Formation of Photosensitizing Crystalline C sub(60) Particles by Ink-Jet Method

The crystalline fullerene C60 particles were formed and immobilized on poly(dimethylsiloxane) (PDMS) substrates under the various discharge conditions by an ink-jet method, and investigated for the reactive oxygen species (ROS) generation property under visible light irradiation. The particles were synthesized by discharging a toluene solution dissolved C60 and poly(methyl methacrylate) (PMMA) with the ink-jet spotting system. The ROS generation was evaluated by comparisons of the fluorescence intensities measured for the formed particles under green laser irradiation and in a dark room using fluorescent dyes, 2',7'-dichlorofluorescein diacetate and dihydroethidium. The results of transmission electron microscope (TEM) observation showed that the formed particles consisted of crystalline C60. The optimal ink-jet discharge conditions for synthesizing the particles to generate more ROS were found. In the case of the optimal conditions, the structure in which the needle-like particles were three-dimensionally formed was confirmed. The surface area of the crystalline C60 particles was calculated using the SEM observation results, and it was suggested that when the needle-like finer particles were three-dimensionally formed under the optimal conditions, increasing the surface area lead to an increase in the ROS generation amount.