Synthesis and assessment of metallic ion migration through a novel calcium carbonate coating for biomedical implants.

Author(s) Bang, L.Thi; Filho, L.C.; Engqvist, H.; Xia, W.; Persson, C.
Journal J Biomed Mater Res B Appl Biomater
Date Published 2020 Feb

Titanium (Ti) implants are commonly regarded as well accepted by the body. However, metal ion release is still a cause for concern. A small decrease in pH, which can be caused by inflammation, may produce a large increase in the corrosion rate of Ti implants. Coating the alloy with a buffer layer could have a significant protective effect. In this study, a calcium carbonate coating was developed on commercially pure Ti and a Ti-6Al-4V alloy through a hydrothermal treatment of previously NaOH-treated surfaces in calcium-citric acid chelate complexes. The results showed that a superstructured calcite coating layer formed on the Ti substrate after treatment at 170°C for 3 hr. The coating was approx. 1 μm thick and covered the substrate surface uniformly. When prolonging the hydrothermal treatment from 5 hr to 24 hr, the rhombohedral structure of calcite was observed in addition to the superstructure of calcite. Dissolution test results showed no significant differences in solution pH between the coated- and un-coated samples. However, the CaCO coating reduced by approx. 2-5 times the Ti and V ion release from the substrate as compared to the uncoated material, at pH 4. CaCO and hydroxyapatite (HA) coatings gave nonsignificant effects at neutral pH although the HA coating showed a trend for better results at the longer time points. The reduction in metal ion release from the substrate and the buffering ability of the CaCO coating encourage further studies on this coating for clinical applications.

DOI 10.1002/jbm.b.34399
ISSN 1552-4981
Citation J Biomed Mater Res Part B Appl Biomater. 2020;108(2):429438.

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