Hydroxyapatite (HAP) is a major inorganic component of human and animal bones and teeth with the molecular formula Ca10(PO4)10(OH)2. It has good osteoconductivity, biocompatibility and activity, has a high osteogenic potential and is widely used as a bone repair material. With the development of nanotechnology, scientists have found that synthetic hydroxyapatite nanomaterials not only have excellent biocompatibility but also have the advantages of nanomaterials, such as high surface-to-volume ratios, high reactivity and varied microscopic morphologies, making nano-hydroxyapatite promising for nanosystem construction and biomedical applications, while more and more researchers are investigating the application of HAP in cancer therapy.
Fig. 1 Hydroxyapatite crystal structure (Munir, M. U..; et al. 2022).
Anti-tumour Effects of HAP Nanoparticles
Studies have shown that HAP nanoparticles have different degrees of inhibitory effects on the growth of lung cancer, liver cancer, osteosarcoma, stomach cancer and other cancer cells. The main principle is that the release of high concentrations of Ca2+ from HAP nanoparticles can cause cellular dysfunction and induce apoptosis by disrupting telomerase. Researchers have conducted in-depth studies on the anti-tumor effect of HAP nanoparticles and found that their anti-tumor effects are not the same in different tumor cells. In addition, it has been shown that HAP nanoparticles can be used as a drug carrier for cancer therapy. The hollow shape of HAP nanotubes can carry more drugs than normal carriers, and the release of the internal drug can be controlled by pH value.
Application of HAP Nanocomposites in Cancer Therapy
| HAP Nanocomposites |
Description |
| HAP-based nanocomposite scaffolds |
Combining HAP with polymer materials can significantly improve the adaptability of HAP in vivo. Studies have shown that the high specific surface area and biological activity of HAP nanoparticles can endow the composite scaffold with high efficiency in promoting osteogenic differentiation of stem cells. The high near-infrared photothermal conversion efficiency of dopamine endows the composite scaffold with efficient photothermal tumor killing function, and the growth inhibitory effect of the composite scaffold on sarcoma cells is related to time and concentration. |
| HAP microcapsules based on layer-by-layer self-assembly technology |
The researchers used a layer-by-layer self-assembly technique to prepare remotely controllable hollow microcapsules with the intelligent response using hollow hydroxyapatite, chitosan/hyaluronic acid polyelectrolyte multilayers and gold nanorods. In vitro cytotoxicity assays showed that the hybrid microcapsules exhibited excellent in vitro cytocompatibility, and drug release assays showed that the hybrid microcapsules exhibited a high drug loading rate and significant NIR/ pH synergistic drug release performance. |
| Actively targeting HAP nanocomplexes |
Nano-mesoporous apatite has both the unique properties of mesoporous materials and the excellent biocompatibility of nano-apatite and has essential application prospects. A reduction-responsive mesoporous apatite/collagen nanocomposite release system and a pH-responsive mesoporous apatite/bovine serum albumin nanocomposite release system were constructed using mesoporous apatite nanoparticles by researchers. It has been shown that both systems have good cellular biocompatibility, can be continuously engulfed by hepatocellular carcinoma cells and release functional drugs in the cytoplasm pH-responsive after endocytosis. Both systems have the ability to specifically target hepatocellular carcinoma cells due to the specific binding of lactic acid molecules to ligands on the membrane surface of hepatocellular carcinoma cells. |
Reference
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Munir, M. U.; et al. Synthesis, characterization, functionalization and bio-applications of hydroxyapatite nanomaterials: an overview. International Journal of Nanomedicine. 2022, 1903-1925.
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