Fabrication and Characterization of Ag–Sr-Substituted Hydroxyapatite/Chitosan Coatings Deposited via Electrophoretic Deposition: A Design of Experiment Study

Abstract

In this study, silver–strontium-doped hydroxyapatite (AgSr-HA)/chitosan composite coatings were deposited on a 316L stainless steel (SS) substrate via electrophoretic deposition (EPD). The Taguchi design of experiment (DoE) approach was used to optimize the EPD parameters such as the applied voltage, interelectrode spacing, and deposition time. Furthermore, the concentration of AgSr-HA particles in the suspension was also optimized via the DoE approach. DoE results demonstrated that the “homogeneous” coatings were obtained at the deposition time of 7 min, deposition voltage of 20 V, and at a concentration of 5 g/L AgSr-HA particles in the suspension. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), antibacterial studies, contact angle, and roughness measurements were performed to characterize the optimized coatings. SEM images confirmed the deposition of chitosan/AgSr-HA on the SS substrate. The wettability studies indicated the hydrophilic nature of the chitosan/AgSr-HA composite coatings, which confirmed that the developed coatings are suitable for biomedical applications, e.g., orthopedics. The average surface roughness of the chitosan/AgSr-HA composite coatings was in a suitable range used to attach the bone marrow stromal cells. Chitosan/AgSr-HA composite coatings showed an effective antibacterial effect against Gram-positive and Gram-negative bacteria. Moreover, the coatings developed apatite crystals on their surface upon immersion in simulated body fluid.

Chitosan/gelatin‐based bioactive and antibacterial coatings deposited via electrophoretic deposition

“…Antibacterial results confirmed the strong antibacterial effect toward both Gram‐negative and Gram‐positive bacteria. Similar reports 22,29,44 illustrate the antibacterial effect associated with the chitosan and Ag. It was reported that 0.21 wt% Ag in the coating may lead to toxicity.…”

“…The 45S5 BG (Schott AG™, Germany) with an average particle size of 4 μm and nominal composition of 45 wt% SiO 2− , 24.5 wt% Na 2 O, 24.5 wt% CaO, 6 wt% P 2 O 5 28 was used. The PEEK powder (704 XF, Victrex™) with an average particle size of 10 μm was used to prepare PEEK/BG coatings 13,29,30 . The Ag and Mn‐doped MBGNs (Ag‐Mn MBGNs) were synthesized via modified Stöber method.…”

Ag–Sr doped mesoporous bioactive glass nanoparticles loaded chitosan/gelatin coating for orthopedic implants

“…The concentration of Ag–Sr MBGNs was selected to be in the range of 1–5 g/L because the concentration lower than 1 g/L will not be enough to provide antibacterial effect and bioactivity. The concentrations higher than 5 g/L will cause the sedimentation of the dispersed Ag–Sr MBGNs 33 …”

“…The concentrations higher than 5 g/L will cause the sedimentation of the dispersed Ag-Sr MBGNs. 33 2.5 | EPD of C/G/Ag-Sr MBGNs 316L stainless steel (SS) foil was cut into dimensions of 2.5 cm × 3 cm. Samples were soaked in a mixture of ethanol and acetone and sonicated for 15 minutes followed by drying.…”

“…The positively charged polyelectrolyte complex of C/G encapsulated the Ag-Sr MBGNs particles and then these positively charged C/G/ Ag-Sr MBGNs can be co-deposited at cathode upon the application of the electric field. 32,33 The direct current-EPD (DC-EPD) process was applied in a vertical position at different voltages and deposition times (according to the matrix developed by the Taguchi DoE approach, discussed in Section 2.6). According to Hamaker's model, 35 the deposition yield is linearly dependent on the particle concentration, electrical field, deposition time, and the mobility of the particles/molecules.…”