Calcium molybdate nanoparticles formation in egg phosphatidyl choline based liposome caused by liposome fusion

In order to achieve the highly efficient ^99mTc production from ¹⁰⁰MoO₃ by the ¹⁰⁰Mo(n, 2n)⁹⁹Mo reaction, we have developed a new protocol to synthesize nano-sized Mo particles, of which the size was controlled by the inner space of the liposomes. Calcium and molybdate ions were encapsulated into ∼100 nm size liposomes. The liposome suspensions were then mixed and heated to promote the membrane fusion. As a result, the insoluble CaMoO₄ nanoparticles precipitated inside the liposomes. The median particle diameter of 168 nm and average diameter of 169 ± 56 nm (n = 109) were obtained from an SEM image, and the particles have a powellite-structure. The formation process of the particles was then examined. The formation of nano-sized CaMoO₄ was observed by the high resolution TEM image and TEM image of negative-stained liposome. At the room temperature, the fusion of liposome did not occur significantly. These results suggest that nanocrystals of the CaMoO₄ were likely formed in the liposomes because of the liposome fusion and aggregated during the drying processes of reaction solution.