title: Electrophoretic deposition of bioactive silica-calcium phosphate nanocomposite on Ti-6Al-4V orthopedic implant.
abstract: Bioactive silica-calcium phosphate nanocomposite (SCPC) has been coated on Ti-6Al-4V implant employing an electrophoretic deposition (EPD) technique. The effects of composition and pH of the suspending medium on the zeta potential of three different SCPC formulations; SCPC25, SCPC50 and SCPC75 were analyzed. The average zeta potential of SCPC50 in pure ethanol was more negative than that of SCPC25 or SCPC75; however, the difference was not statistically significant. Discs of Ti-6Al-4V were passivated, coated with SCPC50 (200 nm-10 μm) and thermally treated at 600-800°C to produce a coating thickness in the range of 43.1 ± 5.7 to 30.1 ± 4.6 μm. After treatment at 600, 700, and 800°C, the adhesion strength at the SCPC50/Ti-6Al-4V interface was 42.6 ± 3.6, 44.7 ± 8.7, and 47.2 ± 4.3 MPa, respectively. SEM-EDX analyses of SCPC50-coated Ti-6Al-4V preimmersed in PBS for 7 days showed the formation of a Ca-deficient hydroxyapatite surface layer. ICP-OES analyses of the immersing solution (n = 6) showed an increase in the ionic concentration of Si from 3.3 ± 0.9 to 5.0 ± 1.2 ppm between days 1 and 4; after which no significant change in the Si concentration was measured. Bone marrow mesenchymal stem cells attached to the SCPC50-coated implants expressed significantly higher (p < 0.05) alkaline phosphatase activity (82.4 ± 25.6 nmoles p-NP/mg protein/min) than that expressed by cells attached to HA-coated or uncoated implants. Results of the study suggest that bioactive SCPC50 can efficiently be coated on Ti-6Al-4V using EPD. The SCPC50 coating has the potential to enhance bone integration with the orthopedic implant.
authors.affiliation: Department of Mechanical Engineering and Engineering Science, The University of North Carolina at Charlotte, Charlotte, North Carolina, USA.
authors.lastname: Aniket
authors.forename: Ahmed
authors.initials: A
authors.lastname: El-Ghannam
mesh_terms: D000268:Adhesiveness; D000497:Alloys; D001672:Biocompatible Materials / Q000737:chemistry; D001854:Bone Marrow Cells / Q000166:cytology; D002130:Calcium Phosphates / Q000737:chemistry*; D002516:Ceramics; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D017886:Durapatite / Q000737:chemistry; D004553:Electric Conductivity; D006801:Humans; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000166:cytology; D009985:Orthopedics / Q000379:methods*; D010316:Particle Size; D019736:Prostheses and Implants; D017640:Silicates / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D017640:Silicates; C499768:silica-calcium phosphate nanocomposite; C031462:titanium alloy (TiAl6V4); D017886:Durapatite; D014025:Titanium