Green-Synthesized Curcuma longa-Derived Silver Nanoparticles for Oral Biomaterial Applications: Physicochemical
Mhd Kher Alsaeyd Ahmad1, Doina Chioran2, Dana-Emanuela Pitic Coţ2
1Doctoral School of Dental Medicine, "Victor Babeş" University of Medicine and Pharmacy, Revolutiei Ave. 1989, No. 9, 300580 Timisoara, Romania.
Background/Objectives:
Plant-mediated silver nanoparticles (AgNPs) are promising components for oral biomaterials because of their antimicrobial potential; however, their biological behavior depends strongly on the phytochemical matrix, physicochemical characteristics, and exposure concentration. This study aimed to evaluate silver nanoparticles formulations synthesized using turmeric powder-derived Curcuma longa ethanolic and aqueous extracts, with emphasis on physicochemical characterization, antibacterial activity against oral-relevant Gram-positive bacteria, cytocompatibility toward human gingival fibroblasts (HGF-1), and acute in ovo vascular compatibility.
Methods:
AgCUR-EtOH NPs and AgCUR-H2O NPs were synthesized using CUR-EtOH and CUR-H2O extracts as reducing and stabilizing matrices. The resulting formulations were characterized by UV-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), zeta-potential analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined against Streptococcus mutans, Streptococcus oralis, and Staphylococcus aureus. Cytocompatibility was evaluated in HGF-1 human gingival fibroblasts after 24 h exposure to 1-10 µg/mL using complementary viability, lysosomal, mitochondrial, and fluorescence-based assays. Acute vascular irritation was assessed using the hen's egg test-chorioallantoic membrane (HET-CAM) assay.
Results:
Both formulations exhibited broad, polydisperse hydrodynamic distributions and negative apparent zeta potentials. AgCUR-H2O NPs showed a lower Z-average diameter than AgCUR-EtOH NPs under their respective solvent-specific measurement conditions. XRD pattern revealed heterogeneous crystalline compositions dominated by residual AgNO3, together with weaker contributions consistent with metallic Ag and a possible minor oxidized silver phase. FTIR spectra demonstrated extract-derived organic functional groups and prominent nitrate-associated bands. TEM/EDX confirmed Ag-containing nanostructures with approximate size ranges of 15-175 nm for AgCUR-EtOH NPs and 15-150 nm for AgCUR-H2O NPs. S. mutans was the most susceptible microorganism, with MIC values of 9 and 7 µg/mL and MBC values of 88 and 62 µg/mL for AgCUR-EtOH NPs and AgCUR-H2O NPs, respectively. AgCUR-H2O NPs consistently showed lower MIC and MBC values against all tested strains, but also produced a more pronounced concentration-dependent reduction in HGF-1 viability. At 10 µg/mL, cell viability was 71.88% for AgCUR-EtOH NPs and 52.14% for AgCUR-H2O NPs. Both formulations showed low acute irritation potential in ovo, with irritation scores of 1.06 and 0.69, respectively.
Conclusions:
The two CUR-AgNP formulations exhibited distinct physicochemical, antibacterial, and cellular response profiles under the tested conditions. At equivalent concentrations expressed as total dried formulation mass, AgCUR-H2O NPs yielded lower MIC and MBC values against the tested bacterial strains, whereas AgCUR-EtOH NPs produced a less pronounced reduction in HGF-1 viability. Because the powders were not quantitatively normalized for total silver, extract-derived organic fraction, or residual precursor content, these differences cannot be attributed exclusively to nanoparticle properties or to the extraction solvent and should not be interpreted as evidence of the intrinsic superiority of either formulation. Both formulations showed low acute vascular irritation. Further quantitative compositional, silver-release, and biofilm assessments are required before incorporation into oral biomaterial platforms.