Multifaceted CPG nanocomposites combine MMPs suppression and remineralization shielding to augment dentin bond durability

While carbon nanotubes (CNTs) have demonstrated substantial dentin adhesion enhancement through collagen fiber reinforcement leveraging their exceptional mechanical strength, their capacity to sustain dentin bond durability remains fundamentally constrained due to enzymatic degradation and mineral loss. We aimed to fabricate polydopamine/gelatin-functionalized CNTs (CPG) and evaluate their effects on matrix metalloproteinase (MMP) inhibition, dentin remineralization, and the stability of resin-dentin bonding interfaces. CPG nanocomposites were synthesized via dopamine self-polymerization and Michael addition. The MMP inhibitory capacity was assessed by colorimetric activity assay, hydroxyproline (HYP) release quantification and in situ zymography. Dentin remineralization and microstructure were characterized by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Microtensile bond strength testing and nanoleakage analysis were performed to evaluate the immediate and long-term dentin bonding performance. CPG exhibited multifaceted efficacy primarily through dose-dependent MMP suppression (about 44% enzyme activity inhibition at 50 µg/mL). Moreover, it was revealed that CPG promotes intrafibrillar mineralization by constructing collagen fibers and collagen fiber membrane models. CPG enhanced immediate bond strength by ~ 48% and maintained ~ 93% retention after 3-month aging, with significantly reduced interfacial nanoleakage compared with the control group. The CPG nanocomposite simultaneously inhibits MMP-mediated collagen degradation and promotes dentin remineralization, effectively enhancing the immediate strength and long-term durability of dentin bonding. This bioactive nanoplatform provides a feasible strategy for extending the service life of dental restorations.