In the past few years the advance of nanotechnology has seen the emergence of composite nanoparticles, i.e. composite structures incorporating two or more nanoparticles to offer multi-functionality or entirely new properties. Here we describe our efforts to develop a class of composite nanoparticles, namely magnetic quantum dots (MagDot), which combines the magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) and the fluorescent properties of quantum dots (QDs). Three different synthesis strategies, including crosslinking, crystallization and self-assembly, were systematically investigated. The strategy based on micelle-templated self-assembly was selected due to bright fluorescence and excellent photostability of resulting nanostructures. We have shown synthesis of micelle templated multifunctional particles by direct coencpasulation of QDs and SPIONs in block copolymer micelles and also by a 2 step hierarchical process where micelle encapsulating nanoparticles with single functionality are synthesized, followed by their further self assembly into multifunctional composites using protein-protein or complimentary DNA interactions. We have also shown large scale synthesis of self assembled structures by combining the interfacial instability method with electrospray. MagDots formed using these approaches were further combined with two other emerging technologies, namely magnetic field engineering and molecular motor-enabled control to achieve sub-femto molar detection, and manipulation of biomarkers including proteins, DNAs, and biological cells.

Magnetic quantum dots for simultaneous detection, manipulation, and tracking at nanoscale

245th National Meeting (2013)

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