Effect of zinc oxide nanoparticles and light-emitting diode radiation on the viability and differentiation of stem cell derived from human apical papilla

Zinc oxide nanoparticles (ZnONPs) have shown potential in regenerative medicine, particularly when combined with light-emitting diode (LED) radiation. This study aimed to explore the effects of ZnONPs combined with LED radiation on human stem cells derived from the apical papilla (HSCAPs), focusing on primary outcomes of cell viability, odontoblast-like differentiation, and mineralization. This in vitro experimental study utilized ZnONPs synthesized via a green method using pomegranate peel extract. HSCAPs were divided into four groups: control, ZnONPs-only, LED-only, and ZnONPs + LED (experimental group). Cell viability, a primary outcome, was assessed using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay at 24 h. Odontogenic and osteogenic differentiation, evaluated through dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP), alkaline phosphatase (ALP), and dentin matrix acidic phosphoprotein 1 (DMP1) gene expression using qRT-PCR, were assessed on day 7. Mineralization, determined through Alizarin Red S staining, was measured on day 14. The doses used were 1 μg/mL ZnONPs and 620–640 nm range, 85% total emission LED radiation at 5 mW/cm 2 for 30 s, the energy density would be 6 Joules/cm 2 . Statistical analyses were performed using Kruskal–Wallis and dunn’s post hoc tests. (P < 0.05). Cell viability was highest at 1 μg/mL ZnONPs, comparable to control (p > 0.05), and decreased at higher concentrations (p < 0.05). Odontogenic and osteogenic gene expression, including DSPP, ALP, BSP and DMP1was significantly upregulated (p < 0.05) in the ZnONPs + LED group compared to all other groups. Alizarin Red S staining revealed the densest mineralization in the ZnONPs + LED group, followed by LED-only and ZnONPs-only groups. The synergistic application of ZnONPs and LED irradiation significantly enhanced odontogenic and osteogenic differentiation and mineralization of HSCAPs, suggesting their potential utility in endodontic regenerative therapies.