Functionalisation of carbon nanotubes by methotrexate and study of synchronous photothermal effect of carbon nanotube and anticancer drug on cancer cell death.

Carboxylated functionalised multi-walled carbon nanotubes (f-MWCNT) were synthesised. Furthermore, folic acid (FA) and methotrexate (MTX) through ethylenediamine (ED) were attached to the surface of f-MWCNT to synthesise MWCNT-ED-FA and MWCNT-ED-MTX. Release studies of MTX as free drug and in MWCNT-ED-MTX were performed. These studies showed that MTX release rate from MWCNT-ED-MTX decreased in comparison with free MTX, which is due to the MTX attachment on the MWCNT. The anticancer effect of MWCNT-ED-FA and MWCNT-ED-MTX on the breast cancer cell line (MCF-7) was studied. Studies have shown that MWCNT-ED-MTX cytotoxicity is more than that of MWCNT-ED-FA, which is due to the presence of MTX. Furthermore, the anticancer effects of MWCNT-ED-FA and MWCNT-ED-MTX in the presence of infrared laser radiation on the MCF7 cell were studied. The experiments showed that in the presence of the laser, the cytotoxicities of MWCNT-ED-FA and MWCNT-ED-MTX were the same and increased in comparison with laser absence, which indicates that the photothermal effect is stronger than other factors and mask their effects. This effect can be related to laser radiation absorption by MWCNT and its conversion to heat which can induce cancer cell death. Targeting studies have shown that MWCNT-ED-FA is targeted to the cancer cells due to the presence of FA.