Fullerenes, allotropic forms of carbon, have very interesting pharmacological effects and
engineering applications. However, a very low solubility both in organic solvents and water
hinders their use. Fullerene C60, the most studied among fullerenes, can be dissolved in water
only in the form of nanoparticles of variable dimensions and limited stability. Here the effect on
the production of C60 nanoparticles by a native and denatured hen egg white lysozyme, a highly
basic protein, has been systematically studied. In order to obtain a denatured, yet soluble,
lysozyme derivative, the four disulfides of the native protein were reduced and exposed cysteines
were alkylated by 3-bromopropylamine, thus introducing eight additional positive charges. The
C60 solubilizing properties of the modified denatured lysozyme proved to be superior to those of
the native protein, allowing the preparation of biocompatible highly homogeneous and stable
C60 nanoparticles using lower amounts of protein, as demonstrated by dynamic light scattering,
transmission electron microscopy and atomic force microscopy studies. This lysozyme
derivative could represent an effective tool for the solubilization of other carbon allotropes
