Synthesis and Investigation of New Core-Shell Nanoparticles as Molecular Carrier Systems
Final Report Abstract
The objective of this joint proposal was to combine the expertise from both research groups on the synthesis of polyethylenes by chain walking polymerization by the Guan group (University of California, Irvine) and the grafting of polyglycerol by the Haag group (Freie Universität Berlin) to obtain amphiphilic core-shell nanoparticles for the transport of hydrophobic drugs or dyes in water. The understanding of the structure-property-relationship for the encapsulation in those kind of nanocarriers is important for the design of highly efficient molecular nanocarriers and may find application in drug delivery and ink formulation. In this project, a core-shell nanocarrier, having a dendritic polyethylene core and a hyperbranched polyglycerol shell, was successfully synthesized and thoroughly characterized with the help of NMR, static and dynamic light scattering and cryo-TEM. Two hydrophobic dyes, pyrene and Nile red, were encapsulated in water and their transport behavior was investigated by UV-Vis, fluorescence, dynamic light scattering and cryo-TEM. Both dyes are unambiguously encapsulated in a unimolecular fashion and it could be shown that pyrene is situated in the region of the hydrophobic core. In addition to that, we could show the advantages of unimolecular transport in the delivery of hydrophobic guests into living cells in dilute conditions. Thus, these core-shell unimolecular nanocarriers are promising candidates for the formulation and delivery of poorly water soluble active agents across cellular membranes. The modification of the hydrophobic core with biphenyl units was possible, though needs further optimization since the catalysts activity was strongly diminished. The study about nanodiamond as a core was also successful. Polyglycerol cotild be grafted from and to the hydroxyl-functionalized nanodiamond core. However, no encapsulation of hydrophobic guests could be observed, which leads to the important conclusion that the core topology of core-shell nanocarriers has to be rather flexible than hard. The investigation of the effect of different sizes of the core-shell nanocarriers on the encapsulation behavior is currently ongoing.
Publications
- Dissertation, University of California, Irvine, 2008. Structural and Chemical Modification of Late Transition Metal Polymerization Catalysts
C. S. Popeney
- ACS Macro Letters 2012, 7, 564-567. Tandem Coordination, Ring-Opening, Hyperbranched Polymerization for the Synthesis ofWater-Soluble Core-Shell Unimolecular Transporters
C. S. Popeney, M. C. Lukowiak, C. Böttcher, B. Schade, P. Welker, D. Mangoldt, G. Gunkel, Z. Guan and R. Haag
(See online at https://doi.org/10.1021/mz300083y)
