Аннотация:Aqueous fullerene solutions (dispersions) are very promising materials in biomedicine and biotechnology. Of importance are the traceability of their production and the characterization of their optical and colloidal properties. Thermal-lens spectrometry as a method suitable for both optical and thermophysical studies was used to elucidate the forms of non-modified fullerene existence in their aqueous dispersions and to determine low concentrations of fullerenes C60 and C70 in various media. It was shown that the residual amounts of toluene in aqueous fullerene dispersions made according to the solvent-exchange protocol could be detected by thermal lensing. As a result, the technique for aqueous fullerene dispersion production was improved providing higher fullerene concentrations. The limits of detection of fullerenes C60 and C70 are ca. 100 ng/mL, which are 20-fold lower than for conventional spectrophotometry. The distinction between aqueous fullerene dispersions in comparison with organic solutions of fullerenes caused by the formation of large clusters are shown by the comparison of transient and steady-state calibration curves for aqueous and organic fullerene solutions and model reference systems under various thermal-lens excitation conditions. The advantages of thermal lensing for such colloidal systems are discussed.