Micellar encapsulation of nanoparticles using PEG-phospholipid is an efficient approach in converting hydrophobic nanoparticles to hydrophilic/biocompatible ones. For both magnetic nanoparticles (MNPs) and quantum dots (QDs), there are interests to fabricate cluster-nanoparticle micelles (CNMs) and/or single-nanoparticle micelles (SNMs). CNMs have a relative large hydrophobic core and get a flexibility to load drugs in the cores, while keeping magnetic moments or fluorescence for magnetic resonance imaging (MRI) or optical imaging. CNMs adopting MNPs also enhance magnetic relaxivity of micelles for MRI. SNMs would have smaller sizes compared to CNMs, which will benefit their cell/tissue uptake and thus enhance their bioavailability. Currently, the chloroform-based dry film method is the widely reported approach for the preparation of CNMs or SNMs. However, this method usually takes a long time to air-dry chloroform. Moreover, it involves heating or hot water for the film hydration,which may be incompatible with certain functional groups on the PEG end (e.g., maleimide). Recently, a dual solvent exchange method has been reported adopting both chloroform and DMSO. However, it is developed for SNM preparation and also involves additional solvent DMSO to increase cost and more experimental steps such as DMSO removal. There is lack of a simple and efficient method that can be adapted to fabricate either CNMs or SNMs. In this work, a capable method was developed for the fabrication of CNMs or SNMs. Briefly, a mixture of nanoparticles and PEG-phospholipid in THF is added into H2O under ultrasonication. By simply adjusting the mass ratio of nanoparticles to PEG-phospholipid, the sonication power and the mixture addition strategy, CNMs or SNMs of MNPs and QDs can be produced without slow air-dry, heating, or additional solvents. The produced CNMs or SNMs were characterized in terms of their sizes, optical properties, colloidal stability, and/or magnetic relaxivity (by MRI).

Generic approach to fabricate cluster-nanoparticle or single-nanoparticle based characterization

248th National Meeting (2014)

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