## 3 Results and Discussion
### FT-IR Analysis  
The FT-IR spectrum analysis (Figure 13) of polylactic acid (PLA) nanofibers enables the identification of characteristic absorption bands associated with specific functional groups in the polymer matrix. A prominent band in the range of 1750-1740 cm\({}^{-1}\) corresponds to the stretching vibrations of ester bonds (-C=O), a defining structural component of PLA. Additionally, distinct bands in the regions of 1180-1080 cm\({}^{-1}\) and 1450-1350 cm\({}^{-1}\) are attributed to the stretching and deformation vibrations of the C-O-C backbone and methyl (-CH\({}_{3}\)) groups, respectively. These features confirm the presence of the characteristic aliphatic polyester structure, consistent with the prior literature on PLA infrared spectra [13; 17]. Upon incorporation of periclase (MgO), new vibrational signatures emerge in the 1000-800 cm\({}^{-1}\) region, indicating metal-oxygen (Mg-O) interactions. These peaks are attributed to symmetric and asymmetric stretching modes of Mg-O bonds, which signify successful nanoparticle dispersion within the polymer matrix. Similar spectral features have been reported by [PERSON] et al. [8], who observed analogous Mg-O bands in magnesium-based composites for bone regeneration. The presence of these signals confirms that MgO nanoparticles are retained post-electrospinning and contribute to chemical heterogeneity within the scaffold.  
Moreover, the integration of MgO induced minor shifts in the PLA's primary absorption bands, particularly a downward shift in the ester C=O band. This is indicative of potential intermolecular interactions, such as hydrogen bonding or dipolar interactions between MgO and PLA functional groups, consistent with observations made by [PERSON] et al. [54] in composite PLA systems.  
Gold nanoparticles (AuNPs), when embedded into PLA nanofibers, introduced additional absorbance features in the 500-1500 cm\({}^{-1}\) region. While AuNPs themselves exhibit limited direct IR activity due to their metallic nature, their presence can modulate the polymer environment and influence vibrational modes indirectly. In this study, subtle modifications in the intensity of C=O and C-O peaks were observed, likely due to changes in bond polarizability or surface interactions between the gold nanoparticles and ester groups. Such effects have been attributed to localized surface plasmon resonance phenomena and  
Figure 13: FT-IR spectrum of sample 10 (PLA + 0.5 g MgO + 2 mL AuNPs).  
nanoscale interface interactions in earlier work by [PERSON] et al. [11] and [PERSON] et al. [10]. Of particular interest is the observed shift in the C=O peak toward lower wavenumbers in dual-modified samples, which suggests stronger dipole-dipole interactions or electron delocalization at the nanoparticle-polymer interface. These findings support the hypothesis that AuNPs engage in weak bonding or electrostatic interactions with the PLA matrix, influencing the structural integrity and potential bioactivity of the fibers. This is in agreement with previous studies on AuNP-polymer hybrid systems demonstrating tunable interfacial chemistry [11; 12]. The collected FT-IR data provide compelling evidence for the successful integration and distribution of both MgO and AuNPs within the PLA nanofibers. More importantly, they underscore the presence of molecular-level interactions that can potentially affect the scaffold's mechanical behavior, degradation profile, and biological performance. In the context of biomedical engineering and guided bone regeneration, such chemical insights are crucial for designing responsive and functionalized biomaterials tailored for osteogenic stimulation and in vivo stability [34; 35].