Luminescent Hydroxyapatite Nanomaterials for Biomedical Applications

Luminescent hydroxyapatite nanomaterials represent a convergence of bioactive calcium phosphate scaffolds with optical functionality derived from rare‐earth or transition‐metal dopants. Owing to the structural similarity of hydroxyapatite to the mineral phase of bone and teeth, these nanomaterials combine intrinsic biocompatibility, osteoconductivity and degradability with photoluminescent properties suitable for non‐invasive imaging, targeted drug delivery and real‐time tracking of cellular processes. The apatite lattice tolerates substitution of Ca2+ sites by lanthanide ions such as Eu3+, Tb3+ and Gd3+, which impart sharp emission lines and long luminescence lifetimes. Up‐conversion schemes using Yb3+/Tm3+ co‐doping enable near‐infrared excitation and deep tissue penetration, minimising autofluorescence. Surface functionalisation strategies further allow conjugation of therapeutic cargos or targeting ligands, while preserving the apatite’s bioactivity. Collectively, advances in synthesis, dopant control and surface chemistry have transformed luminescent hydroxyapatite into a multifunctional platform for bone‐tissue engineering, cancer theranostics and antimicrobial coatings, with growing evidence of safety and efficacy in cell culture and small‐animal models.

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Luminescent Hydroxyapatite Nanomaterials for Biomedical Applications publication trend

The graph below shows the total number of articles in luminescent hydroxyapatite nanomaterials for biomedical applications across all publications each year (not limited to Nature Index journals).

Technical terms

Hydroxyapatite: A calcium phosphate mineral (Ca10(PO4)6(OH)2) that mimics the inorganic component of bone and enamel, valued for its bioactivity and biocompatibility.

Luminescence: Emission of light by a substance following excitation, including fluorescence, phosphorescence and up-conversion processes.

Doping: The intentional introduction of impurity ions (e.g., Eu3+, Tb3+, Yb3+) into a host crystal lattice to alter its optical or magnetic properties.

Up-conversion: Nonlinear optical process in which two or more low-energy photons (often near-infrared) are absorbed and converted into a higher-energy emitted photon (visible region).

Biocompatibility: The ability of a material to perform with an appropriate host response in a specific biological environment without eliciting adverse reactions.

References

1. Luminescent Hydroxyapatite Doped with Rare Earth Elements for Biomedical Applications. Nanomaterials (2019).
2. Rare-earth (Gd3+,Yb3+/Tm3+, Eu3+) co-doped hydroxyapatite as magnetic, up-conversion and down-conversion materials for multimodal imaging. Scientific Reports (2019).
3. Characterization and Luminescence of Eu3+- and Gd3+-Doped Hydroxyapatite Ca10(PO4)6(OH)2. Crystals (2020).
4. Quenching of the Eu3+ Luminescence by Cu2+ Ions in the Nanosized Hydroxyapatite Designed for Future Bio-Detection. Nanomaterials (2021).