Electrochemically Deposited Calcium Phosphate Coating on Titanium Alloy Substrates

2005 ◽  
Vol 284-286 ◽  
pp. 247-250 ◽  
Author(s):  
John P. LeGeros ◽  
Shu Jie Lin ◽  
Dindo Q. Mijares ◽  
Fred Dimaano ◽  
Racquel Z. LeGeros
Keyword(s):  
Calcium Phosphate ◽  
Electric Fields ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Calcium Phosphate Coating ◽  
Pulse Time ◽  
Uniform Coating ◽  
Spray Method ◽  
Electrochemically Deposited ◽  
Plasma Sprayed

Plasma-sprayed HA coating combines the strength of the metal and the bioactivity of the HA. However, this method has several disadvantages. Alternatives to the plasma-spray method such as electrochemical deposition (ECD) and biomimetic or precipitation methods are being explored. The purpose of this study was to develop an ECD method for coating Ti alloy substrate with different calcium phosphates (octacalcium phosphate, calcium deficient apatite, carbonatesubstituted apatite, fluoride-substituted apatite). Pairs of Ti6Al4V plates that have been mechanically polished, ultrasonically cleaned, acid etched, rinsed and dried were used as anodes and cathodes. ECD was carried out using programmed pulse time electric fields. Results showed that uniform coating with only the desired calcium phosphate can be obtained using metastable calcium phosphate solutions at different pH and temperature conditions and different electrolyte concentrations. Coating thickness varied with the duration of coating deposition. Crystal size varied with other ECD conditions (e.g., pulse time, current density). This method can be used to obtain uniform coating of the desired calcium phosphate composition at low temperatures (25 to 80oC) on substrates of any type of geometry.

In Situ Characterization of Degradation Behavior of Plasma-Sprayed Coatings on Orthopedic and Dental Implants

2006 ◽  
Vol 49 ◽  
pp. 203-211 ◽  
Author(s):  
Racquel Z. LeGeros ◽  
John P. LeGeros
Keyword(s):  
Calcium Phosphate ◽  
Dental Implants ◽  
Calcium Phosphates ◽  
Interfacial Strength ◽  
Precipitation Method ◽  
Calcium Phosphate Coating ◽  
Implant Surface ◽  
Ha Coating ◽  
Plasma Sprayed

Plasma-sprayed ‘HA’ coatings on commercial orthopedic and dental implants were developed to combine the strength of the metal (Ti or Ti alloy) and the bioactivity of the hydroxyapatite (HA). Several studies have shown that ‘HA’-coated implants provided greater amount of bone attachment, higher bone-implant interfacial strength and accelerated skeletal attachment. However, some reports on implant failures have been attributed to coating delamination and coating early resorption of the plasma sprayed ‘HA’ coating. This paper reviews studies on characterization and degradation of plasma-sprayed ‘HA’ coatings on orthopedic and dental implants and offers alternatives to plasma-spray method of providing calcium phosphate coating. X-ray diffraction analyses showed that plasma-sprayed HA coating consists principally of HA and amorphous calcium phosphate (ACP) with minor amounts of other resorbable calcium phosphates (α- or β-tricalcium phosphates, tetracalcium phosphate), sometimes calcium oxide. The HA/ACP ratios were found to range from 20HA/80ACP to 70HA/30ACP in coated implants from different manufacturers. In vitro initial dissolution rates in acidic buffer (pH 6, 37oC) increased with decreasing HA/ACP ratios in the coating because of the preferential dissolution of the ACP phase. These results suggest that coating with very low HA/ACP ratio may result in the premature resorption of the coating before the bone can attach to the implant thus causing loosening and eventual failure of the implant. Alternatives to plasma-sprayed ‘HA’ are implant surface modifications and low temperature calcium phosphate coatings using electrochemical deposition method or precipitation method.

