Effect of Decorating Titanium with Different Self-Assembled Monolayers on the Electrodeposition of Calcium Phosphate

Abstract

Calcium phosphate (CaP) ceramics are used in orthopedics and dentistry due to their excellent osseointegration and biocompatibility. The electrodeposition of CaP on titanium alloy covered with self-assembled monolayers (SAMs) was studied with respect to the influence of chain length, end-group charge, and anchoring group. SAMs with end-groups similar to the functional groups on the side chains of collagen were selected. This study is divided to three parts: (1) studying the effects of SAMs on the titanium substrate, (2) studying the process of nucleation and growth of the CaP on specific SAMs, and (3) characterizing the CaP coatings using various surface analytical techniques. It was concluded that the nucleation and growth behavior of CaP changed in the presence of the SAMs. Different surface energies and crystallographic phases were associated with this change. Although the nucleation remained progressive, the growth changed from three-dimensional on bare surfaces to two-dimensional on SAMs-covered surfaces. Moreover, the deposition kinetics was slower on SAMs-covered surfaces, with phases containing a higher Ca/P ratio. Examination of the coating revealed that different SAMs lead to different surface morphologies of the coating while maintaining its degree of crystallinity. Yet, the phase content changes from hydroxyapatite and octacalcium phosphate (HAp + OCP) on the bare electrode to OCP only on the SAMs-covered electrode. These changes may have a substantial effect on the in vivo behavior by changing the coating's solubility and surface morphology, thus affecting cell adhesion, proliferation, and differentiation processes.

Corrosion of Metallic Biomaterials: A Review

“…This oxide layer, typically several nanometres thick, is thermodynamically stable and repairs itself rapidly as long as there is low concentration (several ppm) of oxygen or water in the environment. However, because osseointegration of titanium implants takes a long time (typically three to six months), they are often coated with hydroxyapatite (HAp) and other calcium phosphates [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,23,27,28,29,30,31].…”

“…HAp and other CaP coatings provide enhanced osseointegration and fixation of orthopedic and dental implants [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32]. In spite of the porous structure of many of these bioceramic coatings, it was reported that the corrosion resistance of CP-Ti could be improved by electrodepositing it with HAp, as long as the deposition conditions did not result in a too porous coating [12].…”

Biological responses to physicochemical properties of biomaterial surface

“…437 They used XPS and FTIR to confirm that the coating layer was connected to the titanium surface through intermolecular hydrogen bonds. 437 Moreover, Metoki et al 438 studied the calcium phosphate electrodeposition on a titanium alloy covered with SAMs regarding the chain length, end-group charge, and anchoring group. 438 They used ToF-SIMS to confirm that calcium-rich phases were formed primarily in the presence of SAMs.…”

Development and Characterization of Biomimetic Carbonated Calcium-Deficient Hydroxyapatite Deposited on Carbon Fiber Scaffold

“…Among these, the electrochemical technique is particularly attractive for efficiently coating highly irregular materials at ambient temperatures and has been already applied for metal substrates or porous carbon composites [1][2][3][10][11][12][13]. Additionally, the thickness of the coating and its chemical composition can be well controlled by setting adequate…”