N-acetyl-l-cysteine protected cadmium telluride quantum dots with a diameter of 3–5nm were synthesized in aqueous solution. The interaction between N-acetyl-l-cysteine/cadmium telluride quantum dots and doxorubicin was investigated by ultraviolet–visible absorption and fluorescence spectroscopy at physiological conditions (pH 7.2, 37°C). The results indicate that electron transfer has occurred between N-acetyl-l-cysteine/cadmium telluride quantum dots and doxorubicin under light illumination. The quantum dots react readily with doxorubicin to form a N-acetyl-l-cysteine/cadmium telluride-quantum dots/doxorubicin complex via electrostatic attraction between the NH 3 + moiety of doxorubicin and the COO − moiety of N-acetyl-l-cysteine/cadmium telluride quantum dots. The interaction of N-acetyl-l-cysteine/cadmium telluride-quantum dots/doxorubicin complex with bovine serum albumin was studied as well, showing that the complex might induce the conformation change of bovine serum due to changes in microenvironment of bovine serum.