scholarly journals Mineralization of Titanium Surfaces: Biomimetic Implants

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2879
Author(s):  
Javier Gil ◽  
Jose Maria Manero ◽  
Elisa Ruperez ◽  
Eugenio Velasco-Ortega ◽  
Alvaro Jiménez-Guerra ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Dental Implants ◽  
Early Stage ◽  
Calcium Phosphates ◽  
Biological Fixation ◽  
Biomimetic Surfaces ◽  
Titanium Surfaces ◽  
Deposition Processes ◽  
Fast Dissolution ◽  
Plasma Sprayed

The surface modification by the formation of apatitic compounds, such as hydroxyapatite, improves biological fixation implants at an early stage after implantation. The structure, which is identical to mineral content of human bone, has the potential to be osteoinductive and/or osteoconductive materials. These calcium phosphates provoke the action of the cell signals that interact with the surface after implantation in order to quickly regenerate bone in contact with dental implants with mineral coating. A new generation of calcium phosphate coatings applied on the titanium surfaces of dental implants using laser, plasma-sprayed, laser-ablation, or electrochemical deposition processes produces that response. However, these modifications produce failures and bad responses in long-term behavior. Calcium phosphates films result in heterogeneous degradation due to the lack of crystallinity of the phosphates with a fast dissolution; conversely, the film presents cracks, which produce fractures in the coating. New thermochemical treatments have been developed to obtain biomimetic surfaces with calcium phosphate compounds that overcome the aforementioned problems. Among them, the chemical modification using biomineralization treatments has been extended to other materials, including composites, bioceramics, biopolymers, peptides, organic molecules, and other metallic materials, showing the potential for growing a calcium phosphate layer under biomimetic conditions.

PRECIPITATION CONTROL AND MECHANICAL PROPERTY OF CALCIUM PHOSPHATE–COATED AZ31B ALLOY FOR BIOMEDICAL APPLICATION

2011 ◽  
Vol 23 (03) ◽  
pp. 193-203 ◽  
Author(s):  
Qiang Wang ◽  
Lili Tan ◽  
Qiang Zhang ◽  
Jianhong Qiu ◽  
Ke Yang
Keyword(s):  
Magnesium Alloy ◽  
Calcium Phosphate ◽  
Electrochemical Impedance ◽  
Biomedical Application ◽  
Early Stage ◽  
Calcium Phosphates ◽  
Chemical Deposition ◽  
Biological Properties ◽  
Calcium Phosphate Coating ◽  
Az31b Alloy

Surface modification is believed to be an effective way to control the biodegradation rate of magnesium alloys and improve their biological properties. In the present work, a calcium phosphate (Ca-P) coating was prepared on the AZ31B magnesium alloy by a chemical deposition method to integrate the mechanical advantages of the magnesium substrate and the good bioactivity of the ceramic coating. It was shown that the coating was mainly composed of magnesium and calcium phosphates. Scanning electron microscope coupled with the energy dispersive spectrum analyses showed that rough and crystallined Ca-P coatings with different Ca/P ratios and thickness were formed on the alloy by variation of deposition time. The corrosion resistance of AZ31B alloy was significantly improved by the Ca-P coating. Electrochemical impedance spectroscopy test was used to illustrate the reaction process of Ca-P coating on the alloy. Upon the above results, Ca-P formation mechanism on the AZ31B alloy was proposed. The heterogeneous nucleation and growth of the calcium phosphate coating may be catalyzed by the anodic dissolution of the magnesium alloy substrate in the early stage of deposition, and the deposition coating is mainly composed of the magnesium phosphate. Then calcium phosphate deposition on the alloy becomes dominant with the increase of time. Tensile test in simulated body environment results showed that the time of fracture and ultimate tensile strength for the coated AZ31B Mg alloy were higher than those of the uncoated, which is beneficial in supporting fractured bone for a longer time.

