Synthesis and Self-assembly of [60]Fullerene Containing Sulfobetaine Polymer in Aqueous Solution

Abstract

A series of well-defined stimuli responsive water soluble [60]fullerene (C₆₀) containing polymers such as polyelectrolytes (polyacids and polybases), polyampholyte and polyzwitterionic polymers were synthesized using atom transfer radical polymerization. The aqueous solution properties of these polymers with respective external stimuli such as pH, temperature and salt were studied using potentiometric and conductivity titration, light transmittance, laser light scattering and transmission electron microscopic techniques. The influence of polymer concentration, temperature, pH and electrolyte on the hydrodynamic radius (Rh), radius of gyration (Rg) and aggregation number (Nagg) of the particles were investigated in detail to elucidate the morphology of the particles. The morphology of the aggregates was further confirmed by the TEM micrographs. The cytotoxicity of the pH responsive C₆₀ containing well-defined polymers (PAA-b-C₆₀, C₆₀-b-PAA-b-C₆₀ and PEO-b-PAA-b-C₆₀) was studied to confirm the suitability of these particles as potential drug delivery vehicles. The binding interaction between the anti-cancer drug (doxorubicin) and C₆₀ containing pH responsive polymers was studied using isothermal titration calorimetry, and the implication of the results will be discussed.