Indian Journal of Science and Technology

Abstract

Hydroxyapatite (HA), as a bone mineral component, has been an attractive bioceramic for the reconstruction of hard tissues. However, its poor mechanical properties, including low fracture toughness and tensile strength, have been a significant challenge to the application of HA for the replacement of load-bearing and/or large bone defects. Hydroxyapatite (HA) composite is reinforced with high purity and well-functionalized Multiwalled Carbon Naotubes (MWCNT>98 wt%) having an average diameter of 15 nm.The cellular response of f-MWCNT, MWCNT-HA composites were examined to model gram positive and gram negative Bacteria B. subtilis, P. aeruginosa and yeast C. albicans. Ca(NO3 )2 .4H2 O and (NH4 )2 HPO4 were used to synthesize HA in situ. MWCNT were functionalized by heating at 1000 C in 3:1 ratio of H2 SO4 and HNO3 for 60 m with stirring and dispersed in Sodium Dodecyl Benzene Sulphonate (SDBS) by sonication. Hydroxy Apatite (HA) particles were produced in MWCNTs solution by adding Ca(NO3 )2 .4H2 O and (NH4 )2 HPO4 under vigorously stirring conditions. The composite were dried and washed in distilled water followed by heat treatment at 2500 C to obtain CNT-HA powder. Using FTIR, FESEM and EDS does physicochemical characterization of the composite material. The interaction of f-MWCNT and MWCNT-HA were tested on Bacillus subtilis, P. aeruginosa and C. albicans. The zone of inhibition and MIC studies were carried out with a concentration range from 62.5 – 1000 µg/ml. The test result shows no zone of inhibition and MIC > 1000 µg/ml on bacteria and yeast. This result provides further evidence that the bio-nano interface can be developed for Carbon Nanotubes reinforced Hydroxyapatite composites for load-bearing bone implants, drug delivery and diagnostic applications. 
Keywords: Hydroxyapatite, MIC, MWCNTs, Nanocomposites