Hydroxyapatite matrix (bone surface)

The **hydroxyapatite matrix** is the principal inorganic component of bone, composed of a crystalline mineral form of calcium phosphate (Ca10(PO4)6(OH)2), accounting for about 50% of the bone's weight and conferring rigidity and structural strength[2][7][9]. It is deposited on an organic matrix primarily made up of type I collagen fibers and acts as a scaffold for bone cells. Hydroxyapatite confers mechanical strength, supports bone regeneration, and serves as an anchor for several therapeutic agents and biomaterials in clinical practice[2][5]. The bone surface hydroxyapatite is targeted by drugs like bisphosphonates and radiopharmaceuticals for diseases involving bone remodeling such as osteoporosis and metastatic bone disease. However, as a "target," it is not a molecular entity but rather a mineralized tissue structure[5][7][9].

Other names

Bone mineral matrixBone hydroxyapatiteBone surface hydroxyapatiteBone mineral

Inhibition of bone resorption (e.g., bisphosphonates binding to hydroxyapatite matrix inhibit osteoclast activity) Targeted delivery of therapeutic agents to bone via affinity for hydroxyapatite surfaces (e.g., radiopharmaceuticals, some antibiotics conjugated to bisphosphonates)