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Current strategies of bilayer technology have been aimed mainly at the enhancement of bioactivity, mechanical property and corrosion resistance. In the present investigation, the electropolymerization of poly(3,4-ethylenedioxypyrrole-co-3,4-ethylenedioxythiophene) (P(EDOP-co-EDOT)) with various feed ratios of EDOP/EDOT on surgical grade stainless steel (316L SS) and the successive electrodeposition of strontium (Sr(2+)), magnesium (Mg(2+)) and cerium (Ce(3+)) (with 0.05, 0.075 and 0.1 M Ce(3+)) substituted porous hydroxyapatite (M-HA) are successfully combined to produce the bioactive and corrosion resistance P(EDOP-co-EDOT)/M-HA bilayer coatings for orthopedic applications. The existence of as-developed coatings was confirmed by Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), proton nuclear magnetic resonance spectroscopy ((1)H NMR), high resolution scanning electron microscopy (HRSEM), energy dispersive X-ray analysis (EDAX) and atomic force microscopy (AFM). Also, the mechanical and thermal behavior of the bilayer coatings were analyzed. The corrosion resistance of the as-developed coatings and also the influence of copolymer (EDOP:EDOT) feed ratio were studied in Ringer's solution by electrochemical techniques. The as-obtained results are in accord with those obtained from the chemical analysis using inductively coupled plasma atomic emission spectrometry (ICP-AES). In addition, the antibacterial activity, in vitro bioactivity, cell viability and cell adhesion tests were performed to substantiate the biocompatibility of P(EDOP-co-EDOT)/M-HA bilayer coatings. On account of these investigations, it is proved that the as-developed bilayer coatings exhibit superior bioactivity and improved corrosion resistance over 316L SS, which is potential for orthopedic applications.

Novel multifunctional biocomposite materials that mimic the properties of bone are the need of the hour. In view of this, the current work is focused on the fabrication of a snail shells derived europium-substituted hydroxyapatite (Eu-HAP)/poly­(3,4-propylenedioxythiophene) (PProDOT)/Calotropis gigantea fiber (CGF) ternary composite on titanium (Ti) for biomedical applications. The structural, morphological, mechanical, electrochemical, and biological properties of the as-developed coatings on Ti were characterized. The obtained results clearly confirmed the formation and properties of the ternary composite (Eu-HAP/PProDOT/CGF). The presence of CGF, an exceptional reinforcement material, in the ternary composite is proven to improve mechanical and biological properties compared to other coatings (i.e., coating without CGF). Also, electrochemical studies revealed better anticorrosion properties of the composite-coated Ti in a simulated body fluid (SBF) solution. Similarly, the presence of Eu-HAP and PProDOT in the composite is clearly evident from the antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and also by the cell proliferation and cell adhesion by the MTT assay test. Thus, we suggest that the fabricated Eu-HAP/PProDOT/CGF ternary composite with mechanical, corrosion resistance, and biocompatible properties might be an appropriate candidate for biomedical applications.

The current work mainly focuses on the innovative nature of nano-gallium-substituted hydroxyapatite (nGa-HAp)/Pergularia daemia fiber extract (PDFE)/poly­(N-vinylcarbazole) (PVK) biocomposite coating on titanium (Ti) metal in an eco-friendly and low-cost way through electrophoretic deposition for metallic implant applications. Detailed analysis of this nGa-HAp/PDFE/PVK biocomposite coating revealed many encouraging functional properties like structure and uniformity of the coating. Furthermore, gallium and fruit extract of PDFE-incorporated biocomposite enhance the in vitro antimicrobial, cell viability, and bioactivity studies. In addition, the mechanical and anticorrosion tests of the biocomposite material proved improved adhesion, hardness, and corrosion resistance properties, which were found to be attributed to the presence of PDFE and PVK. Also, the swelling and degradation behaviors of the as-developed material were evaluated in simulated body fluids (SBF) solution. The results revealed that the as-developed composite exhibited superior swelling and lower degradation properties, which evidences the stability of composite in the SBF solution. Overall, the results of the present study indicate that these nGa-HAp/PDFE/PVK biocomposite materials with improved mechanical, corrosion resistance, antibacterial, cell viability, and bioactivity properties appear as promising materials for biomedical applications.

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