Gelatin Methacryloyl-Adsorbed Calcium Phosphate Nanoparticles for 3D Printing of Bone Repair Scaffolds via Digital Light Processing

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Calcium phosphate (CaP) scaffolds fabricated by using digital light processing (DLP) represent a promising approach to bone tissue engineering and restoration. However, the printability of CaP-based inks is hindered by their low homogeneity and instability, which is attributed to the insufficient compatibility between CaP and GelMA. This study aimed to develop a homogeneous and stable CaP-based ink by adsorbing GelMA onto the surface of CaP nanoparticles (nCaP-GelMA, 320 nm). To achieve this, the interactions between GelMA and nCaP were analyzed, and the effects of GelMA adsorption on the dispersion, stability, and printability of nCaP-based ink were evaluated. Additionally, the cytocompatibility and osteogenic activity of the nCaP-GelMA scaffolds were assessed. The results demonstrated that GelMA was successfully adsorbed onto nCaP through coordinated bonding and electrostatic interactions. The stability of GelMA adsorption was further enhanced by UV irradiation. When GelMA was adsorbed onto nCaP at a weight ratio of 1.2:1, the ink exhibited optimal printability, which was attributed to improved homogeneity and dispersion of nCaP in the GelMA matrix. This advanced CaP-based ink enabled the fabrication of highly accurate, complex, and high-resolution pore structures using DLP. Biocompatibility evaluations confirmed that the nCaP-GelMA scaffolds were noncytotoxic and supported cell adhesion and extension. Moreover, they significantly enhanced osteogenic performance. These findings suggest that DLP-printed nCaP-GelMA scaffolds have significant potential for applications in bone regeneration and orthopedic repair.