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Diffusion Controlled Synthesis of Plasmonic Nanoparticles for Highly Sensitive Detection and Imaging

초록/요약

Colloidal plasmonic nanoparticles have been widely used in various applications ranging from biomedicine to catalysis, owing to their unique physiochemical properties. Among them, hyper-branched plasmonic nanoparticles two-dimensional (2D) structure are promising candidate for highly sensitive detection in biomedical applications, because it provide a high surface area that is available for molecules to access without diffusion limitation, far-field response at different wavelengths from visible to near-infrared region, and strong near-field enhancement. However, synthesis of these colloidal particles proceeds under kinetically controlled conditions (i.e., diffusion controlled growth conditions) induced by complicated synthetic methods having a long time with multiple steps, a delicate temperature control, and additional shape-directing molecules such as surfactants, which often suffer from low selectivity, yield, and production amount. Therefore, a novel method that provide a diffusion controlled growth condition without shape-directing molecules at room temperature is highly desirable. On the other hand, in vivo applications of plasmonic nanoparticles such as cellular imaging are often limited by weak colloidal stability and low endocytosis. To overcome these limitations, various kinds of materials such as lipids, polymers, and DNA have been used to functionalize the surface of plasmonic nanoparticles to form a hybrid structure. Among these materials, liposomes have attracted much attention for the development of hybrid structures with nanoparticles since they maintain colloidal stability as well as intracellular delivery efficiency. However, conventional methods for synthesis of hybrid nanoparticles have limitations in yield, selectivity, and structural uniformity for the desired nanoparticles. Hence, a new method is desirable to provide uniform, high yield and selectivity. Here I propose a diffusion controlled synthetic method that allow a formation of 2D hyper-branched plasmonic nanoparticles and liposome/plasmonic hybrid nanoparticles in solutions by controlling a molecular diffusion of metal precursor and reducing agent at various liquid interface (i.e., oleic acid/water interface and lipid bilayer/water interface. The 2D hyper-branched plasmonic nanoparticles are selectively synthesized under diffusion-controlled growth conditions at 2D oleic acid/water interface. The liposome/plasmonic hybrid nanoparticles are successfully formed with high yield and selectivity by designing liposome encoded with reducing agent and exploiting a diffusion of metal precursor into the liposome.

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