Medical professionals use octacalcium phosphate to improve bone repair

Bone repair was largely unsuccessful until the late 1800s. Until then, there was little opportunity to repair major bone damage. Most materials do not have bone functionality and do not support the blood vessels that grow through them.

Repair materials like clay were common, but often failed. In 1892, doctors began using gypsum – calcium sulfate – as the first effective bone replacement material. Bone repair today is much simpler and less risky, but repairing major bone damage remains a challenge.

Today, medical professionals use octacalcium phosphate – OCP – as a replacement bone material. It is a precursor to bone tissue and a logical choice for bone repair. However, medical professionals may not be able to unambiguously assess the full extent of bone damage by X-ray analysis. This can interfere with their ability to accurately predict recovery times and other prognoses for patients.

In a study recently published in Communication chemistry, a team led by researchers from Tokyo Medical and Dental University (TMDU) included a fluorescent molecule – pyromelitic acid in OCP. When used in clinical practice, this advanced modification of OCP will improve diagnostic analyzes and predict therapeutic outcomes.

We included pyromelitic acid by hydrolysis reaction with dicalcium phosphate dihydrate. Analytical characterization and computational analyzes confirmed that we prepared the target material. “

Taishi Yokoi, lead author of the study, Tokyo Medical and Dental University

Their synthetic approach avoided the formation of unwanted salts – calcium carboxylates – which would otherwise interfere with the full functionality of pyromelitic acid. By carefully adjusting the pH and pyromelitic acid concentration during synthesis, the researchers were able to optimize the incorporation of pyromellitic acid into the OCP.

“We found that 81% of the monohydrogen phosphate in OCP was replaced by pyromelitic acid,” says senior author Masakazu Kawashita. “This is important for pyromelitic acid to help bond the various inorganic layers into an intact whole and facilitate complete repair.”

The researcher’s improved bone replacement material was light blue, much lighter than pyromelitic acid when not mixed with bone precursors. This opens up obvious possibilities for real-time visual analysis and will help medical professionals predict the time course of a patient’s recovery and other diagnostic outcomes.

“Our improved OCP has distinct advantages over conventional bone repair materials,” Yokoi explains. “We are optimistic that our material can quickly overcome regulatory barriers in the coming years and find application in dental implants, bone fractures and other demanding surgical applications.”


Tokyo University of Medicine and Dentistry

Journal reference:

Yokoi, T., and others. (2021) Incorporation of tetracarboxylate ions into octacalcium phosphate for the development of biologically acceptable next generation materials. Communication chemistry.