Electrochemical processes of nucleation and growth of hydroxyapatite on titanium supported by real‐time electrochemical atomic force microscopy

Abstract

Recently, interest in electrochemical formation of hydroxyapatite has evolved. In this work, highly crystalline hydroxyapatite is electrodeposited on pure titanium and Ti-6Al-4V alloy. In situ and ex situ imaging, coupled with potentiostatic and potentiodynamic measurements, is conducted by means of electrochemical atomic force microscopy. This allows for a study of the nucleation and growth of hydroxyapatite as well as of its near-atomic structure. Electrodeposition of hydroxyapatite is shown to result from precipitation in solution, following two stages: (1) instantaneous nucleation, two-dimensional growth; (2) progressive nucleation, three-dimensional growth. Although some nucleation occurs already at -842 mV, potentials that are more negative than -1.26 V versus SCE are required for enhanced growth. Mass transport is found to have only secondary effect on the deposition process. The conclusions of this work have implications in optimization of coatings on implants as well as in enhancement of the understanding of bone mineralization in vivo.

Tuning the Initial Electronucleation Mechanism of Palladium on Glassy Carbon Electrode

“…Table 1. The time dependence of the number density of nuclei N (t) formed on a substrate exhibiting equally active nucleation sites N o has been described as [12,26] (…”

Electrochemical Fabrication of Copper-Based Hybrid Microstructures and Mechanism of Formation of Related Hierarchical Structures on Polypyrrole Films

“…The data start departing from both models at about 2t MAX as a result of the changes in the deposition process, such as precipitation from the solution rather than direct nucleation on the film surface or changes of pH and composition of the solution during the deposition. 56 In addition, the progressive nucleation is also evident from Figure 6, where a large number of nucleation sites is found, with each hierarchical structure growing in an independent manner. The structures have different sizes, confirming that the nucleation is progressive, with new sites being established during the electrodeposition period.…”

Electrocatalytic properties of hydroxyapatite thin films electrodeposited on stainless steel substrates

“…A similar evolution was noted by Eliaz and al. 29 who attributed this evolution to the growth of phosphocalcic coating. The rapid decrease of the initial potential can be explained by the double layer charge.…”

“…The increase of potential following this first stage could be ascribed to a onedimensional crystal growth. At the end, the stability of the potential would indicate that the surface of the cathode would be no longer modified 29 . Figure 6 represents three deposit steps: (i) fast decrease during the first seconds corresponding to the electrical charge of the double layer; (ii) increase of potentially linked to the unidimensional growth of coating; (iii) finally, the stabilization of the potential close to 2V, corresponding to the invariance of the electrode surface 9 .…”