## 3 Results and Discussion
### In Vitro Biodegradation Evaluation  
Biodegradation is a critical factor in guided bone regeneration (GBR) applications, as membranes must retain mechanical integrity during the healing phase and subsequently degrade to permit bone tissue infiltration. In this study, degradation behavior was assessed through two main parameters: mass loss over time and pH stability of the degradation medium (Table 14). Membranes were immersed in simulated body fluid (SBF, pH 7.4, 37 \({}^{\circ}\)C) for 1, 7, 14, and 21 days, followed by drying and weighing to evaluate their degradation profile. Pure PLA membranes (sample 1) exhibited a degradation rate of 10.8% \(\pm\) 0.9, which, while lower than expected from the previous literature, still reflects the polymer's inherent hydrolytic instability over time. This value is consistent with initial breakdown of ester bonds leading to modest mass loss. The incorporation of MgO into the PLA matrix (samples 2-4) resulted in progressive increases in degradation: 11.3% \(\pm\) 1.1 for sample 2, 13.3% \(\pm\) 1.0 for sample 3, and 17.7% \(\pm\) 1.3 for sample 4. These values suggest that while MgO may initially buffer degradation byproducts, at higher concentrations, it may also influence microstructural organization and porosity, ultimately accelerating fluid penetration and hydrolysis. This dual role has been described in studies where inorganic additives both stabilize local pH and alter scaffold permeability [22; 34]. PLA/AuNP membranes (samples 5-7) demonstrated degradation values of 12.8% \(\pm\) 0.8, 13.6% \(\pm\) 1.0, and 14.4% \(\pm\) 0.9, respectively. These findings confirm that AuNPs, while biologically active, do not significantly inhibit degradation. Rather, they may slightly contribute to mass loss by influencing fiber morphology and localized interactions with the aqueous medium. These results align with those of [PERSON] et al. [12], who observed modest increases in PLA degradation with AuNP inclusion. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Biodegradation**} \\ \hline \multirow{2}{*}{**Sample**} & **Weight** & **Initial pH** & **pH After** & **pH After** & **pH After** & **pH After** \\  & **Loss [\%]** & & **24 h** & **7 Days** & **14 Days** & **21 Days** \\ \hline
1 & 10.8 & & 7.4 & 7.49 & 7.60 & 7.38 \\
2 & 11.3 & & 7.52 & 7.60 & 7.71 & 7.53 \\
3 & 13.3 & & 7.56 & 7.73 & 7  
The PLA/MgO/AuNP hybrid membranes (samples 8-10) showed the most substantial degradation values: 16.9% \(\pm\) 1.1 for sample 8, 19.0% \(\pm\) 1.2 for sample 9, and 21.1% \(\pm\) 1.4 for sample 10. While these values are higher than those for pure PLA, they reflect a balanced degradation profile when considering the overall scaffold performance. In these dual-modified samples, MgO provides buffering against acidic byproducts, while the inclusion of both nanoparticles modifies porosity and surface accessibility, contributing to a controlled degradation pace beneficial for GBR. Comparable synergistic effects have been demonstrated in dual-inorganic composite scaffolds designed for staged degradation and tissue remodeling [10; 11; 30]. To complement mass loss data, pH monitoring of the SBF medium was conducted to assess acidification trends due to PLA hydrolysis. Sample 1 showed a slight pH drop to 7.38, indicating limited acidification. In contrast, MgO-containing samples (2-4) maintained pH levels near 7.54, consistent with MgO's role as a buffering agent. Samples with AuNPs (5-7) tracked closely with the control, showing minor pH variation. Dual-functionalized membranes (8-10) maintained the most stable pH, ranging from 7.5 to 7.87, further affirming MgO's effectiveness in mitigating acidic degradation effects. These findings highlight that while MgO enhances pH buffering and AuNPs modulate surface chemistry, both contribute to scaffold degradation profiles in different ways.