Enhancing the surface characteristics of 316L stainless steel for orthopedic implants: A comprehensive in vivo study of electrophoretic deposition process and surface modification

• N.A. Al-Ali, M.H. Abdulkareem and I.A. Anoon

Department of Production Engineering and Metallurgy, University of Technology, 10066 Al Sina’a Street, Baghdad, Iraq

Abstract: This study aimed to enhance the osseointegration of 316L stainless steel substrate by surface activation through the application of multifunctional composite coatings consisting of biopolymers, bioactive materials, and bioinert substances. The coated implants were compared with uncoated 316L stainless steel screws as control. The electrochemical deposition technique known as Direct Current Electrophoretic Deposition (EPD) was employed to fabricate four composite coating layers on the stainless-steel substrate. Seven local breed rabbits were divided into two groups: the control group, which received uncoated screws, and the coated group, which received screws with composite coatings. Optical microscopy analysis confirmed the presence of homogenous composite layers without any defects. The corrosion resistance of 316L stainless steel improved as the number of coating composite layers was increased. Atomic force microscopy (AFM) was used to assess the surface roughness of the coatings, with average roughness values (R_a) of 1.32 nm and average diameter of the composite particles measuring 7.59 nm. Upon contact with simulated body fluid (SBF), the composite coatings facilitated the partial replacement of bioactive glass with silica particles, creating a topography conducive to hydroxyapatite development. Radiographic examination conducted after 6 weeks of implantation revealed secure embedding of both uncoated and coated screws in the tibial bone. Moreover, histopathological evaluation demonstrated superior osteoblast proliferation and mature bone formation in the coated screw group compared to the uncoated screw group, indicating the biocompatibility and effectiveness of the composite coatings in promoting bone growth. In conclusion, the application of multifunctional composite coatings using EPD significantly improves the osseointegration of 316L stainless steel implants. The findings suggest that these coatings have the potential to enhance the long-term success of orthopedic implants by facilitating bone formation and ensuring secure fixation within the bone.

Keywords: electrophoretic deposition (EPD), biopolymers, bioactive glass (45S5)

Int. J. Corros. Scale Inhib., 2023, 12, no. 4, 1992-2023
doi: 10.17675/2305-6894-2023-12-4-30

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