Analysis of the Interface Between Plasma-Sprayed Calcium Phosphate Coating and Ti-6Al-4V

1996 ◽  
Vol 458 ◽  
Author(s):  
Eunsung Park ◽  
David T. Hoelzer ◽  
Robert A. Condrate
Keyword(s):  
Calcium Phosphate ◽  
Bond Strength ◽  
Interfacial Area ◽  
Healing Time ◽  
Physiological Solution ◽  
Calcium Phosphate Coating ◽  
Phosphate Coating ◽  
Interfacial Bond Strength ◽  
Ion Release ◽  
Plasma Sprayed

ABSTRACTPlasma sprayed calcium phosphate coatings on Ti(alloy) have been considered advantageous over the uncoated Ti as dental implants or orthopedic prostheses due to their abilities to decrease healing time, attach firmer to the bone, and inhibit ion release from the Ti substrate. However, the coating was found not to adhere well to the Ti substrate, presumably because there is no or little chemical bonding between the calcium phosphate coating and the Ti substrate. The interfacial bond strength relies almost entirely on the mechanical locking of calcium phosphate splats onto the roughened Ti surface. In this study, the interfacial area between the calcium phosphate coating and the Ti-6A1–4V substrate was characterized using SEM and TEM. The results revealed the presence of amorphous calcium phosphate layer at the interface, which is believed to be responsible for the low bond strength. Also small particles were observed which were embedded in the amorphous phase near the interface. The presence of the amorphous phases is very important since they are more easily attacked by the physiological solution than crystalline phases are.

Corrosion Protection of Nano-biphasic Calcium Phosphate Coating on Titanium Substrate

2020 ◽  
Vol 16 (5) ◽  
pp. 779-792
Author(s):  
Ahlam M. Fathi ◽  
Howida S. Mandour ◽  
Hanaa K. Abd El-Hamid
Keyword(s):  
Calcium Phosphate ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Biphasic Calcium Phosphate ◽  
Titanium Surface ◽  
Electrochemical Impedance ◽  
Calcium Phosphates ◽  
Diffusion Method ◽  
Calcium Phosphate Coating ◽  
Chemical Compositions

Background: Increasing the bioactivity of metallic implants is necessary for biomaterial applications where hydroxyapatite (HA) is used as a surface coating. In industry, HA is currently coated by plasma spraying, but this technique has a high cost and produces coating with short-term stability. Objectives: In the present study, electrophoretic deposition (EPD) was used to deposit nano-biphasic calcium phosphate compound (β-tri-calcium phosphate (β-TCP) /hydroxyapatite (HA)) bio-ceramics on the titanium surface. The microstructural, chemical compositions and bioactivity of the β- TCP/HA coatings were studied in a simulated body fluid solution (SBF). Methods: Scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) were used. Additionally, the antibacterial effect was studied by the agar diffusion method. The corrosion behavior of the β-TCP/HA coating on titanium surface (Ti) in the SBF solution at 37oC was investigated by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests. Results: The Ti surface modification increased its biocompatibility and corrosion resistance in the simulated body fluid. The antibacterial inhibition activity of the β-TCP/HA bio-ceramic was enhanced by electroless silver deposition. The enhanced properties could be attributed to the use of nano-sized biphasic calcium phosphates in a low-temperature EPD process. Conclusions: The β-TCP/HA and β-TCP/HA/Ag coatings well protect Ti from the corrosion in SBF and endow Ti with biocompatibility. The β-4-TCP/HA/Ag/Ti substrate shows good antibacterial activity.

