Sigma 300 vp fesem

The PO₄–P concentration in the solution was measured by Hach methods (TNT844, Hach, USA) before and after the reaction. To measure TSS, water samples were filtered through a 0.45 μm pre-weighted filter. The filter was dried in an oven at 105 °C until the weight of the filter no longer changed and the increase in filter weight representing the mass of the TSS was used to calculate the TSS concentration. The precipitate was analyzed via X-ray diffraction (XRD; Rigaku Ultimate IV, Japan) and scanning electron microscopy (SEM; Zeiss Sigma 300 VP-FESEM, USA) configured with energy dispersive X-ray spectroscopy (EDS; Bruker EDS System, USA). The peaks of the XRD spectra were compared to the Inorganic Crystal Structure Database (ICSD) for struvite confirmation using the reference card PDF #97-006-0626.

The phase of the catalyst was analyzed by powder X-Ray diffraction (XRD) using a Rigaka D/max-2500 X-ray diffractometer with a Cu Kα radiation at room temperature and the data were analyzed with Jade and Xpert Highscore Plus Software. The microstructure and morphology of the catalysts, cross sectional and surface images of the cells as well as the material composition by SEM-EDS analysis were obtained at room temperature by Zeiss Sigma 300VP-FESEM equipment. Thermogravimetric (TGA) Analysis of the materials was performed using a Q600 (TA instrument) instrument in different atmospheres. The temperature program oxidation (TPO) was carried out using a TG-Mass Spectrometry (thermostat QMS 200) instruments (TG-MS). The hydrogen-temperature program reduction (H₂-TPR) analysis was performed using a home-made temperature program setup equipped with a Hewlett Packard 5,890 Series Ⅱ gas chromatograph. The X-ray photoelectron spectra were collected on a Thermo fisher Scientific K-Alpha⁺ instrument. The C1s XPS peak was calibrated to 284.6 eV, as shown in Supplementary Figure S2.

The morphology analysis of GEVs and TEVs was carried out by AFM [17 (link)]. Briefly, samples of each PEV suspension in PBS were 50-fold diluted with Milli-Q water, and 5 µL aliquots (about 10⁷ particles) were deposited onto freshly mica nanochips (TipsNano, SPM, Tallinn, Estonia). After drying completely at room temperature, the mica surface was flooded with Milli-Q water to dissolve the salt. The remaining water was removed by drying the nanochips for a 2-h incubation at 37 °C (or 24 h at room temperature). The sample topography measurements were performed in semi-contact mode using the atomic force microscope “NT-MDT-Smena B” with an NSG03 probe (NT-MDT, Moscow, Russia).
The visualization of GEVs and TEVs was also conducted by SEM. Briefly, samples in PBS were diluted 10-fold with Milli-Q water, and 100 μL aliquots were deposited onto coverslips. Then, samples were fixed with 2.5% glutaraldehyde, washed three times with 0.05% PBS, and dehydrated progressively with 30, 50, 70, 80, 90, and 100% ethanol. Samples were subjected directly to a FESEM system (Sigma 300 VP FESEM, Carl Zeiss, Jena, Germany) for morphology visualization without coating.

Scanning electron microscopey (SEM., Zeiss Sigma 300 VP-FESEM) was used to observe the TCNF fibre diameter and the ECM formation of the bioprinted constructs after 6 weeks of in vitro culture. Each construct was fixed in sodium cacodylate trihydrate buffer containing 2% v/v glutaraldehyde and 2.5% v/v paraformaldehyde overnight. The samples were then cut in half and washed twice with deionized water to wash away the fixation solution. The samples were further treated with osmium tetroxide and tannic acid before SEM observation. All the reagents were purchased from Electron Microscopy Sciences (Pennsylvania, United States).