Quantum dot-labeled trichosanthin

Semiconductor quantum dots have been used for the first time to label trichosanthin. The absorption and fluorescent spectra of quantum dot-labeled trichosanthin were different from those of trichosanthin, but no changes were found in the enzymatic activity of quantum dot-labeled trichosanthin in comparison with trichosanthin. The distribution of quantum dot-labeled trichosanthin in the cytoplasm of a human choriocarcinoma cell is observed with two-photon laser scanning microscopy, and the aggregation of quantum dot-labeled trichosanthin in the cytoplasm is discussed.