Concentration-Dependent Effects of MXenes on Viability and Odontogenic Differentiation of Human Dental Pulp Stem Cells.

Background/

Objectives

MXenes (transition metal carbides, nitrides, and carbonitrides) are promising 2D nanomaterials for biomedical applications due to their high conductivity, mechanical strength, and hydrophilicity. This study investigated the concentration-dependent effects of Ti3C2Tx MXenes on the viability, mineralization, and odontogenic differentiation of human dental pulp stem cells (DPSCs).

Methods

Ti3C2Tx MXenes were synthesized and characterized by Scanning Electron Microscope with Energy Dispersive X-ray (SEM/EDX), Dynamic Light Scattering (DLS), zeta potential, UV-Vis, and conductivity analysis. DPSCs were characterized by their mesenchymal stem cell phenotype (CD73+, CD90+, CD105+, CD34-, CD45-). Cells were exposed to 10, 50, and 100 µg/mL MXenes. Cell viability was assessed by (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) MTT assay and apoptosis was evaluated using Annexin V-FITC staining. Mineralization was assessed by Alizarin Red S staining. Odontogenic differentiation was evaluated by qPCR for DSPP, RUNX2, and OCN.

Results

Characterization confirmed successful MXene synthesis with a zeta potential of -22 mV and conductivity of 6110 S/cm. MXenes at 10 and 50 µg/mLmaintained viability above 100%, while 100 µg/mL reduced viability to 65.6% at day 14 (p < 0.01). Apoptosis rates at 10 and 50 µg/mL (5.1% and 6.8%) were not significantly different from the control (4.2%), whereas 100 µg/mL significantly increased apoptosis to 28.4% (p < 0.01). Mineralization was enhanced at 10 and 50 µg/mL (p < 0.05 and p < 0.01) but reduced at 100 µg/mL (p < 0.01). Gene expression of DSPP, RUNX2, and OCN was upregulated 2-3-fold at 10-50 µg/mL but suppressed at 100 µg/mL (p < 0.01).

Conclusions

Ti3C2Tx MXenes exert concentration-dependent effects on DPSCs. Moderate concentrations (10-50 µg/mL) promote metabolic activity, mineralization, and odontogenic differentiation, while high concentrations (100 µg/mL) induce apoptosis and cytotoxicity. These findings support the therapeutic potential of MXenes in regenerative dentistry, provided that concentration thresholds are carefully controlled.