RIKEN scientists have successfully attached a biologically active molecule to a titanium surface using insight from mussels, which are able to attach themselves very tightly to even metallic surfaces due to special proteins found in their byssal threads.
Titanium is used medically in applications such as artificial joints and dental implants. While it is strong and is not harmful to tissues, the metal lacks some of the beneficial biological properties of natural tissues such as bones and natural teeth. The research conducted with mussels will pave the way for implants that can be more biologically beneficial.
The work began from earlier discoveries that mussels can attach to smooth surfaces so effectively thanks to a protein, L-DOPA, which is known to be able to bind very strongly to smooth surfaces such as rocks, ceramics, or metals. The same protein functions in humans as a precursor to dopamine, and is used as a treatment for Parkinson’s disease.
Using a combination of recombinant DNA technology and treatment with tyrosinase, scientists were able to create a hybrid protein that contained active parts of both the growth factor and L-DOPA. Tests showed that the proteins were able to fold normally, and further experiments in cell cultures demonstrated that the IGF-1 was still functioning normally. Thanks to the incorporation of the L-DOPA, the team was able to confirm that the proteins bound strongly to the titanium surface, and remained attached even when the metal was washed with phosphate-buffered saline, a water-based solution.