Characterization of water-soluble fullerene C60 nanoparticles using asymmetrical flow field-flow fractionation and atomic force microscopy

Fullerene C60 nanoparticles are considered for a variety of biological applications such as imaging probes, antioxidants and drug delivery. Size characterization of nanoparticles using methods such as light scattering often gives values in the order of tens or hundreds of nanometers. Interpretation of the results becomes even more complicated when the medium contains ions that result in aggregation of nanoparticles. In this study we used Asymmetrical flow field-flow fractionation (AsFlFFF) to determine the size distribution of soluble C60 (C60-OH) nanoparticles in aqueous solutions of different pH and ionic strength. A 100 times increase in the ionic strength, resulted in about 60% increase in the size of the nanoparticles. However changing the pH from 6 to 10 did not result in a significant difference in size. The obtained particle size was verified using Atomic force microscopy