A study on retention of MWCNT in robocasted MWCNT-HAP scaffold structures using vacuum sintering technique and their characteristics

Abstract

Bioceramic scaffolds are being widely employed in bone tissue engineering applications for their ability to interact with host tissues without inducing any toxicity. Additionally, bioceramics possess good biocompatibility, osteointegration, osteoinduction, and biodegradation characteristics. Hydroxyapatite (HAP) is one such bioceramic known to exhibit closeness to natural bone in terms of chemical composition. The present reports additive manufacturing of HAP and Multiwalled carbon nanotubes (MWCNTs) reinforced HAP scaffold structures for bone tissue engineering applications using the Robocasting technique. Carboxymethyl Cellulose (CMC) was employed as the polymeric binder in this study to prepare the highly viscous HAP and CNT-HAP slurry ideal for robocasting of the scaffold structures. Different percentages of MWCNT (0.5, 1 and 2 wt%) incorporated into the developed CNT-HAP scaffold structures and were vacuum sintered at 1000 °C for 15 min. Vacuum sintering was found to effectively prevent oxidation of MWCNT which is subjected to decomposition at temperatures above 400 or 500 °C in Oxygen atmosphere as per literature. Further, the retention of MWCNTs in the developed CNT-HAP structures post sintering was confirmed using FESEM imaging. The mechanical characterizations revealed that 0.5CNT-HAP structures exhibited highest compression strength (3.36 ± 0.67 MPa) in comparison to 1CNT-HAP and 2CNT-HAP structures. Also, the in vitro biological characterizations demonstrated that the developed CNT-HAP scaffold structures were cytocompatible and remained stable for about 35 days at 37 °C.