In vitro and in vivo evaluation of graphene oxide–gold nanocomposites for enhanced biocompatibility and functional performance in biomaterial application

Gold-functionalized graphene oxide (GO-Au) nanocomposites were synthesized and comprehensively characterized to assess their physicochemical properties and biomedical efficacy. UV-Vis spectroscopy revealed a distinct surface plasmon resonance peak at ∼524 nm, confirming successful Au nanoparticle (AuNP) incorporation. FTIR analysis showed shifts in O–H and C[dbnd]O vibrational bands, indicating interactions between AuNPs and the oxygen-containing groups on GO. Among all tested formulations, GO-Au at 12.2 ppm exhibited optimal morphology, the highest antioxidant activity (92 % DPPH radical scavenging), and improved hydrophilicity. 1 H NMR spectroscopy demonstrated a reduction in signal intensity within the 1.45–2.13 ppm range, suggesting selective interactions between AuNPs and aliphatic oxygenated groups, while preserving the aromatic regions of GO. XPS analysis confirmed the presence of Au through Au 4 f peaks at 84 eV, along with characteristic C 1 s, O 1 s, and N 1 s signals. No Au peaks were observed in pristine GO. In vitro, GO-Au 12.2 ppm significantly enhanced bovine aortic endothelial cell (BAEC) proliferation at 24, 48, and 72 h (1.15, 1.27-, and 1.43-fold; p < 0.001) and promoted migration (2.32- and 3.45-fold at 24 and 48 h), accompanied by elevated MMP-2 (1.58-fold) and MMP-9 (1.49-fold) activity. In contrast, Raw 264.7 macrophages showed marked reductions in viability (0.60-, 0.55-, and 0.63-fold) and pro-inflammatory cytokine secretion (TNF-α, IL-1β, IL-6; all p < 0.001), indicating potent anti-inflammatory effects. GO-Au 12.2 ppm also facilitated mesenchymal stem cell (MSC) differentiation, significantly increasing expression of endothelial markers CD31 (1.76-fold) and vWF (1.53-fold), as well as neural markers nestin (1.62-fold), GFAP (1.78-fold), and β-tubulin (2.03-fold; all p < 0.001). In vivo, subcutaneous implantation of GO-Au 12.2 ppm in rats for 4 weeks demonstrated reduced fibrous capsule thickness (0.72-fold), collagen deposition (0.69-fold), and apoptosis (0.65-fold; p < 0.01). Immunofluorescence revealed increased CD31 (1.86-fold), decreased CD45 (0.58-fold) and CD86 (0.49-fold), and elevated CD163 (1.70-fold), reflecting enhanced angiogenesis and an anti-inflammatory microenvironment. Collectively, these findings establish GO-Au 12.2 ppm as a promising nanoplatform with superior cytocompatibility, immunomodulatory function, and regenerative efficacy, supporting its potential in tissue engineering and regenerative medicine.