Understanding the biological and ecological implications of safe nanotechnology

Our recent paper, "Dendrimer-fullerenol soft-condensed nanoassembly" published in The Journal of Physical Chemistry C, showed how the soft nanomaterial dendrimer can be used to remediate the environment from potentially toxic nanomaterials. Here, we used fullerenol -- a 60 carbon molecule in the shape of a buckyball and functionalized with hydroxyl groups -- as a model system. Such an assembly also has implications for drug delivery.

We found that the assemblies of dendrimers and fullerenols were strong, spontaneous, and thermodynamically favorable at neutral water pH and ambient temperature and pressure.

Dendrimers are highly branched, polymeric macromolecules with a high degree of surface functionalities. Their branching determines their generation number (G) -- the higher the generation, the greater the degree of surface functionalities. We used both G1 and G4 poly(amidoamine) (PAMAM) dendrimers and found that both these dendrimers hosted one fullerenol per primary amine on the dendrimer surfaces. However, G4 PAMAM dendrimers hosted fullerenols 40 times better than G1, simply because of their higher degree of surface functionalities. Based on our findings, we recommended proper loading capacities of fullerenols for G1 and G4 dendrimers in drug delivery and environmental remediation.

With the advent of new technologies, the public often becomes skeptical of their implications on the environment. In our group, we strive to understand the biological and ecological implications of safe nanotechnology. This article was a part of that effort. Fullerenols have shown great potential in nanomedicine as well as in electronics. Dendrimers of generations five and below have been proven biocompatible, and have been used as MRI contrast agents and drug delivery vehicles. In this paper we provided a proof-of-concept on the use of a benign dendritic technology as a robust drug delivery vehicle and a solution to environmental remediation of discharged nanomaterials.

Our group, led by my advisor Dr. Pu-Chun Ke and funded by the National Science Foundation, has delved into a crucial topic of frontier research termed "nanoparticle-protein corona". In short, nanoparticles do not interact directly with living systems but are often coated with biological fluids in the form of a protein corona. Another direction in our group, through collaboration between Dr. Ke and Dr. David Ladner in Clemson's Department of Environmental Engineering and Earth Sciences and funded by the U.S. Environmental Protection Agency is to employ dendritic polymers for remediating oil spills.

Priyanka Bhattacharya is a PhD student at Clemson University's College of Engineering and Science.