Calcium Phosphate Biomaterials for Bone Tissue Engineering

Calcium phosphate materials occupy a central role in bone tissue engineering owing to their close chemical resemblance to the mineral phase of natural bone, inherent biocompatibility and tunable resorption rates. Hydroxyapatite and tricalcium phosphate in particular have been formulated into porous scaffolds, cements and coatings that support osteoblast attachment, proliferation and new bone formation. Control of phase composition, crystallinity and microstructure enables fine adjustment of mechanical properties and degradation kinetics, facilitating the synchrony between scaffold resorption and tissue ingrowth. Emerging strategies harness ion substitution, composite architectures and advanced fabrication techniques such as three-dimensional bioprinting to enhance osteoinduction, vascular integration and local delivery of bioactive agents. Collectively, these advances are underpinning the development of next-generation implants and grafts that more faithfully replicate native bone structure and function, with wide implications for fracture repair, defect reconstruction and personalised regenerative therapies.

Research from Nature Portfolio

Recent studies have provided atomic-scale insight into the interplay between non-collagenous proteins and octacalcium phosphate during early bone mineralisation, revealing how osteocalcin binds to specific calcium sites and suppresses hydroxyapatite overgrowth to guide collagen fibril mineralisation. In parallel, chemical functionalisation of octacalcium phosphate via incorporation of tetracarboxylate ions has been shown to impart novel optical and binding properties while preserving its layered structure, opening avenues for smart biomaterials that combine mineral templating with tailored bioactivity.

Research from all publishers

Innovations in calcium phosphate synthesis include a thermodynamic-modelling-assisted, three-stage solid-state route yielding β-tricalcium phosphate powders of over 99 per cent purity, homogenous morphology and reproducible crystallinity, optimised for use in bone graft substitutes. Multifunctional hollow calcium phosphate microcapsules have been engineered as drug delivery excipients, featuring a porous shell that affords high water uptake and structural integrity during tablet compaction, with potential to co-deliver osteogenic factors. Additionally, octacalcium phosphate has been advanced as a vehicle for localised release of biologically active ions and molecules, exploiting its interlayer spaces and high solubility to achieve controlled, osteoconductive delivery in bone defect environments.

Calcium Phosphate Biomaterials for Bone Tissue Engineering publication trend

The graph below shows the total number of articles in calcium phosphate biomaterials for bone tissue engineering across all publications each year (not limited to Nature Index journals).

Technical terms

Hydroxyapatite: A calcium phosphate mineral (Ca₁₀(PO₄)₆(OH)₂) that replicates the inorganic phase of bone, offering biocompatibility and osteoconductivity.

Tricalcium phosphate (TCP): A resorbable ceramic (Ca₃(PO₄)₂) available in α and β polymorphs, commonly used as bone grafts and cements.

Octacalcium phosphate (OCP): A hydrated precursor phase (Ca₈(HPO₄)₂(PO₄)₄·5H₂O) that transforms into hydroxyapatite and accommodates ion or molecule incorporation.

Scaffold: A three-dimensional porous framework designed to support cell adhesion, proliferation and new tissue formation.

References

1. First evidence of octacalcium phosphate@osteocalcin nanocomplex as skeletal bone component directing collagen triple–helix nanofibril mineralization. Scientific Reports (2018).
2. Incorporation of tetracarboxylate ions into octacalcium phosphate for the development of next-generation biofriendly materials. Communications Chemistry (2021).
3. Thermodynamic modelling assisted three-stage solid state synthesis of high purity β-Ca3(PO4)2. Materials & Design (2024).
4. Calcium Phosphate Microcapsules as Multifunctional Drug Delivery Devices. Advanced Functional Materials (2023).
5. Octacalcium phosphate: Innovative vehicle for the local biologically active substance delivery in bone regeneration. Acta Biomaterialia (2021).