Journal: ACS Nano
Authors: Sarah P. Sherlock, Scott M. Tabakman, Liming Xie, and Hongjie Dai
Affiliation: Stanford University, Department of Chemistry
Nanomaterials have a wide variety of uses and we have just begun to discover their capabilities. They have shown great potential in medical applications including the treatment of cancer. The ability of an anti-cancer drug to target specific areas of the body and to monitor that drug’s progress is extremely useful to the medical community. This paper discusses the synthesis of a nanomaterial with these properties.
Previous work with the anti-cancer drug doxorubicin (DOX) led to the synthesis of polymer spheres loaded with DOX and covered with gold half shells. These particles released DOX upon radiation (enabling targeting of cancer cells), but were over 70 nm in size. This is large for biological use and they also lacked the ability to be monitored. By adding a magnetic layer, the particles could be monitored, but they were now approximately 100 nm.
In this article the authors describe the synthesis of a “highly integrated nanoparticle system uniquely capable of drug delivery, imaging, and photothermal therapy.” The authors loaded DOX on to an iron-cobalt core surrounded by a graphite shell (FeCo/GC). This FeCo core is highly magnetic and small (approximately 4 nm). The magnetic properties were hypothesized to allow for monitoring using MRI and in fact the authors were able to monitor cellular uptake of FeCo/GC-DOX using MRI. These results were confirmed using fluorescence.
The researchers tested the toxicity of the material on breast cancer cells. Both FeCo/GC-DOX and free DOX led to cell death; however at lower concentrations free DOX was more effective. This was attributed to the slow release of DOX from the FeCo/GC-DOX conjugate. Cells exposed to just FeCo/GC showed no significant cell death indicating that DOX was responsible for the cell death.
Hyperthermia, heat treatment, has been known to increase the efficacy of some anti-cancer drugs. Graphite materials are known to generate heat after exposure to near infrared radiation. Exposure of cells to FeCo/GC-DOX and FeCo/GC followed by irradiation with 808 nm light led to photothermal heating of the cells. A control condition and cells exposed to free-DOX did not exhibit heating during radiation. After irradiation the cells were washed to remove any DOX. The cells were then allowed to grow for two days. FeCo/GC-DOX was found to be two times more effective at inhibiting cell growth following radiation while irradiation had little influence on the inhibition of cell growth in any other condition.
The authors were able to synthesize a nanomaterial that is effective in inhibiting cancer cell growth, can be imaged using MRI, and can have increased toxicity in specific areas using near IR irradiation. These concerns will continue to be an active area of research as cancer is a complex and widespread issue.