Cytotoxic effect of an alumina matrix composite with APTS-functionalized carbon nanotubes in Vero cells

Alumina (Al 2 O 3 ) is a hard, highly biocompatible and low friction ceramic material of multiple biomedical applications, but mechanically weak and showing poor flexibility. To circumvent these limitations, it could be complexed as composite materials with carbon nanotubes (CNTs). However, CNTs display cytotoxic effects. In this work, the cytotoxic effect of a composite of Al 2 O 3 and CNTs functionalized with 3-aminopropyl-triethoxysilane (APTS; APTS, 125-5000 μg /mL) was evaluated in Vero cells. Cell viability was determined by MTT assay and Hoechst staining, 72 h after treatment. Additionally, the hemolytic capacity of the nanomaterial was evaluated in human red blood cells. The lowest cytotoxicity values were attained at 1.5 % CNTs by MTT. and 1.0 % by Hoechst staining. Nanometric Al 2 O 3 -CNT showed the highest cytotoxicity as compared with the micrometric composite. The APTS-functionalized composite was cytotoxic starting at 500 μg/mL and higher concentrations, with less than 50 % cell viability attained at 5000 μg/mL. Cells treated with Al 2 O 3 -functionalized CNTs showed significantly lower viability as compared to those treated with Al 2 O 3 -functionalized CNTs at concentrations above 500 μg/mL (p < 0.05). Overall, the Al 2 O 3 -CNTs nanocomposite did not significantly affect Vero cells viability at lower concentrations (below 1000 μg/mL). Moreover, none of the treatments showed hemolytic activity, implying that the higher cytotoxic effect was associated to the nanometric scale of Al 2 O 3 -CNTs composite, CNTs percentage and APTS functionalization, but not affecting directly the integrity of the red blood cells membrane. So far, this is the first in vitro approach on the evaluation of Al 2 O 3 with CNTs material and APTS functionalization in Vero cells.