogel samples were placed in 2 ml Eppendorf microtubes, frozen in liquid nitrogen (T = -195.75 °С)for 15 min, then transferred to a pear-shaped flask, which was connected to freeze dryer Liofilizator Alpha 1-2 LD plus (CHRICT, Munich, Germany) equipped with a two-stage oil pump RZ 2.5 (VACUUMBRAND), pressure 0.1 mbar (10 Pa), temperature -55 °С. The dried samples were gold-covered in a nitrogen atmosphere (Pump/Gold JEOL JFC-1300), photographs of the morphology were taken on a scanning microscope (JEOL, JSM 6510 LV).

扫描电子显微镜（SEM）实验流程：将水凝胶样品置于2 mL 艾本德（Eppendorf）微量离心管中，于液氮（温度-195.75℃）中冷冻15分钟；随后转移至梨形烧瓶中，该烧瓶连接至德国慕尼黑CHRICT公司生产的Liofilizator Alpha 1-2 LD plus型冷冻干燥机，该设备配备VACUUMBRAND品牌的RZ 2.5型两级油泵，冷冻干燥工艺参数为压力0.1 mbar（即10 Pa）、温度-55℃。干燥后的样品在氮气气氛中采用JEOL JFC-1300型喷金仪（Pump/Gold）进行喷金处理，随后使用JEOL JSM 6510 LV型扫描电子显微镜拍摄样品形貌照片。