A new titanium biofunctionalized interface based on poly(pyrrole-3-acetic acid) coating: proliferation of osteoblast-like cells and future perspectives.

In recent years, many procedures based on surface modification have been suggested to improve the biocompatibility and biofunctionality of orthopedic titanium-based implants. In this contest, the development of a new titanium-based biomaterial that could be covalently modified with biologically active molecules (i.e., RGD-peptides, growth factors, etc.) able to improve osteoblasts response was investigated. The strategy followed was based on a preliminary coating of the implant material by an adherent thin polymer film to which bioactive molecules could be grafted exploiting the polymer surface chemical reactivity. In this work, we focused our attention on pyrrole-3-acetic acid (Py-3-acetic), a pyrrole with carboxylic acid substituent, whose electrosynthesis and characterization on titanium substrates were already accomplished and whose potentialities in the design of new biocompatible surfaces are well evident. As first step, the biocompatibility of the electrochemically grown PPy-3-acetic films was investigated performing in vitro tests (adhesion and proliferation) with mouse bone marrow cells. Successively, the availability and reactivity of surface carboxylic groups were tested through the grafting of an aminoacidic residue to PPy-3-acetic films.