Photothermal regulation of macrophage polarization with 2D Ti3C2Tx MXene nanosheets for enhanced immunomodulatory osteogenesis

Both pro-inflammatory M1 and anti-inflammatory M2 macrophages play vital roles in the immune response during bone tissue regeneration. Current biomaterials are designed to promote M2 macrophage polarization by manipulating various physical properties. However, this approach lacks precision in controlling the initiation of immunomodulation, potentially leading to premature immune suppression. In this study, the photothermal effect of Ti₃C₂T_x MXene nanosheets under near-infrared (NIR) irradiation was employed to achieve remote regulation of macrophage M2 polarization. Ti₃C₂T_x exhibited excellent photothermal properties and biocompatibility. The mild thermal stimulation produced by photothermal conversion of Ti₃C₂T_x under NIR irradiation promoted macrophage M2 polarization in vitro. Subsequently, these photothermal-polarized macrophages increased the secretion of IL-10 and facilitated the osteogenic differentiation of BMSCs. The synergistic application of Ti₃C₂T_x MXene nanosheets and NIR presents an innovative strategy for remotely modulating macrophage polarization in a temporally controlled manner, thereby paving the way for the development of advanced osteoimmunomodulatory biomaterials.