Water-soluble quantum dots (QDs) are effective reagents,have minimal toxicity,are compatible with biological system,and have shown potential as tumor diagnostic agents.However,little is known about their biological behaviors in vivo.Our recent in vivo studies concentrated on the biokinetics of cadmium telluride (CdTe) QDs.Male ICR mice were intravenously given a single dose (2.5 μmol/kg body weight) of water-soluble cadmium-telluride (CdTe) QDs (the QDs are approximately 4 nm in diameter and have maximal emission at 630 nm).Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the kinetic action of 111Cd and 125Te for 7 days.The plasma kinetics of cadmium (Cd) and tellurium (Te) followed a two-compartment model,in which Te exhibited lower volume of distribution (107.41 ± 9.75 ml/kg vs.127.25 ± 5.65 ml/kg),AUC (15.28 ± 0.89 μg/ml?h vs.18.73 ± 2.29μg/ml?h),rapid elimination half-life (21.55 ± 0.24 h vs.49.28 ± 2.79 h),and clearance (10.38 ± 0.80 ml?kg-1?h-1 vs.14.81 ± 1.90 ml/kg?h),and a slower distribution half-life (7.17 ± 0.06 h vs.6.01 ± 0.58 h) compared to the Cd.Contrary to its relatively transient fate in the plasma,high levels of Cd persisted in the liver and kidneys throughout the experimental period.In the kidneys,the tissue concentration showed an increase after 72h.Compared with Cd,the overall half-life of Te in the body was very short.Moreover,Te accumulated primarily in the spleen,followed by liver and lung.The different plasma kinetics and distribution patterns of Cd and Te imply that CdTe QDs have been part of the degradation or aggregation in vivo.