Synthesis and characterization of hydroxyapatite/carboxylic acid functionalized MWCNTS composites and its triple layer coatings for biomedical applications

Abstract

IntroductionAchievement of bioactive coatings on metallic implant surface with higher adhesive strength and corrosive resistance was one of the main challenges for the current biomaterial researchers. Hydroxyapatite was one of the promising bioactive ceramic which can be applied as a coating on the metallic substrate due to its similarity with the human bone. MethodsThe work describes the in-situ preparation of HAP/f-MWCNTs composite by sol-gel method. MWCNTs were functionalized by acid treatment. HAP composites have been prepared by varying the molar percentage of f-MWCNTs from 1% to 5%. The prepared composites with various concentrations of f-MWCNTs were characterized by FT-IR and XRD for its functional group analysis and phase purity. The morphology of the prepared powder was analyzed using SEM and TEM. In-vitro corrosive behavior on SBF was studied for the coating prepared HAP composite sol on 316L SS. The triple layer composite coating was obtained at the spin speed of 3000 rpm/min and subjected to sintering at 500 °C/2 h. ResultsX-ray diffraction results confirmed the formation of pure HAP up to the addition of 3% of f-MWCNTs without any secondary phases. The average crystallite size of the prepared particles was decreased from 40 ± 2.1 to 17 ± 2.5 nm with the addition f-MWCNTs. The morphological studies confirm the incorporation of f-MWCNTs in HAP matrix. The prepared HAP/f-MWCNTs composite efficiently inhibits the growth of the pathogens such as S. Aureus and E.coli. Improved hardness was observed with reinforcement of f-MWCNTs into the hydroxyapatite matrix. Electrochemical studies confirm the HAP/f-MWCNTs composites having increased corrosive resistance properties. The bonding strength of the composite coatings showed improved adhesion to the 316L surface. ConclusionIn this work we have fabricated sol-gel derived anti-microbial composite coating on the 316L substrate by means of spin coating at optimized conditions with higher adhesive strength and improved corrosion resistance.