Polylysine-derived carbon quantum dots modulate T lymphocyte responses for periodontitis treatment

[Display omitted] •The prepared PL-CQDs had uniform particle size, fluorescent properties, and positive charge.•Biocompatible PL-CQDs enhanced T cell viability with increasing concentration and inhibit T cell differentiation to CD4 + T cells in mice.•PL-CQDs, together with T cells, promoted osteogenic differentiation of MC3T3-E1 cells and promoted alkaline phosphatase expression and calcium nodule formation in MC3T3-E1 cells.•In vivo, PL-CQDs promoted periodontal bone formation, reduced periodontal tissue inflammation, and had good therapeutic effects in animal models. Periodontitis, a common chronic inflammatory disease, is characterized by T cell responses leading to gradual alveolar bone loss and eventual tooth mobility or loss. Herein, polylysine-derived carbon quantum dots (PLL-CQDs) are synthesized via the pyrolysis method to facilitate the recovery of periodontal bone loss induced by periodontitis by modulating T cell phenotype. The PLL-CQDs, characterized by small particle size (2.31 ± 0.70 nm) and fluorescence properties, preserved the positive charge of PLL, affirming successful preparation. In vitro studies revealed that PLL-CQDs significantly increased T cell proliferation in a concentration-dependent manner, while effectively suppressing differentiation into CD4+ phenotype. Furthermore, they promoted alkaline phosphatase expression and calcium nodule formation in MC3T3-E1 cells, indicating potential for periodontal bone regeneration. In vivo experiments demonstrated that PLL-CQDs mitigated alveolar bone resorption and modulated periodontal tissue inflammation. Overall, PLL-CQDs exhibited the ability to regulate T cell differentiation and expedite periodontal bone healing, offering promising implications for periodontitis treatment and suggesting novel strategies for addressing immune-associated bone diseases using CQDs.