Construction of Hydroxyapatite Gradient Hydrogel Scaffolds by Electrodeposition

To address the challenges of interfacial failure and uncontrolled gradients in traditional osteochondral scaffolds, this study describes an electrodeposition-driven integrated gradient fabrication strategy. Using Carboxymethyl Chitosan-Monosodium Glutamate (CMCS-MSG) as the matrix and Hydroxyapatite (HA) as the functional phase, a controlled gradient of HA (0-6% w/v) was achieved via stepwise electrodeposition and 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC·HCl) cross-linking, under optimized precursor and deposition voltage (pH 8, 3.5 V). The effects of HA content (0-8% w/v) on the electrical conductivity and viscosity of the precursor as well as on the mechanical properties, microstructure, and degradation behavior of the resulting hydrogels (EDGel-H0-EDGel-H8) were systematically investigated. The results demonstrated that when the HA content in the electrodeposition solution was maintained within 0-6% w/v, the compressive stress of the scaffolds at 40% strain increased significantly from approximately 85.9 to 600.3 kPa. Furthermore, EDS and SEM analyses confirmed a uniform HA distribution within each layer and a continuous axial gradient throughout the scaffold. This method not only streamlines the traditional multilayer assembly process but also ensures both mechanical integrity and gradient continuity, providing an efficient solution for the controlled fabrication of gradient cartilage scaffolds. These findings demonstrate a reliable and efficient method for constructing cartilage scaffolds with a controlled HA gradient, offering a feasible approach for mimicking the gradient structure found in natural cartilage.