Polymerization of Nanocrystal Quantum Dot–Tubulin Bioconjugates

Nanocrystal quantum dot (NQD)-tubulin bioconjugates were prepared using a two-step crosslinking procedure. NQD-decorated microtubules were successfully polymerized directly from the NQD-tubulin conjugates to form nonaggregated, full-length (several micrometers) biopolymers. However, polymerization kinetics were slowed in comparison with unmodified tubulin and tubulin modified with small-molecule dyes or biotin. Association with the relatively large nanocrystals, therefore, interferes to some extent with tubulin´s ability to polymerize. These results suggest that before NQDs are used extensively as fluorescent labels in studies of biomolecular activity, the impact of NQD bioconjugation must be well understood