*3.9. Scanning Electron Microscopy (SEM)*

The morphology of ASC and PSC was observed using a scanning electron microscope (JSM-840, JEOL, Tokyo, Japan) operated at 5 kV. The samples were pasted on a blade and sputter-coated with gold at 30 mA for 15 min. The SEM images were obtained at 50× and 400× magnification.

#### *3.10. Endotoxin Denial Test*

An endotoxin denial test was undertaken using a chromogenic end-point tachypleus amebocyte lysate (CE TAL) assay kit (Beijing Solarbio Science & Technology Co., Ltd., Beijing, China). Test samples and standards were prepared according to manufacturer's guidelines. Absorbance was measured at 405 nm using a microplate spectrophotometer (SynergyTM 2, BioTek, Winooski, VT, USA). Data were corrected to exclude background readings. A negative result was defined as a level below 0.01 EU/mL [75].
