Stabilization of C60 nanoparticles by protein adsorption and its implications for toxicity studies

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Abstract:

Materials: C60 molecules (99.9 % purity) were purchased from Tokyo Kasei Kogyo. Methods: Simple and well described dispersion protocols. DLS measurement to assess the hydrodynamic diameter.

C60 nanoparticles coagulate over time in PBS. Adding 1mg/ml – or more – HSA prevents this coagulation. Albumin stabilized C60 nanoparticles have a larger hydrodynamic diameter, compared to albumin free C60 nanoparticles, this diameter is only slightly dependent on the HSA concentration.

This paper studies the effect of serum albumin on the dispersion of C60 nanoparticles in phosphate buffered saline. Relative low concentrations of C60 nanoparticles (9.3 × 10-6 M) are stable in a buffer enriched with 1 mg/ml albumin. The finding is certainly interesting because it allows the study of “monodisperse” nanoparticles in e.g cell cultures, but it also introduces a layer on the material, changing the biological interactions – depending on the objectives of the study this can be an advantage or an disadvantage.

Notes:

The stability of a dispersion can be considered as an important parameter in health effect studies. In this study the dispersion stability of nanoparticles of C60 under condition simulating the physiological environment was examined. Adding proteins (1 mg/ml or higher) to a phosphate buffered saline (PBS) solution resulted in a stable dispersion of C60 nanoparticles. Dynamic light scattering (DLS) measurements showed that the human serum albumin (HSA) adsorbs onto the surfaces of the C60 nanoparticles, forming an expanded layer which prevents salt-induced coagulation.

Although this work only shows stabilisation of one type of nanomaterial (C60), at a relative low concentration (9.3 × 10-6 M), it has the merit to test, in a relative simple way, the potential of a nanomaterial to be present as a mono-disperse particle in a biological fluid. This observation can possibly have a serious impact for all health and/or therapeutic related studies using nanomaterials.