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(A) SEM image of calcium phosphate salts synthesized on unwashed lamb quarters, unwashed ragweed grains. (B) Before firing and (C) After firing. (D) Calcium phosphate salt synthesized on washed lamb quarters, washed ragweed grains (E) before and (F) after baking. credit: biomimetics (2024). DOI: 10.3390/Biomimetics9030159
A new study shows that pollen grains can be used as a green template for manufacturing biomaterials, showing potential to support drug delivery and bone regeneration.
As the population ages, fractures are becoming more common. Bone is usually able to repair itself, but the use of bone filler may be helpful if the fracture is too large or if the affected person is very fragile, such as someone with osteoporosis.
Hydroxyapatite (HAp) is an inorganic mineral found in human bones and teeth and can be used to support bone regeneration. It accounts for between 65% and 70% of the weight of human bones. Medical professionals often use synthetic and natural HAp when performing bone repair treatments.
The team at the University of Portsmouth has been working with international colleagues to explore sustainable ways to improve the process.
They realized using pollen grains as biotemplates to grow calcium phosphate minerals in the lab, specifically hydroxyapatite (HAp) and β-tricalcium phosphate (TCP), a type of calcium phosphate used in bone repair. We considered the possibilities.
Pollen-like hollow structures show great potential in drug delivery due to their high surface area-to-volume ratio and low density. Organic substances are also resistant to heat and various acids and bases.
Lead author Dr Marta Rold, Associate Professor of Biomaterials in the School of Pharmacy at the University of Portsmouth, said: ‘Pollen plays a critical role in the reproduction of seed plants by protecting their genetic material, which can be damaged by microbial damage, extreme temperatures and dehydration. It has a very resilient outer shell that protects the pollen from environmental damage caused.
“We have shown that this shell can be an effective and sustainable biotemplate for growing life-changing minerals.”
For in vitro studies, ragweed and lamb quarter pollen grains were chosen as templates because of their unique shapes.
The calcification process produced well-defined spherical hollow capsules derived from pollen. After heating and calcination of the capsules, the team was left with calcium phosphate consisting of HAp and TPC.
Characterization techniques used by the research team included X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis.
“We were able to form a sphere with a hollow interior,” Dr. Rold explained.
“Therefore, compared to conventional processes, our product is much lighter and forms internal cavities that have been shown to promote bone mineral deposition in other bone regeneration materials.
“The chemical structure is also a mixture of hydroxyapatite and calcium phosphate, with the latter decomposing very quickly and releasing the ions needed for new bone production, and the former degrading slowly and acting as a reservoir for slowly released ions. Bone regeneration is sustainable in time.”
paper, published in diary biomimeticsstated that further experiments will be needed to explore how these materials can best be used for bone regeneration applications.
Future research will focus on testing whether this new biomimetic material can support enhanced bone integration and regeneration around implants to reduce the likelihood that patients will require reoperation in the future.
For more information:
Arianna De Moe et al, Sporopollenin capsules as biomimetic templates for the synthesis of hydroxyapatite and β-TCP, biomimetics (2024). DOI: 10.3390/Biomimetics9030159
