Surface modification of gold nanoparticles with a coumarin derivative for oxidative stress control, antimicrobial efficacy, and tissue regeneration

• Sequential functionalization of AuNPs with lipoic acid, thiosalicylic acid, and 6-aminocoumarin (6AC). • Room-temperature synthesis protocols ensured reproducibility and structural stability. • TEM, XRD, XPS, IR, and thermal analysis confirmed ligand incorporation and surface tuning. • XPS revealed distinct Au–S and amide bonding environments validating 6AC coupling. • Functionalized AuNPs demonstrated enhanced antioxidant, antimicrobial, and biocompatible properties. Functionalized gold nanoparticles (AuNPs) have emerged as versatile platforms in therapeutic research, yet their specific roles in regenerative medicine, particularly in modulating prokaryotic and eukaryotic cell responses, enhancing antioxidant defense, and supporting tissue repair mechanisms, remain insufficiently elucidated. In this study, we have obtained gold nanoparticles initially functionalized with the well-established antioxidant lipoic acid and subsequently with thiosalicylic acid. Their final modification with the 6-amino-chromen-2-one, a coumarin derivative with recognized antioxidant and pharmacological relevance, generated novel composite systems, distinguished by enhanced biological performance. The novel structures have been comprehensively characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), and thermal analysis. Their biological properties were evaluated through antimicrobial and anti-adherence assays against standard and clinical strains, as well as antioxidant and biocompatibility (hemolytic/anti-hemolytic/cytotoxicity) assays. The findings highlight the strong therapeutic potential of functionalized AuNPs, demonstrating enhanced antimicrobial efficacy, antioxidant protection, and cytocompatibility. Their capacity to reduce oxidative stress and combat microbial infections show promise for advanced biomedical applications, such as controlled drug delivery and tissue regeneration.