Inspired by the mussel’s ability to very tightly attach itself to even metallic surfaces using unique proteins found in its byssal threads, a team of researchers from RIKEN have managed to attach a biologically active molecule to a titanium surface. This achievement is likely to open doors for implants that can be more biologically beneficial.
Titanium has been used in medical applications such as dental implants and artificial joints. Although titanium is not harmful to tissues and strong, it lacks certain of the beneficial biological properties of natural tissues such as natural teeth and bones.
The researchers’ work is based on former discoveries that mussels have the capacity to attach themselves to smooth surfaces because of a protein called as L-DOPA. It is known that this protein can strongly attach to smooth surfaces such as ceramics, rocks, or metals.
The same protein acts as a precursor to dopamine in humans. It is also used as a treatment for Parkinson’s disease.
We thought it would be interesting to try to use various techniques to attach a biologically active protein—in our case we chose insulin-like growth factor-1, a promoter of cell proliferation—to a titanium surface like those used in implants.
Chen Zhang of the RIKEN Nano Medical Engineering Laboratory, the first author of the paper published in Angewandte Chemie
The team successfully developed a hybrid protein that possessed active parts of both the L-DOPA and the growth factor using a blend of treatment with tyrosinase and recombinant DNA technology. Tests revealed that the proteins had folded normally, and additional experiments in cell cultures illustrated that the IGF-1 continued to function as it should.
The success of the research was mainly due to the addition of the L-DOPA. The team was able to prove that the proteins attached strongly to the titanium surface, and stayed attached despite the metal being washed with a water-based solution - phosphate-buffered saline.
This is similar to the powerful properties of mussel adhesive, which can remain fixed to metallic materials even underwater.
We are very excited by this finding, because the modification process is a universal one that could be used with other proteins. It could allow us to prepare new cell-growth enhancing materials, with potential applications in cell culture systems and regenerative medicine. And it is particularly interesting that this is an example of biomimetics, where nature can teach us new ways to do things. The mussel has given us insights that could be used to allow us to live healthier lives.
Yoshihiro Ito, Team Leader of the Emergent Bioengineering Research Team of the RIKEN Center for Emergent Matter Scien