Mechanical and biological properties of electrodeposited calcium phosphate coatings

Abstract

Calcium phosphate (CaeP) coatings were electrochemically deposited on titanium substrates. By increasing the electrodeposition time (from 1 to 30 min), the coating thickness increases but also the surface morphology of the CaeP coatings is greatly affected going from smooth to plate-like, featuring elongated plates, ribbon-like and finally sharp needle structures. Micro-stretch tests reveal that, regardless of the coating morphology and thickness, the electrodeposited CaeP coatings have strong adhesion with the titanium substrates and their failure mode is cohesive failure. The effects of different morphologies on cellular behavior such as adhesion, viability, proliferation, and osteogenic gene expression were studied. The surface morphology of CaeP coatings has a remarkable effect on cell attachment, proliferation, and viability. A smooth surface results in better adhesion of the cells, whereas the presence of sharp needles and ribbons on rough surfaces restricts cell adhesion and consequently cell proliferation and viability. The improved cell adhesion and viability on the smoother surface can be attributed to the higher contact area between the cell and the coating, while the needle-like morphology inflicts damage to the cells by physically disrupting the cell wall. There is no significant difference in the level of osteoblast gene expression when osteosarcoma cells are cultured on coatings with different morphologies. Our study provides crucial insights into the optimum electrodeposition procedures for CaeP coating formation leading to both good cell-material interaction and sufficient mechanical properties. This can be achieved with relatively thin coatings produced by short electrodeposition times.

In-Situ Synthesis and Characterization of Chitosan/Hydroxyapatite Nanocomposite Coatings to Improve the Bioactive Properties of Ti6Al4V Substrates

“…The smooth and homogeneous surface coatings clearly induced better cell adhesion, viability, and proliferation than rough surfaces. This behavior may be attributed to the larger contact surface area between the cells and the coating [ 20 , 65 ]. Kamitakahara et al [ 66 ] reported that the wide contact surface area is an important factor for cell proliferation and cells could proliferate easily.…”

“…CS/HA-based biomaterials have been extensively applied for bone substitutes, tissue engineering scaffolds and bone cement [ 14 , 15 , 16 ]. Different approaches have been established to make a ceramic or polymeric based coatings on the surface of metals or alloys [ 17 , 18 , 19 , 20 ]. It was reported that Ti6Al4V substrate was modified by a chitosan film to promote the nucleation of HA/Ag composite coatings deposited by the thermal substrate method [ 21 ].…”

“…In the case of mechanical properties, the chitosan may change the elastic modulus, thus reducing the discrepancy between the implant surface and alveolar bone and decreasing the areas of stress concentration [ 36 ]. The good adhesion strength between the coating and the Ti substrate provides the successful implantation and long-term stability of the coated implant as a considerable characteristic to access the mechanical integrity of the coating system [ 20 ]. For instance, Wang et al [ 37 ] developed a CS/HA composite coating with different concentrations of CS on Ti implants and revealed a significant promotion of the interface bonding strength due to the interactions between HA, CS, and substrate.…”

Electrochemical Impedance Spectroscopy Investigation on the Corrosive Behaviour of Waterborne Silicate Micaceous Iron Oxide Coatings in Seawater

“…On the contrary, the inorganic binders without the VOC are completely environmentally friendly and have become a hot spot for coating research. They mainly include phosphate [18,19], silica sol [20,21] and silicate coatings [22,23]. Silica sol paints form a film by polymerization of silanol group but cohesion is larger during polycondensation, which is likely to cause the coatings to crack or even cause large-areas to fall off.…”

The Influence of Glass Flake and Micaceous Iron Oxide on Electrochemical Corrosion Performance of Waterborne Silicate Coatings in 3.5% NaCl Solution

“…Waterborne inorganic paints are promising substitutes. Waterborne inorganic anticorrosion paints mainly include silicate [11,12], silica sol [13,14], and phosphate paints [15,16]. Silicate and silica sol improve adhesion between metal and coating [17].…”