Electrophoretic deposition of chitosan/gelatin/hydroxyapatite nanocomposite coatings on 316 L stainless steel for biomedical applications

In addition to the basic and main parts of hospital equipment, 316 L stainless steel is widely utilized in futures such as nails and screws, wires and medical bone clips, dental implants, heart springs (stents), needles, surgical scissors, etc. In the present study, the electrophoretic deposition of a composite based on chitosan (CS), gelatin, nano and microparticles of hydroxyapatite on a 316 L stainless steel substrate was investigated. Hydroxyapatite particles are added to it due to the ossification abilities of steel and due to an enhanced adhesion and bone production, CS and biocompatible gelatin polymer particles were also added to hydroxyapatite. These particles were mixed in an ethanol/deionized water/acetic acid solution to create a suspension for the electrophoretic procedure. A mixture of 5 g l^-1of hydroxyapatite, 0.5 g l^-1of CS, and 1 g l^-1were present in the suspension. The best coating time was 1200s, and the best voltage was 30 V. The high density of the hydroxyapatite particles in the CS/gelatin polymer matrix was seen in scanning electron microscopy pictures. Additionally, the outcomes of the immersing samples in the simulated body fluid were evaluated, and the results revealed that, after 14 d, hydroxyapatite nanoparticles grew more rapidly than microparticles. The presence of CS, gelatin, and hydroxyapatite in the coating was verified by energy dispersive x-ray spectroscopy, Fourier transform infrared spectroscopy, and x-ray diffraction. Electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization in Phosphate-buffered saline were used to assess the corrosion results. In comparison to the bare sample, the corrosion resistance of the coated sample increased from 1.22 × 10⁵to 7.17 × 10⁵Ω.cm²under best circumstances, according to EIS results. Additionally, in the polarization test, the corrosion potential increased from -225.24 to -157.01 mV (vs. SCE) and the corrosion current dropped from 2.159 to 1.201 µA cm^-2.