Carbon nanotube-based stimuli-responsive nanocarriers for drug delivery

In cancer therapy, smart nanocarriers are one of the most important nanoscale vectors of therapeutic agents. In this study, magnetic carbon nanotubes are functionalized with stimuli-responsive polymeric shells, which have thermal sensitivity and redox sensitivity due to the presence of PNIPAM-co-PHEMA and disulfide bonds, respectively. The chemical-physical properties of the nanovectors have been specified and used in a pinpointed DOX delivery system. At 25 degrees C, 12% of DOX was released from poly(NIPAM-HEMA-SS)/MN-MWCNTs in 12 h; as the temperature increased to 41 degrees C, the cumulative release amount of DOX in 12 h increased to 41%. Moreover, it was shown that in the presence of DTT, a more rapid release rate of DOX was observed. The in vitro hemolysis and in vivo biochemical analysis results revealed negligible toxicity of poly(NIPAM-HEMA-SS)/MN-MWCNTs in mice at a high dosage in the course of a 10 day experiment. The temperature responsive cytotoxicity of DOX-poly(NIPAM-HEMA-SS)/MN-MWCNTs was determined in vitro. In addition, with increasing temperature, the viability significantly decreased; the cell survival ratio was reduced from 59% +/- 1% at 37 degrees C to 50% +/- 2% at 41 degrees C at a concentration of 2 mu g mL(-1) because of the increased drug release under these conditions, likely as it was observed during in vitro drug release.