Characterization of Calcium Phosphate with an Anodic TiO2 Nanotube Layer on Titanium Screw for Biomedical Application

2014 ◽  
Vol 852 ◽  
pp. 251-255
Author(s):  
Ya Jing Yan ◽  
Yong Huang ◽  
Qiong Qiong Ding ◽  
Xiao Feng Pang
Keyword(s):  
Calcium Phosphate ◽  
Biomedical Application ◽  
Calcium Phosphates ◽  
Alkaline Treatment ◽  
Calcium Phosphate Coating ◽  
X Ray Diffraction ◽  
Titanium Screw ◽  
Phosphate Coatings ◽  
Titanium Screws ◽  
Calcium Phosphate Coatings

The present paper reports a novel solution to develop a calcium phosphates (CaPs) coating with an anodic nanotubular TiO2layer on titanium screw by electrochemical disposition (ECD). The elemental composition of coatings was examined by energy dispersive spectroscopy (EDS), the surface mopholoy was characterized with scanning electron microscopy (SEM), and the functional groups and crystalline phase were analyzed using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Furthermore, the bioactivity was tested by immersion in simulated body fluid (SBF) for 7 days. The results showed that a nanotubular TiO2layer was established which has about 100 mm diameter and the calcium phosphate coatings have higher bioactivity and porosity compared with uncoated titanium screws, which make the coating more conductive to cell adhesion. Using alkaline treatment, the calcium phosphate coating could transform into hydroxyapatite (HAp), making the coating closer to the biological complement. This provides a valuable tool for biomedical applications.

scholarly journals Phase transformation of calcium phosphates in the presence of glutamic acid

2011 ◽  
Vol 89 (7) ◽  
pp. 885-891 ◽  
Author(s):  
Tim W. T. Tsai ◽  
Wei-Ya Chen ◽  
Yao-Hung Tseng ◽  
Jerry C. C. Chan
Keyword(s):  
Phase Transformation ◽  
Calcium Phosphate ◽  
Glutamic Acid ◽  
Crystal Surface ◽  
Calcium Phosphates ◽  
Water Layer ◽  
Octacalcium Phosphate ◽  
Growth Direction ◽  
Transformation Kinetics ◽  
Transformation Pathway

This work describes a phase-transformation pathway of calcium phosphate in the presence of glutamic acid. The route follows the order starting from amorphous calcium phosphate and brushite, then octacalcium phosphate (OCP), and finally hydroxyapatite (HAp). The preferred growth direction of the intermediate OCP and the final HAp phases lies along the c axis. On the basis of our scanning electron microscopy, X-ray powder diffraction, and 31P solid-state NMR data, we suggest that the transformation is via the dissolution–reprecipitation process, which is facilitated in the presence of glutamic acid. The effect on the transformation kinetics is rationalized by the disruption of the water layer bound on the crystal surface.

Growth of Calcium Phosphate Coating on Ti-7.5Mo Alloy after Anodic Oxidation

2013 ◽  
Vol 334-335 ◽  
pp. 297-302 ◽  
Author(s):  
A.L.A. Escada ◽  
João Paulo Barros Machado ◽  
Roberto Zenhei Nakazato ◽  
Ana Paula Rosifini Alves Claro
Keyword(s):  
Calcium Phosphate ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Calcium Phosphates ◽  
Sodium Titanate ◽  
Ammonium Fluoride ◽  
Biological Properties ◽  
Calcium Phosphate Coating ◽  
Phosphate Coating

Titanium and its alloys are widely used as biomaterials due to their mechanical, chemical and biological properties. To enhance the biocompatibility of titanium alloys, various surface treatments have been proposed. In particular, the formation of titanium oxide nanotubes layers has been extensively examined. Among the various materials for implants, calcium phosphates and hydroxyapatite are widely used clinically. In this work, titanium nanotubes were fabricated on the surface of Ti-7.5Mo alloy by anodization. The samples were anodized for 20 V in an electrolyte containing glycerol in combination with ammonium fluoride (NH4F, 0.25%), and the anodization time was 24 h. After being anodized, specimens were heat treated at 450 °C and 600°C for 1 h to crystallize the amorphous TiO2 nanotubes and then treated with NaOH solution to make them bioactive, to induce growth of calcium phosphate in a simulated body fluid. Surface morphology and coating chemistry were obtained respectively using, field-emission scanning electron microscopy (FEG-SEM), AFM and X-ray diffraction (XRD). It was shown that the presence of titanium nanotubes induces the growth of a sodium titanate nanolayer. During the subsequent in-vitro immersion in a simulated body fluid, the sodium titanate nanolayer induced the nucleation and growth of nanodimensioned calcium phosphate. It was possible to observe the formation of TiO2 nanotubes on the surface of Ti-7.5Mo. Calcium phosphate coating was greater in the samples with larger nanotube diameter. These findings represent a simple surface treatment for Ti-7.5Mo alloy that has high potential for biomedical applications.

