Mukherjee, Susmita and Kundu, Biswanath and Sen, Swamendu and Chanda, Abhijit (2014) Improved properties of hydroxyapatite-carbon nanotube biocomposite: Mechanical, in vitro bioactivity and biological studies. Ceramics International, 40 (4). pp. 5635-5643. ISSN 0272-8842

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The present work describes a simple shear mixing technique for developing a hydroxyapatite (HAp)-carbon nartotube (CNT) nanocomposite and the effect of reinforcement on the physical, mechanical, in vitro bioactivity and biological properties of HAp. XRD and El lit confirmed that the main phase of the composites is HAp. HRTEM images demonstrated the formation of a two-dimensional nanocomposite structure, whereas FESEM images indicated the formation of nanosized HAp grains featuring sporadically distributed CNT molecules. No major phase changes in HAp were observed with up to 5% added CNT. However, adding more than 1% CNI's caused an increase in internal crystal strain and increased substitution of CO32- for OH- and PO43- groups in pure HAp. The average crystallite size increased from similar to 46 nm to similar to 100 nm with only 0.5% added CNT, remained nearly unaffected up to 2% CNTs thereafter and suddenly decreased at 5% CNTs (similar to 61 nm). The FESEM and HRTEM images clearly showed the attachment of MWCNT chains on HAp grains, which directly affected the samples fracture toughness and flexural strength. Of the samples, 1% showed maximum values of K-1C, whereas 5% showed maximum values of HV and three-point bending flexural strength. The in vitro bioactivity indicated increased apatite formation on the sample surface up to 1% CNTs after 24 weeks. However, adding 2% and 5% CNTs resulted in a manifold increase in apatite formation up to 12 weeks, after which dissolution increased up to 24 weeks, possibly due to increased substitution of CO32- for OH- and PO43- groups. This result is confirmed by the Fl1R studies. For all added CNT contents, all samples exhibited high haemocompatibility. However, there was a compromise between the observed mechanical properties and in vitro bioactivity studied up to 24 weeks, and care must be taken before selecting any final application of the nanocomposites. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Item Type: Article
Subjects: Engineering Materials
Divisions: Bioceramics & Coating
Depositing User: Bidhan Chaudhuri
Date Deposited: 28 Nov 2014 05:40
Last Modified: 28 Nov 2014 05:40

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