Synergistic effect of low-dose gamma radiation and/or clove oil loaded on silica nanoparticles on regeneration of human gingival fibroblast cell line: an in vitro study

In light of the growing use of natural products in medicinal therapy, this study evaluated the proliferative effects of clove oil (CO) in two forms-native and loaded onto silica nanoparticles (CO@SNPs)-on Human Gingival Fibroblasts (HGFs), both singly and in combination with low-dose gamma irradiation (0.25 Gy). Silica nanoparticles were chemically synthesized and loaded with clove oil, with thorough characterization conducted using dynamic light scattering (DLS) for particle size, zeta-potential measurements, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The EC50 values of CO and CO@SNPs were determined to be 1.88 µmol/mL and 0.172 µmol/mL, respectively, demonstrating a superior proliferative efficacy of the CO@SNPs nanoformulation. The biological effects were assessed using the MTT assay for cell viability, Trypan blue exclusion for cell count, qPCR for gene expression of c-Myc, MAPK, and NF-κB, and antioxidant capacity assays (MDA and catalase activity). Moreover, the in vitro wound-healing scratch assay showed enhanced fibroblast migration and proliferation, with relative wound density reaching 48% and 62% for CO@SNPs alone and combined with low-dose gamma irradiation, respectively. Further analysis through immunofluorescence staining of TGF-β and hematoxylin staining confirmed cell proliferation. Our results showed that loading CO on silica nanoparticles (CO@SNPs) were significantly more efficient than native clove oil in promoting cell proliferation and wound healing, with the combined treatment of CO@SNPs and low-dose gamma irradiation producing the most pronounced regenerative effect. These findings suggest that CO@SNPs, especially when combined with low-dose gamma irradiation, hold significant promise for enhancing oral tissue regeneration.