Getting across the plasma membrane and beyond: Intracellular uses of colloidal semiconductor nanocrystals

Semiconductor nanocrystals (NCs) are increasingly being used as
photoluminescen markers in biological imaging. Their brightness,
large Stokes shift, and high photostability compared to organic
fluorophores permit the exploration of biological phenomena at the
single-molecule scale with superior temporal resolution and spatial
precision. NCs have predominantly been used as extracellular
markers for tagging and tracking membrane proteins. Successful
internalization and intracellular labelling with NCs have been
demonstrated for both fixed immunolabelled and live cells. However,
the precise localization and subcellular compartment labelled are
less clear. Generally, live cell studies are limited by the
requirement of fairly invasive protocols for loading NCs and the
relatively large size of NCs compared to the cellular machinery,
along with the subsequent sequestration of NCs in
endosomal/lysosomal compartments. For long- period observation the
potential cytotoxicity of cytoplasmically loaded NCs must be
evaluated. This review focuses on the challenges of intracellular
uses of NCs. Copyright (c) 2007 Camilla Luccardini et al. This is
an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution,
and reproduction in any medium, provided the original work is
properly cited.