## 3 Results and Discussion
### Swelling Ability Study  
To assess the water uptake ability of the membranes, swelling behavior was examined by immersing the samples in phosphate-buffered saline (PBS, pH 7.4) at 37 \({}^{\circ}\)C and measuring weight changes over time (Table 13). Although pure PLA typically shows minimal swelling due to its hydrophobic nature, the exceptionally high swelling degree observed in the PLA nanofiber scaffold (233.7%) can be attributed to several interrelated factors involving its structural configuration and physicochemical interactions with water.  
Electrospun nanofibers possess a high porosity and a large surface-area-to-volume ratio, facilitating rapid water penetration and fluid retention. Additionally, the amorphous regions within the PLA matrix are less densely packed than crystalline regions, allowing more space for water molecules to be absorbed. These findings are consistent with reports from [PERSON] et al. [54], who demonstrated that electrospun PLA mats exhibit significant hydration behavior due to microstructural heterogeneity.  
Moreover, hydrolytic degradation under physiological conditions contributes to the formation of hydrophilic carboxyl and hydroxyl groups, which further enhance water uptake over time. This dynamic was also discussed by [PERSON] et al. [21], who emphasized the role of degradation-induced polarity in boosting scaffold swelling.  
While the incorporation of MgO nanoparticles was expected to increase water uptake due to MgO's hydrophilic character, PLA/MgO membranes (samples 2-4) did not exhibit a consistent improvement in swelling. This discrepancy may result from MgO's encapsulation within the polymer matrix, reducing its direct interaction with water molecules. Furthermore, MgO may contribute to localized structural densification that counters the porosity-related benefits.  
PLA/AuNP membranes (samples 5-7) demonstrated moderate swelling behavior. Among these, sample 5 (0.5 mL AuNPs) exhibited superior swelling capacity compared to higher AuNP-loaded variants. This observation may reflect a threshold beyond which increased AuNP concentration leads to surface aggregation and diminished fluid penetration, consistent with findings from [PERSON] et al. [11] and [PERSON] et al. [12].  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Sample** & **Swelling Degree [\%]** \\ \hline
1 & 233.7 \\
2 & 201.8 \\
3 & 237.1 \\
4 & 75 \\
5 & 232.7 \\
6 & 86.2 \\
7 & 116.8 \\
8 & 46.6 \\
9 & 175.8 \\
10 & 177.1 \\ \hline \hline \end{tabular}
\end{table}
Table 13: Swelling abilities.  
The most pronounced swelling was recorded for PLA/MgO/AuNP hybrid membranes, particularly samples 9 and 10. These formulations benefit from the combined hydrophilic effects and microstructural modifications imparted by both nanoparticles. Their ability to maintain surface wettability and absorb significant volumes of water likely supports cellular migration and nutrient diffusion, thereby improving scaffold integration with host tissue.  
These results confirm that dual functionalization with MgO and AuNPs enhances scaffold swelling capacity, creating a more favorable environment for osteoblast attachment, migration, and tissue regeneration. Enhanced hydration also supports early-stage cellular responses essential for guided bone regeneration, as emphasized in previous studies [29; 31].