Water Structured by Very Low Concentrations of Fullerol: Implications for Dominant Role of Water in Their Antioxidant and Radioprotective Effects

Abstract

Fullerene compounds are known to possess antioxidant properties, a common property of chemical radioprotectors. It is recently hypothesized that the antiradical action of hydrated fullerenes in water medium is due to a hydrated free radical recombination catalyzed by specific water structures, and not a result of direct binding to double bonds of fullerene core. This hypothesis was only logical explanation for the peculiar results of OH-removing efficacy in reverse correlation with fullerene concentration. [1] The proposed model of antiradical activity corresponds with the model of exclusion zone water formed next to charged surfaces or so called liquid crystalline water. [2] Fullerols – water-soluble fullerene derivate, being hydrophilic and highly electronegative have basic properties of surfaces for exclusion zone water formation. However, exclusion zone water spectral features are not yet defined for nanostructures because appropriate methods are lacking. To determine whether fullerol creates exclusion zone water, a newly developed framework for analysis of water near infrared spectra in the region of 1st overtone of water called Aquaphotomics [3], was applied. Using the aqueous fullerol solutions serially diluted in concentrations ranging from 1.128mg/ml to 15.625ng/ml it was found that near infrared spectra of aqueous solutions with ultra-low concentrations of fullerol had the same spectral features observed in near infrared spectra of water next to Nafion – a known and potent exclusion zone creator. These common spectral features for exclusion zone water and highly diluted fullerol solutions correspond to strong hydrogen-bonded large water molecular structures (region from 1447 to 1518 nm). These findings confirm the hypothesis of exclusion zone formation around fullerols in aqueous media and suggest dominant role of water in their antioxidant activity.