2.2.3. Chemico-Physical Characterization

Scaffold morphology was analyzed using scanning electron microscopy (SEM, Tescan, Mira3XMU, Brno, Czechia, CISRIC, University of Pavia, Pavia, Italy) after graphite sputtering in a vacuum. Nanofiber diameters were measured (Image J, ICY, Institute Pasteur, Paris, France). The presence of nanocomposite (VHS-Ns) loaded into the hybrid scaffolds was investigated by ultra-high-resolution transmission electron microscope (HR-TEM, FEI Titan G2 60–300, Thermo Fisher, Barcellona, Spain), coupled with analytical electron microscopy (AEM), with a SUPER-X silicon-drift windowless energy-dispersive X-ray spectroscopy detector. X-ray chemical element maps were collected. The samples were directly deposited onto copper grids (300 mesh coated by formvar/carbon film, Agar Scientific, Rome, Italy).

X-ray powder diffraction (XRPD) analysis was carried out using a diffractometer (X-Pert Pro model, Malven Panalytical, Monza, Italy) equipped with a solid-state detector (X-Celerator) and a spinning sample holder. The diffractogram patterns were recorded using random oriented mounts with CuKα radiation, operating at 45 kV and 40 mA, in the range 4◦–60◦ 2θ. The diffraction data were analyzed using the XPOWDER® software (Version 2017).

Fourier transform infrared spectroscopy (FTIR) spectra of the samples were recorded using spectrophotometer (Spectrum BX FTIR, PerkinElmer, Milan, Italy). All analyses were performed from 400 to 4000 cm−<sup>1</sup> with a resolution of 0.25 cm<sup>−</sup>1. The results were processed with a software package (Spectrum, Perkin Elmer, I). In the Supplementary Materials, the spectra of the pristine components are reported (Figure S1).
