## 3 Results and Discussion
The development of HA on the surface of BG-V is confirmed by the presence of the following diffraction peaks at 0 = 25.9\({}^{\circ}\), 31.6\({}^{\circ}\), 32.2\({}^{\circ}\), 32.7\({}^{\circ}\), and 39.7\({}^{\circ}\), corresponding to the (002), (211), and (310) reflections of the HCA crystals [30]. Hydroxyapatite (HA) is the mineral component of bone and, based on the International Centre for Diffraction Data (ICDF) 09-0432, when detected through XRD different peaks, will appear at 25.87\({}^{\circ}\), 31.77\({}^{\circ}\), 32.19\({}^{\circ}\), 32.9\({}^{\circ}\), and 39.81\({}^{\circ}\) representing the (h, k, l) diffraction planes (002), (211), (300), and (310), respectively. Additionally, peaks appearing at 0 45.3\({}^{\circ}\), 46.5\({}^{\circ}\), 49.4\({}^{\circ}\), and 53.2\({}^{\circ}\) represent the (203), (222), (213), (004), and (422), respectively [21]. After drug release in PBS, BG-V shows incredible bioactivity, indicating that the glass is biodegradation as it releases the loaded vancomycin in vitro. The deposition of HA on BG-V emphasizes its suitability for bone regeneration and antimicrobial applications, demonstrating its dual function of enhancing bone integration while mitigating bacteria. The bioactivity of BG-V, as observed in the XRD spectra, aligns with previous studies where HA formation on the surface of bioactive glass confirmed bioactivity. This mirrors the findings of [PERSON] et al. (2019) [31], who observed bioactivity on sol-gel (58S) bioactive glass after 2 days, noting that the peaks become sharper with longer soaking time. Further supporting these observations, [PERSON] et al. (2021) [32], demonstrated that 58S bioactive glass prepared by a hydrothermal, acid-free process developed HA within just 1 day, as shown by two prominent XRD peaks at 26\({}^{\circ}\) and 32\({}^{\circ}\), which intensified with prolonged soaking time. These consistent findings across different synthesis methods highlight the HA-forming capability of SiO\({}_{2}\)-CaO\({}_{2}\)-PO\({}_{5}\) systems and validate BG-V's surface reactivity. The parallels in XRD patterns between these studies and this study confirm the reliability of the bioactivity assessment performed here. The nitrogen adsorption-desorption graph shown in Figure 4 represents the BG-V before drug release (black). It is observed that the graph shows a type IV isotherm with no hysteresis, indicating that there is a lower surface area as the pores are blocked by the adsorption of vancomycin onto the BG. The second graph in red shows that after the drug is released, the isotherm observed is type IV with hysteresis, indicating a vertically oriented horn-shaped pore [33]. This shows that following drug release, the pores of BG-V open and  
Figure 3: (**a**) XRD of vancomycin (blue) and BG-V before drug release in PBS (black) and after drug release studies (red); (**b**) shows BG-V and BG. The peaks marked with * indicate HA development on the surface of BG-V.  
the surface area increases; this aids in the gradual release of the vancomycin from the BG as it allows it to release the physically adsorbed drug followed by the entrapped drug that is being held by hydrogen bonds. The development of hydroxyapatite on the surface of BG also contributes to the increase in the surface area, as the silanol layer (Si-OH) is converted into HA. Table 1 presents the data obtained from BET analysis, including surface area, pore volume, and pore size. Measurements were taken both before and after the drug release test to evaluate changes over time. A significant increase in surface area is observed from before the drug release and after. On day 0, the surface area was measured at 20.23 m\({}^{2}\)/g, which increased to 156.64 m\({}^{2}\)/g after drug release, suggesting pore opening and drug release. This increase may also indicate the formation of HA on the surface or pore widening due to the biodegradation of BG-V when immersed in PBS. The results further reveal changes in pore volume.