Stable aqueous fullerene colloidal suspensions (nC(60)) are demonstrated to rely on the [6,6]-closed epoxide derivative of the fullerene (C(60)O) for stability. This derivative is present, though often unrecognized, in small quantities in nearly all C(60) starting materials due to a reaction with air. The low-yield formation of nC(60) from organic solvent solutions results from a preferential partitioning and thus enrichment of C(60)O in the colloidal particles. This partitioning is significantly retarded in the nC(60) synthesis method that does not involve organic solvent solutions: long-term stirring in water. Instead, this method relies on trace levels of ozone in the ambient atmosphere to produce sufficient C(60)O at the surfaces of the nC(60) particles to allow stable suspension in water. Controlled-atmosphere syntheses, deliberate C(60)O enrichment, light scattering measurements, and extraction followed by HPLC analysis and UV-visible absorption spectroscopy support the above model of nC(60) formation and stabilization.

ENPs can be efficiently attached to the RBCs without adversely affecting cellular function, and this may potentially enhance circulatory half-life of drug molecules.

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A modular approach for the synthesis of polymer networks with well-defined node and cross-linking dimensions is described. Each node or tie point in the network is a cyclodextrin molecule, which imparts discrete molecular guest–host capabilities to the network. C60 fullerenes homogeneously intercalate in the network, presumably via van der Waals guest–host interactions with the hydrophobic γ-cyclodextrin cavity, resulting in stable C60-filled polymer networks with improved mechanical properties. Networks prepared with α-cyclodextrin, whose inner cavity is smaller than γ-cyclodextrin, and smaller than the C60 diameter, do not yield materials with stable C60 intercalation. Characterization of the final composites reveals that the cross-linked γ-cyclodextrin-based composites maintain stable C60 concentrations, even after multiple extractions with toluene, which itself is a good solvent for C60. Membranes prepared from the cyclodextrin polymer network, prior to C60 intercalation, should also be useful for C60 extraction from C60–solvent mixtures. The synthetic route we describe here is not limited to C60 and should be generally applicable to a wide variety of guests.

The aim of the present study was to evaluate a library of poly-L-lysine (PLL)-graft (g)-polyethylene glycol (PEG) copolymers for the ability to encapsulate effectively a model protein, bovine serum albumin (BSA), and to characterize the stability and protein function of the resulting nanoparticle. A library of nine grafted copolymers was produced by varying PLL molecular weight and PEG grafting ratio. Electrostatic self-assembly of the protein and the grafted copolymer drove encapsulation. The formation of protein/polymer nanoparticles with a core/shell structure was confirmed using PAGE, dynamic light scattering, and electron microscopy. Encapsulation of the BSA into nanoparticles was strongly dependent on the copolymer-to-protein mass ratio, PEG grafting ratio, and PLL molecular weight. A copolymer-to-protein mass ratio of 7:1 and higher was generally required for high levels of encapsulation, and under these conditions, no loss of protein activity was observed. Copolymer characteristics also influenced nanoparticle resistance to polyanions and protease degradation. The results indicate that a copolymer of 15-30 kDa PLL, with a PEG grafting ratio of 10:1, is most promising for protein delivery.