Concern is growing about the potential impact of human exposure to carbonaceous nanomaterials (such as fullerenes) in the environment. A valid biological study of how native biomolecules interact with nanomaterials at the molecular level in physiological conditions requires the preservation of their physicochemical properties, yet most investigations rely on the use of modified fullerene conjugates or aggregates. We report the formation of a stable, water-soluble, well-defined complex between a single molecule of pristine C(60)-fullerene and a native protein, bovine serum albumin protein (BSA), with the normal three-dimensional structure of BSA preserved. The ability to produce a pristine C(60)-fullerene-BSA hybrid at a physiological pH range lays a solid foundation for studying carbonaceous materials, biodelivery systems, and transport mechanisms and for characterizing the potential effects of nanomaterials on wildlife and human health, both in vitro and in vivo.

Most current nanotoxicology research is focused on examining the influence of nanomaterials at the tissue and cellular levels. To explore these interactions on the molecular level, new carboxyfullerenes interact with transport proteins at the molecular level. The carboxyfullerenes exhibited an unusual mode of binding outside the calyx of beta-lactoglobulin (a typical representative of lipocalin family of barrier liquid proteins). The complexes were studied by various techniques, including mass spectrometry, UV/vis and circular dichroism spectroscopy, chromatographic methods, gel electrophoresis, and dynamic light scattering. The fullerene ligands were transferred from beta-lactoglobulin to human serum albumin (a representative of a blood transport protein), thus providing a model of how fullerene-based nanomaterials interact with biomolecules and are transported in biological systems.

The preparation and characterization of the stable equine skeletal muscle apomyoglobin and eee-isomer of tris-malonic acid [C60] fullerene complex is reported. For this new bio-nanomaterial preparation, a procedure of complexation-during-protein-refolding was used and the obtained compound sustained separation by gel-filtration and ion-exchange chromatography. The apomyoglobin-tris-malonic acid [C60] fullerene complex was characterized by UV-vis spectroscopy, steady state fluorescence, time-resolved fluorescence, and circular dichroism spectroscopies. Important information provided by this study, regarding the stability and properties of new material, may lead to a better understanding of the apomyoglobin protein binding characteristics, as well as to development of novel antioxidant and photodynamic therapeutic agents and components for bioelectronic devices.