A 3D-Printed copper-doped hydroxyapatite/alginate Scaffold functionalized with L-arginine for antibacterial, angiogenic, osteogenic, and photothermal stimulation

Critical-sized bone defects require advanced grafts that simultaneously address regeneration, vascularization, and infection. This study presents a multifunctional 3D-printed scaffold designed for coordinated bone healing, composed of alginate reinforced with copper-doped hydroxyapatite (Cu-HA) nanoparticles and post-functionalized with L-arginine (Arg). Physicochemical analyses confirmed successful fabrication of scaffolds with controlled porosity and a compressive modulus of 1.6–2.6 GPa, suitable for cancellous bone. Furthermore, the Cu-HA composition endowed the scaffold with a significant and controllable photothermal response under 808 nm irradiation, producing a temperature rise of up to 26 °C in the hydrated state. The scaffolds also demonstrated enhanced protein adsorption and a potent, copper-dependent antibacterial effect. In vitro biological evaluation revealed a multifaceted pro-angiogenic response: scaffold extracts significantly stimulated endothelial cell migration in a scratch assay and potently enhanced tubulogenesis on Matrigel; the addition of Arg induced a distinct morphological shift towards elongated, stabilized cellular networks. Regarding osteogenesis, elevated Cu 2+ levels accelerated the differentiation timeline, and the combination of Arg and Cu 2+ robustly upregulated expression of collagen I and osteopontin. By integrating structural support with demonstrated antibacterial, angiogenic, osteogenic, and photothermal functionalities, this scaffold represents a promising multi-stimuli platform for complex bone tissue engineering applications.