Octanol-water partition coefficient (Kow) is a conventional measure of hydrophobicity of organic compounds, and has been recently applied to NPs. However, the larger size of NPs may undermine the fundamental assumptions of KOW application. We conducted the Kow measurement for different NPs: aqueous C60 (aqu-C60), tetrahydrofuran-C60, fullerol, nano-silver, and citrate-coated nano-gold (Au-Ci). Our results showed that larger Kow was obtained from NPs that exhibited greater hydrophobicity. We also showed that as size increased, KOW of aqu-C60 increased, but KOW of Au-Ci was not dependent on size. Dark field microscopy revealed that Au-Ci NPs ( 100 nm) were accumulated near the water-octanol interface. Overall, our study demonstrated that the partition of NPs is determined by both hydrophobicity and size. The current application of Kow as a measure of hydrophobicity for NPs is inherently flawed and further investigation is needed.

Octanol-water partition coefficient (K<sub>ow</sub>): Is it a good measure of hydrophobicity of nanoparticles?

244th National Meeting (2012)

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Octanol-water partition coefficient (Kow): Is it a good measure of hydrophobicity of nanoparticles?

Octanol-water partition coefficient (K_ow): Is it a good measure of hydrophobicity of nanoparticles?