Nanocrystals @ Liposomes: The formation and characterization of quantum dot and aniosotropic gold nanoparticle encapsulated liposomes

Emren Nalbant-Esenturk and A. R. Hight Walker

Optical Technology Division, Physics Laboratory

The liposomes studied here are nanosized, unilamellar vesicles which consist of amphiphilic lipids, enclosing an aqueous core. The lipids are predominantly phospholipids that form bilayers similar to those found in biomembranes. Nanocrystal encapsulated liposomes or “nanovials” have been attracting great interest due to their extensive applications in biochemical and biomedical areas such as drug targeting and delivery, and tumor imaging and diagnostics. Our experiments focus on the encapsulation of quantum dots; specifically cadmium selenide nanocrystal compounds with a zinc sulfide shell, inside the core of the liposomes. Transmission Electron Microscopy (TEM) studies confirmed the encapsulation of quantum-dots by liposomes. The quantum-dot @ liposome complexes have been observed by Total Internal Reflection Fluorescence Spectroscopy (TIRFS) and demonstrate an unexpected Fluorescence Resonance Energy Transfer (FRET) between the internal quantum dots and dyes implanted in the liposome membrane. The measured photoluminescence (PL) is neither shifted nor quenched when the nanocrystals are encircled by the lipid bilayer. Another aspect of the study is optimizing the synthesis and structure of non-spherical gold nanoparticles and encapsulating them in the liposomes. These metallic nanoparticles with aniosotropic shapes provide enhanced optical properties, which lend them to good candidates for spectroscopic techniques such as Surface Enhanced Raman Spectroscopy (SERS). Star-shaped gold nanoparticles have been prepared and characterized via UV-Vis spectroscopy and TEM.

Author Information:

Name: Emren Nalbant-Esenturk

Mentor's name: Angela R. Hight Walker

Division: Optical Technology, 844

Laboratory: Physics

Building/Room: 216/B225

Mail Stop: 8443

Telephone #: 301-975-8241

Fax #: 301-975-6991

Email: emren.nalbant-esenturk@nist.gov

Sigma Xi: not a member

Category: Physics