Quantum dot nanocrystals are nanometer sized semiconductor particles, which can be
used for labeling biological systems. They are much brighter and more stable than
conventional fluorophores, making the system optimal for high resolution imaging and
long term studies. However, the potential for the use of quantum dots in the biological
sciences has yet to be realized due to the lack of reliable labeling methods using
commercially available reagents. Prior work in this area involves synthesizing and
chemically conjugating quantum dots to molecules of interest in-house which is both time
consuming and prone to human error. Additionally, non-specific binding and
nanoparticle aggregation currently prevent researchers from utilizing this system to its
fullest capacity.
We have developed labeling methods using commercially available quantum dots
specific to neurons and glia and have used these tools to label GFAP intermediate
filament cellular bridges. Since quantum dots are bright and provide detail into cellular
interactions, previously unidentifiable characteristics, such as GFAP bridges, are now
visible.
In addition, we have developed a technique to characterize the functional antibody bound
to conjugated QDots. We define functional antibody as the antibody available for
binding to the target ligands. We found that antibody oriented inwards on the Qdot is
unavailable for binding, due to steric reasons. Previous attempts to characterize quantum
dots never resulted in quantitative information which is necessary to determine the
concentration of quantum dots to be delivered to the system. Using standard gel
electrophoresis technology followed by membrane transfer, we have characterized the
amount of functional antibody bound to quantum dots from commercially available
conjugation kits.