Multifunctional Ph-Responsive Nanozymes For Vital Pulp Therapy

This study develops pH-responsive nanozymes to overcome impaired pulp repair in caries-induced pulpitis by sequentially eliminating bacterial infection through enzymatic cascades, modulating inflammatory responses, and promoting hDPSC differentiation, thereby offering an integrated therapeutic strategy for vital pulp preservation. Zn-Fe nanozymes (ZFNs) were synthesized via the solvothermal method. The enzymatic activities of ZFNs at different pH levels were assessed. Antibacterial efficacy against Streptococcus mutans biofilms was quantified through colony-forming unit (CFU) assays. Primary hDPSCs were cultured under four conditions: control, LPS-induced inflammation (10 μg/mL), and LPS with ZFNs treatment (20 or 40 μg/mL). Comprehensive evaluations included: cell viability (CCK-8), intracellular ROS (DCFH-DA), osteogenic differentiation capacity (ALP activity and Alizarin Red S staining), and gene expression analysis (qPCR for inflammatory markers IL-6/IL-1β/TNF-α and mineralization markers RUNX2/OCN/DSPP/DMP-1). ZFNs demonstrated pH-responsive therapeutic effects, with 20 μg/mL combined with 200 μM H₂O₂ achieving 95% S. mutans eradication. Both ZFNs concentrations (20 and 40 μg/mL) significantly enhanced hDPSC proliferation while reducing inflammatory cytokine expression. The ZFNs promoted osteo/odontogenic differentiation, evidenced by increased ALP activity, enhanced mineralization, and upregulated differentiation marker expression in inflammatory conditions(P<0.05). The ZFNs represent pH-responsive nanozymes capable of exhibiting POD-like activity in acidic conditions and CAT-like activity in neutral environments. These nanozymes demonstrate excellent antibacterial properties while effectively mitigating LPS-induced inflammatory damage in hDPSCs and promoting osteogenic/odontogenic differentiation of hDPSCs under inflammatory conditions.