2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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TechConnect Summit
Clean Technology 2008

Liposome-Quantum Dot Hybrids as Multimodal Therapeutic & Imaging Agent Delivery Systems

W.T. Al-Jamal, K.T. Al-Jamal, K. Kostarelos
Nanomedicine Laboratory, UK

Keywords:
quantum dots, liposomes, tumor imaging

Abstract:
Quantum dots (QD) have been widely explored as fluorescent probe for long term and multiplexing imaging purposes in vitro and in vivo. However, QD low hydrophilicity is considered a major obstacle that impedes their use. In this work, we report the construction of Lipid-QD bilayer vesicles (L-QD) by incorporation organic CdSe/ZnS QD within zwitterionic and cationic lipid bilayers, self assembling into small unilamellar vesicles. These L-QD hybrids rendered QD compatible with the aqueous environment and fluorescently labelled the lipid bilayers. The incorporation of QD in the acyl environment of the lipid bilayer led to significant enhancement of their optical stability during storage and exposure to UV irradiation compared to QD alone in toluene. Moreover, structural characterization of L-QD hybrid bilayer vesicles using cryogenic electron microscopy revealed that the incorporation of QD is taking place by hydrophobic self-association in ‘pockets’ within the biomembranes. The L-QD vesicles bound and were internalized in human epithelial lung cells (A549), and confocal laser scanning microscopy studies indicated that the L-QD were able to traffick intracellularly. cationic L-QD vesicles injected intratumorally, led to enhanced retention within human cervical carcinoma (C33a) xenografts. Furthermore, these novel L-QD hybrids showed high stability in vivo and different biodistribution profiles have been observed depending on the lipid bilyer characteristics. Rapid lung accumulation was achieved using cationic L-QD hybrids, while incorporation of PEG polymer into zwitterionic L-QD vesicles dramatically prolonged their blood circulation after systemic administration. The hybrid L-QD bilayer vesicles presented here are thought to constitute a novel delivery system that offers the potential for transport of combinatory therapeutic and diagnostic modalities to cancer cells in vitro and in vivo.


Nanotech 2008 Conference Program Abstract