*2.5. Biomineralization Activity*

According to our previous report, the specimens incubated in simulated body fluid (SBF) for a certain time to determine the biomineralization activity of hybrid membranes [22]. After soaking, the formation of apatite on the surface of the sample was tested. Briefly, the samples were cut into a size of 10 × <sup>10</sup> × 2 mm3 and incubated in SBF with a similar composition to human blood plasma (in mM: Ca2+ 2.5, Mg2+ 1.5, Na<sup>+</sup> 142, K+ 5.0, SO4 2− 0.5, HPO4 <sup>2</sup><sup>−</sup> 1.0, Cl<sup>−</sup> 147.8, HCO3 − 4.2). After 7 days of incubation at 37 ◦C, the samples were taken out of the fluids and washed with deionized water to remove the specimen. Then, the samples were dried at 40 ◦C for 24 h. Then, the activity of apatite forming on the surface of the samples was analyzed by SEM, EDS, and XRD.
