## 3 Results  
### Pre-Test Characterization  
Figure 2 shows representative images of water contact angles as measured on the three samples. The uncoated Ti-alloy substrate was the least hydrophilic and presented a contact angle of \(71^{\circ}\pm 1^{\circ}\). The two samples coated with fibers achieved a remarkable improvement in hydrophilicity, in particular the CS/PEO with a contact angle of \(18^{\circ}\pm 3^{\circ}\), while the one functionalized with BG had a contact angle of \(34^{\circ}\pm 1^{\circ}\). In order to fully characterize the starting materials, dominant peaks of FTIR spectra of BG, CS, PEO, CS/PEO, and CS/PEO/BG (a-e) were identified as shown in Figure 3.  
Figure 3: FTIR spectra of BG (a), CS (b), PEO (c), CS/PEO (d) and CS/PEO/BG (e) nanofibers. The labels, differently colored, indicate the most represented bands of BG (green), CS (red) and PEO (black). Figure 2: Water contact angle measurements on Ti-alloy and two Ti-alloy nanofiber-coated substrates (each sample labeled with a different color). Three substrates for each class were tested. CS: chitosan; BG: bioactive glass; PEO: polyethylene oxide. The spectrum of PEO presented main bands of asymmetric and symmetric stretching of C=O at 1110 and 1146 cm\({}^{-1}\), respectively [28; 29]; and bands related to CH\({}_{2}\) asymmetric stretching (1287 cm\({}^{-1}\)), CH\({}_{2}\) symmetric twisting (1241 cm\({}^{-1}\)) and two bands related to CH\({}_{2}\) wagging (1348 and 1360 cm\({}^{-1}\)), respectively [28; 30; 31; 32]. About CS, two main ranges between 1000 and 1200 cm\({}^{-1}\) and between 1500 and 1700 cm\({}^{-1}\) are characteristic of the compounds. In the first range, mainly, there are bands of C-O stretching (1029 cm\({}^{-1}\)) and symmetric and asymmetric stretching of C-O (1066 cm\({}^{-1}\)), while the second range is characterized by vibrational modes of amide II (N-H bending at 1557 cm\({}^{-1}\)), amide I (stretching C=O and N-H bending at 1663 and 1595 cm\({}^{-1}\), respectively) [28; 30; 33; 34; 35]. About the spectrum of BG, three distinct and very broad bands can be identified at 934 cm\({}^{-1}\) (Si-O stretching), 1035 cm\({}^{-1}\) (Si-O-Si bending) and 1463 cm\({}^{-1}\) (carbonate species) [36; 37]. The two spectra related to nanofiber-coated surfaces, with and without BG, were analyzed and fitted as reported in Figure 4 and a summary of all the main bands with the indications of the assignment is provided in Table 1[28; 38; 39; 36; 38; 39; 40; 29; 36; 38; 36; 39; 40]. Bands indicated previously and referred to PEO and CS compounds are labeled. The spectrum of CS/PEO/BG, in particular, presents Band 3, located at 934 cm\({}^{-1}\) and assigned to Si-O stretching, and shows an increase in Band 6 (1029 cm\({}^{-1}\)), which derives from the contribution of BG (band related to stretching Si-O-Si located at 1035 cm\({}^{-1}\)). Another important difference is the increase of Band 20 (from 1562 cm\({}^{-1}\)) (N-H bending of amide II) observed in the CS/PEO/BG spectrum. Analog behavior was detected for Band 21 (1595 cm\({}^{-1}\)) (N-H bending). Another important feature appearing in both spectra is a preponderant peak located at 1634 cm\({}^{-1}\), which corresponds to the imine bond C=N of the Schiff's base structure, which occurred during crosslinking between amino groups of chitosan and aldehyde groups of glutaraldehyde.