Direct nanocrystalline hydroxyapatite formation on titanium from ultrasonated electrochemical bath at physiological pH

Abstract An electrochemical method of producing nanocrystalline hydroxyapatite coatings on titanium surface is reported. The bath contained Ca(NO3)2 and NH4H2PO4 in the molar ratio 1.67:1. The electrolyte was maintained at physiological pH and was ultrasonically agitated throughout the time of electrolysis. Coatings were deposited for 30 min at 10 and 15 mA/cm2 and contained mono hydroxyapatite phase whose crystal sizes were lower than 30 nm. These sizes are comparable to the size of the bone hydroxyapatite crystals. Small globules of hydroxyapatite covered the coating surface completely. Fourier transformed infra-red spectroscopy (FT-IR) studies showed that the coatings contained large amounts of hydroxide and phosphate groups to enable the formation of hydroxyapatite. The coatings had a roughness (Ra) of about 0.3 μm and water contact angles of about 49°. Ultrasonic agitation promoted the formation of nanocrystalline structure which will help in better attachment of bone tissues to the implant surface.

[1]  M. Kumar,et al.  Electrodeposition of brushite coatings and their transformation to hydroxyapatite in aqueous solutions. , 1999, Journal of biomedical materials research.

[2]  N. Voelcker,et al.  Thin calcium phosphate coatings on titanium by electrochemical deposition in modified simulated body fluid. , 2006, Journal of biomedical materials research. Part A.

[3]  M. Stölzel,et al.  Electrochemically assisted deposition of thin calcium phosphate coatings at near-physiological pH and temperature. , 2003, Journal of biomedical materials research. Part A.

[4]  M. Y. Abyaneh.  Extracting nucleation rates from current–time transients: Part I: the choice of growth models , 2002 .

[5]  J. Weng,et al.  Characterization of titanium surfaces with calcium and phosphate and osteoblast adhesion. , 2004, Biomaterials.

[6]  I. Rehman,et al.  Preparation and characterization of fluoride-substituted apatites , 1997, Journal of materials science. Materials in medicine.

[7]  S. Spriano,et al.  Surface properties and cell response of low metal ion release Ti-6Al-7Nb alloy after multi-step chemical and thermal treatments. , 2005, Biomaterials.

[8]  Y. Leng,et al.  Calcium phosphate crystal growth under controlled atmosphere in electrochemical deposition , 2005 .

[9]  M. Shirkhanzadeh.  Direct formation of nanophase hydroxyapatite on cathodically polarized electrodes , 1998, Journal of materials science. Materials in medicine.

[10]  Hyoun‐Ee Kim,et al.  Hydroxyapatite coating on titanium substrate with titania buffer layer processed by sol-gel method. , 2004, Biomaterials.

[11]  L L Hench,et al.  Surface-active biomaterials. , 1984, Science.

[12]  T. Webster,et al.  Increased osteoblast adhesion on titanium-coated hydroxylapatite that forms CaTiO3. , 2003, Journal of biomedical materials research. Part A.

[13]  M. Kikuchi,et al.  Synthesis of Bone-Like Hydroxyapatite/Collagen Nano-Composites by Soft-Nanotechnology , 2006 .

[14]  M. Maitz,et al.  Promoted calcium-phosphate precipitation from solution on titanium for improved biocompatibility by ion implantation , 2002 .

[15]  R. Narayanan,et al.  Electrochemical nano-grained calcium phosphate coatings on Ti–6Al–4V for biomaterial applications , 2007 .

[16]  T. Webster,et al.  Increased functions of osteoblasts on nanophase metals , 2007 .

[17]  J. Redepenning,et al.  Characterization of electrolytically prepared brushite and hydroxyapatite coatings on orthopedic alloys. , 1996, Journal of biomedical materials research.

[18]  K Nakanishi,et al.  The role of hydrated silica, titania, and alumina in inducing apatite on implants. , 1994, Journal of biomedical materials research.

[19]  R. Heimann,et al.  Compositional and microstructural changes of engineered plasma-sprayed hydroxyapatite coatings on Ti6Al4V substrates during incubation in protein-free simulated body fluid. , 2000, Journal of biomedical materials research.

[20]  P Ducheyne,et al.  Calcium phosphate ceramic coatings on porous titanium: effect of structure and composition on electrophoretic deposition, vacuum sintering and in vitro dissolution. , 1990, Biomaterials.

[21]  W. Read,et al.  Crystal Growth and Dislocations , 1954 .

[22]  Larry L. Hench,et al.  Bioceramics: From Concept to Clinic , 1991 .

[23]  T. Vijayaraghavan,et al.  Electrodeposition of apatite coating on pure titanium and titanium alloys , 1994 .

[24]  L. Morbidelli,et al.  The effect of hydroxyapatite nanocrystals on microvascular endothelial cell viability and functions. , 2006, Journal of biomedical materials research. Part A.

[25]  Thomas J Webster,et al.  Using hydroxyapatite nanoparticles and decreased crystallinity to promote osteoblast adhesion similar to functionalizing with RGD. , 2006, Biomaterials.

[26]  O. Sbaizero,et al.  Mechanical and chemical consequences of the residual stresses in plasma sprayed hydroxyapatite coatings. , 1997, Biomaterials.

[27]  Noam Eliaz,et al.  Electrochemical processes of nucleation and growth of hydroxyapatite on titanium supported by real-time electrochemical atomic force microscopy. , 2007, Journal of biomedical materials research. Part A.

[28]  S. Yen,et al.  Cathodic reactions of electrolytic hydroxyapatite coating on pure titanium , 2003 .

[29]  S. Yen,et al.  The process of electrochemical deposited hydroxyapatite coatings on biomedical titanium at room temperature , 2002 .

[30]  Sungho Jin,et al.  Titanium oxide nanotubes with controlled morphology for enhanced bone growth , 2006 .

[31]  J. Fernández‐Pradas,et al.  Bone growth on and resorption of calcium phosphate coatings obtained by pulsed laser deposition , 2000 .

[32]  B. Cullity,et al.  Elements of X-ray diffraction , 1957 .