Hydroxyapatite doped with biosynthesized gold nanoparticles


Hydroxyapatite (HA) and gold nanoparticles (AuNP) are gaining increasing attention in nanotechnology research as serious candidates for widespread application in biomedical technologies. Journal researchers Express material research recently developed a biosynthesized hydroxyapatite gold nanocomposite (Au / HA) which demonstrated enhanced antibacterial and antioxidant activity.

Figure 1. Schematic diagram of the synthesis of Au / HA

To study: Hydroxyapatite doped with biosynthesized gold nanoparticles as an antibacterial and antioxidant nanocomposite. Image: Butterfly pea (Clitoria ternatea), Credit: YuRi Photolife / Shutterstock

Compared to other metallic nanomaterials, gold nanoparticles exhibit high performance qualities against a number of pathogens, as well as antibacterial and antioxidant properties. In recent years, hydroxyapatite has gained increased interest and application in biomedicine due to its resemblance to the mineral part found in human hard tissue found in bones and teeth.

Schematic diagram of Au / HA synthesis. Image Credit: Materials Research Express

Therefore, the development of a new biosynthesized hydroxyapatite gold nanocomposite (Au / HA) is exciting read due to its potential as an innovative material. The main use of the nanocomposite would be applied in the biomedical field.

“The nanocomposite has exhibited antioxidant activity which provides a benchmark for the design and development of novel antibacterial materials for various applications, in particular as an antibacterial component in biomedical technology” said lead author Professor Is Fatimah of Universitas Islam Indonesia.

Nanoparticle biosynthesis is a simple, one-step, environmentally friendly green approach. The biochemical processes of biological agents reduce dissolved metal ions to nanometals. Different biological agents used in the process such as plant tissues, fungi, bacteria, etc. are used for the biosynthesis of metallic nanoparticles.

The researchers developed their nanocomposite by reducing chloroauric acid (HAuCl4), precursor of gold nanoparticles, using a Clitoria ternatea flower extract used in the synthesis of hydroxyapatite. The main objective of the research was to analyze the structure of the composite and to perform antibacterial tests on various strains, including E. Coli.

SEM images and XRF spectra of HA and Au / HA

SEM images and XRF spectra of HA and Au / HA. Image Credit: Materials Research Express

Hydroxyapatite Applications

Hydroxyapatite of biological or synthetic origin is currently applied in scenarios of bone repair and regeneration; typically, a granular form is used in conjunction with scaffold supports. The material can be used on its own or as part of a composite with ceramics, polymers, or even certain groups of metals to help repair or rebuild hard tissue.

As mentioned earlier, the rationale for the use of hydroxyapatite is in part due to the similarity in composition to bone material. In addition to the similarity in composition, hydroxyapatite exhibits good biocompatibility with soft tissues – muscles, skin and gums.

There are many critical bone defects resulting from degenerative disease, high impact trauma, and tumor restriction that cannot be repaired by the body’s natural self-healing mechanisms. Therefore, biotechnological solutions are needed to solve these problems.

However, researchers believe that to overcome some limitations associated with the use of hydroxyapatite, the development of new nanocomposites will help produce more sophisticated and efficient materials to advance practical applications.

Due to rapid advances in nanoscience and nanotechnology, nanoparticle-based biomaterials are increasingly sought after in certain areas of biomedical technology such as tissue engineering.

MET and HRTEM images of HA and Au / HA

MET and HRTEM images of HA and Au / HA. Image Credit: Materials Research Express

Antibacterial gold nanoparticles

Gold nanoparticles are non-toxic and can be easily acquired using various synthetic methods. They show great potential to improve antibacterial effects. This antibacterial effect is the result of the material’s interaction with cellular barriers or biomolecules within bacteria.

While previous research hinted at the therapeutic potential of gold nanoparticles, the true antibacterial effect was seen as a gray area and, in some corners, a controversial claim. However, the advanced characteristics of nanomaterials provide an opportunity to explore and improve their antibacterial activities for clinical applications.

In addition, a growing body of evidence suggests that gold nanoparticles are promising osteoinductive biomaterials for engineering and regeneration of bone tissue. Gold nanoparticles have also been widely used for the preparation of biological therapies, including photothermal therapies, drug delivery systems, diagnostic reagents, biosensors, etc.


Fatimah and her team have found that their nanocomposite serves as a benchmark for the design of antibacterial and antioxidant materials. For comparison, the team tested the biosynthesized nanocomposite against gold nanoparticles and hydroxyapatite alone.

While the gold nanoparticles demonstrated the greatest antibacterial activity, the composite also demonstrated “strong” antibacterial activity which was correlated with the ability of the gold nanoparticles to destroy bacterial membranes.

“The composite has shown that the nanoparticles dispersed in the composite have an influence on the homogeneous performance as well as on the antibacterial activity”, Fatima said.

In addition, the composite has also demonstrated good antioxidant activity, which makes the nanocomposite a good candidate for potential application in the advanced development of artificial organs.

Thus, this research demonstrates an excellent theoretical innovation both in its approach to the biosynthesis of the gold nanocomposite hydroxyapatite as well as in the anticipation of potential clinical uses in the future.

The references:

Est Fatimah, Putwi Widya Citradewi, Amri Yahya, Bambang Nugroho, Habibi Hidayat, Gani Purwiandono, Suresh Sagadevan, Sheikh Ghazali and Shariff Ibrahim, “Hydroxyapatite doped with biosynthesized gold nanoparticles as an antibacterial and antioxidant nanocomposite”, Express research on materials, 2021. https://iopscience.iop.org/article/10.1088/2053-1591/ac3309/meta

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