Effect of cell culture media and bones cells on the corrosion behavior of biomedical grade CoCrMo alloy

摘要

Cobalt-Chromiurn-Molybdenum (CoCrMo) alloys are used for biomedical applications due to their biocompatibility, their high mechanical properties and their corrosion resistance in the physiological medium This corrosion resistance is due to the presence of a Cr-rich passive film which prevents direct contact of the metal with body fluids. This phenomenon insures the durability of orthopedic implants. As commonly assumed, the growth, the steady-state and the breakdown of passive state are closely related to the chemical composition of the alloys but also the environmental conditions (pH, ionic salts...). Evaluating the evolution of the passive state with time and predicting it during the lifespan of the prosthesis is of great necessity. For that reason, many studies provides a general overview of the corrosion behavior of CoCrMo alloys in simulated physiological fluids. However, few studies assess the CoCrMo surface reactivity in cell culture media where the biocompatibility tests are generally performed. Even fewer studies compare the results obtained with and without cells activities. From conventional electrochemical technics and electrochemical impedance spectroscopy, the present study addresses the role of the cell culture medium on the surface reactivity of metallic biomaterials by electrochemical measurements, surface analyses and biological tests. Because it was mainly used for osteoblast cells culture, the selected medium was the Roswell Park Memorial Institute (RPMI) supplemented with 10% fetal bovine serum (FBS) and 1% antibiotics. All the experiments were performed in an incubator dedicated to cells culture (37°C- 5% CO_2) and compared to results obtained in aerated conditions. As a first result, the change of electrochemical or physicochemical reactions at the surface of the CoCrMo due to CO_2 atmosphere was established. Afterward, the corrosion behavior of CoCrMo alloy was studied in presence of different osteoblasts cell lines in the same solution. Results highlight the bones cells viability and activity. By comparing the biological response and the electrochemical behavior of CoCrMo, better insights into how complex biological systems evolve with the environment was then discussed.