Effects of citrate and NaCl on size, morphology, crystallinity and microstructure of calcium phosphates obtained from aqueous solutions at acidic or near-neutral pH

2012 ◽  
Vol 79 (2) ◽  
pp. 238-248 ◽  
Author(s):  
Omar Mekmene ◽  
Thierry Rouillon ◽  
Sophie Quillard ◽  
Paul Pilet ◽  
Jean-Michel Bouler ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Inhibitory Effect ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Phosphate Dihydrate ◽  
Constant Ph ◽  
Starting Solutions ◽  
Calcium Phosphate Precipitation

Precipitation of calcium phosphates occurs in dairy products and depending on pH and ionic environment, several salts with different crystallinity can form. The present study aimed to investigate the effects of NaCl and citrate on the characteristics of precipitates obtained from model solutions of calcium phosphate at pH 6·70 maintained constant or left to drift. The ion speciation calculations showed that all the starting solutions were supersaturated with respect to dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and hydroxyapatite (HAP) in the order HAP>OCP>DCPD. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses of the precipitates showed that DCPD was formed at drifting pH (acidic final pH) whereas poor crystallised calcium deficient apatite was mainly formed at constant pH (6·70). Laser light scattering measurements and electron microscopy observations showed that citrate had a pronounced inhibitory effect on the crystallisation of calcium phosphates both at drifting and constant pH. This resulted in the decrease of the particle sizes and the modification of the morphology and the microstructure of the precipitates. The inhibitory effect of citrate mainly acted by the adsorption of the citrate molecules onto the surfaces of newly formed nuclei of calcium phosphate, thereby changing the morphology of the growing particles. These findings are relevant for the understanding of calcium phosphate precipitation from dairy byproducts that contain large amounts of NaCl and citrate.

Development of Bisphosphonate-Calcium Phosphate Composites and Drug Release Characteristic

2012 ◽  
Vol 1418 ◽  
Author(s):  
Hidekuni Kameda ◽  
Tomohiko Yoshioka ◽  
Toshiyuki Ikoma ◽  
Junzo Tanaka
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Drug Carrier ◽  
Phosphate Buffer Solution ◽  
Octacalcium Phosphate ◽  
Acetate Buffer Solution ◽  
Unit Weight ◽  
Unit Surface Area ◽  
Acetate Solution ◽  
Buffer Solution

ABSTRACTBisphosphonate (Bp) was adsorbed on the surface of crystalline calcium phosphates (CP); hydroxyapatite (HAp), octacalcium phosphate (OCP) and Dicalcium phosphate dehydrate (DCPD). The amount of Bp adsorbed was the largest for DCPD per unit surface area, while the amount was the largest for HAp per unit weight. The composites of Bp and amorphous calcium phosphate (ACP) were synthesized by titrating calcium acetate solution into phosphate buffer solution containing Bp. The amount of Bp doped in the composites was 366 μg / mg and was approximately 7 times larger than those of Bp adsorbed on the crystalline Calcium phosphates. TG-DTA measurements of a Bp-calcium and the composite indicated exothermic peaks due to Bp combustion, of which temperature were shifted to higher temperature for the composite. Bp in the composites was gradually released into phosphate buffered saline, while Bp was rapidly released into acetate buffer solution accompanied with the dissolution of ACP. This result suggests that the composite of Bp and ACP has potential for a drug-carrier releasing Bp in response to the condition of osteoclastic bone resorption.

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