Synthesis and evaluation of apoptosis induction levels of carbamate- and thiocarbamate-functionalized multi-walled carbon nanotubes

Abstract

Functionalized carbon nanotubes (CNTs) have been widely employed for biomedical applications including delivery of gene, peptide and drug, imaging and biosensor design. Carbon nanotubes are well known for their fascinating properties and promising potential for versatile biological applications. Considering the importance of functionalization to improve CNTs solubility, we designed a procedure to decorate multi-walled carbon nanotubes surface with carbamate and thiocarbamate groups, since these functional groups are common in natural products with antiproliferative effects on cancer cells. To produce carbamate and thiocarbamate functional groups, the nanotubes were first hydroxylated and then reacted with different isocyanate/isothiocyanate derivatives in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to give multi-walled nanotubes functionalized with carbamate/thiocarbamate functional groups. The apoptotic activity of these synthesized nanotubes was tested on neuroblastoma N2A cell line. A significant increase in the number of apoptotic cells was observed in N2A cell treated by carbamate/thiocarbamate-functionalized multi-walled nanotubes. The apoptosis level increased as the concentration of compound increased up to 0.1 µg/ml. t-But-carbamate–MWNT and 3-Br-Ph-thiocarbamate–MWNT (50 ng/ml) showed the highest apoptosis level with 1.8- and 1.7-fold increase compared to doxorubicin.