A biotinylated paclitaxel derivative with an extra-long-chain (LC-LC-Biotin) spacer arm was synthesized using an improved synthetic reaction sequence. The biotinylated paclitaxel analogue retained excellent microtubule stabilizing activity in vitro. Furthermore, it was shown that this analogue can simultaneously engage streptavidin and the binding site on microtubules, making it suitable for localization studies or for the attachment of paclitaxel to solid substrates via a streptavidin linkage.