Bridging bioceramics and advanced 2D/porous materials: a review of hydroxyapatite/metal-organic framework and hydroxyapatite/MXene composites.

Hydroxyapatite (HAp) is a well-known bioceramic material with excellent biocompatibility, bioactivity, and chemical stability. However, its brittleness, low surface reactivity, and limited functionality restrict its use in advanced applications such as drug delivery, catalysis, and sensing. To overcome these limitations, HAp has recently been combined with metal-organic frameworks (MOFs) and MXenes, two emerging classes of functional materials. MOFs provide high surface area and tunable porosity, whereas MXenes offer excellent electrical conductivity and photothermal properties. In turn, HAp enhances the structural stability of these materials by improving the moisture resistance of MOFs and reducing the restacking tendency of MXenes. In both types of composites, HAp primarily acts as a bioactive and ion-rich support, while the MOF or MXene component provides the desired functional properties. This common design strategy forms the basis of the present review, which is the first to comparatively discuss HAp/MOF and HAp/MXene composites within a single framework. The review summarizes their synthesis methods and applications in biomedical engineering, environmental remediation, catalysis, electrochemical sensing, coatings, and agriculture. More importantly, it critically examines whether the reported performance improvements arise from true synergistic interactions or simply from the individual contributions of each component. It also compares the reproducibility of different fabrication strategies, discusses the distinct mechanisms through which HAp improves the stability of MOFs and MXenes, and evaluates the maturity of reported applications based on real-sample testing and