With proper functionalization of their surface, CNTs can selectively attach to specific cancer cells rather than to surrounding normal/healthy cells. Under NIR photoluminescence ranging from 700 to 1100 nm, CNTs can effectively absorb NIR energy and subsequently transfer it to thermal energy. This increases the cancer cell temperature to the lethal temperature (50–70°C). Experimental studies using various CNTs as the cancer hyperthermia agent with NIR have been reported. However, the mechanism of heat transfer in these cancer hyperthermia systems have not been understood quantitatively.

Mesoscopic modelling

A multidisciplinary team, from the Carbon-based Nanoengineering Materials Lab, National University of Singapore and the Computational Transport Processes Group, University of Oklahoma, comprehensively investigate the heat transfer mechanism in a cancer hyperthermia system using an off-lattice Monte Carlo approach. A mesoscopic model is built with the normal tissue, the cancer cell and the CNTs distributed randomly on a cancer cell surface.

Heat transfer

By quantizing the thermal energy released from CNTs, the temperature increase rates of the cancer cell and the surrounding tissue can be determined. The effects of interfacial thermal resistances between multiphases, CNT morphologies and CNT orientations (perpendicular, random and parallel to the laser beam) on the temperature increasing rates of the normal tissue and the cancer cell are also quantified.

Importance of orientation and functionalization

The research finds that a high energy absorbance efficiency of CNTs can be achieved by utilizing smaller diameter CNTs with perpendicular orientation to the laser beam. Higher local temperature of the cancer cell compared with the surrounding normal tissue can be achieved by using CNTs with appropriate functionalization around their surface.

More information about the research can be found in the journal Nanotechnology 25 205101.

Further reading

Nanographene oxide destroys tumours (Nov 2013)
Photothermal therapy eradicates tumours targeted by carbon nanotubes (Sept 2013)
Formulating dual-function nanoparticles for photodynamic and photothermal cancer therapy (Jan 2012)