Injectable biocomposite cement: A dual-setting formula with magnesium potassium phosphate and κ-carrageenan hydrogel for orthopedic advancements.

Magnesium phosphate-based cements are highly regarded for their bioactive properties, making them excellent candidates as bone substitutes. Despite their promising attributes, challenges such as high reaction temperature, limited injectability, and brittleness limit their application. This study introduces a dual-setting biocomposite cement, which encompasses both cement hydration and hydrogel's cross-linking. The composition features magnesium potassium phosphate (MKP) combined with ionically cross-linked kappa-carrageenan (kC) plasticized with sorbitol (Sor). The investigation delves into the properties of the resultant biocomposite, with a particular focus on evaluating kC incorporation's influence on the main MKP properties. Our findings reveal that those biocomposites offer multiple benefits over traditional ceramic cements. The main advantages include: a longer setting time (up to 15 min), lower setting temperature (45 °C), different crystalline phase (bobierrite), better wettability (~22°), and improved injectability of the paste characterized by more stable cohesion. Specifically, the MKP (4:1 Mg/P ratio) with 1.5 % kC and Sor hydrogel obtained with 3.0 g/mL powder-to-liquid ratio demonstrated the most promising properties with no adverse effects on the microstructure diversity, the mechanical strength, the porosity, the biodegradation rate, and the osteoblasts cytocompatibility. Overall, our research indicates that these innovative cements hold significant potential for biomedical applications, especially minimally invasive orthopedic procedures.