The Study and Comparison of the Uptaking and Intracellular Trafficking of Lipoplex Nanoparticles and Polyplex Nanoparticles by Quantum Dots-FRET

Fluorescence resonance energy transfer (FRET) is a useful tool in evaluating molecular dynamics at the nanometer scale. Quantum dots (QDs) are good donors for FRET because of their unique photo physical properties such as broad absorption, narrow emission spectra, and high photostability which overcome the disadvantages in conventional FRET, such as spectral crosstalk, photo bleach and direct acceptor excitation.

In our work, QD605-Amine or QD605-polycations and Cy5-oligonucelotides (Cy5-G3139 and Cy5-G2040) were chosen as the FRET pair. They were either encapsulated in lipoplex nanoparticles or form polyplex nanoparticles by the electrostatic interaction. The size, charge and structure of lipoplex nanoparticles and polyplex nanoparticles were characterized by dynamic light scattering, zeta potential analyzer and Cryo-TEM. The biological activities of lipoplex nanoparticles and polyplex nanoparticles were examined in KB cells. Flow cytometry and confocal microscopy were used to investigate the uptaking and the following intracellular fate of the nanoparticles in KB cells at 0, 24 and 48hr post transfection. The antisense activitives against Bcl-2 and R2 were evaluated using real time PCR and western blot.

Results have shown that QDs do not affect the structure and biological activity of the lipoplex nanoparticles and polyplex nanoparticles. We have demonstrated that QD-FRET is a sensitive way to study the uptaking and the intracellular trafficking of lipoplex nanoparticles and polyplex nanoparticles