A smart magneto-responsive ternary 3D platform for actively steering stereoscopic infiltration and chronological osteogenic differentiation of BMSCs.

The limited effective infiltration of cells into the interior of scaffolds remains a critical bottleneck limiting the therapeutic application of bone tissue engineering. To address this challenge, this study developed a physically self-assembled ternary smart magneto-responsive composite platform (MGO/CS) based on chitosan, graphene oxide, and superparamagnetic iron oxide nanoparticles (SPIONs). Although the incorporation of SPIONs reduced the mean pore size of the scaffold from 306.64 ± 52.25 μm to 185.39 ± 28.32 μm (p < 0.05), this smart platform, driven by a 3 mT weak static magnetic field (SMF), successfully mitigated the dependence of the three-dimensional colonization of stem cells on pore size, thereby partially overcoming the constraints imposed by conventional geometric topography on deep cell infiltration. By establishing a micro-magnetic environment within the porous scaffold, this magneto-responsive platform may promote BMSC migration across geometric barriers, achieving enhanced deep infiltration throughout the scaffold interior. Furthermore, this intelligent magneto-responsive platform can effectively enhance cellular differentiation signaling, promoting spatiotemporally coordinated osteogenic cascades (characterized by the upregulation of RUNX-2, COL-1, and OPN) and extracellular matrix mineralization. This physical microenvironment modulation strategy mitigates the reliance on geometric topology, offering a novel paradigm for addressing the persistent challenge of insufficient inward cellular infiltration and growth in bone tissue engineering.